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Reproductive allocation and cost play a crucial role in the survival of organisms, but research on these traits in bryophytes has been limited and inconsistent. To address this, we conducted a literature review focusing on bryophyte studies. Our goal was to clarify inconsistencies and explore reproductive allocation and cost concepts, as well as current trends in bryophyte reproduction. We examined different approaches and highlighted advantages and limitations. We emphasized five key topics: the importance of understanding reproductive allocation and reproductive cost in bryophytes; the significance of bryophytes as model organisms; historical research; terminological and methodological inconsistencies; sexual dimorphism and reproductive allocation; and measurement methods. Furthermore, we provided insights into future perspectives. Based on our findings, we advocate for standardized quantification of reproductive allocation. Standardization would enhance comparability and synthesis of results, ultimately advancing our understanding of reproductive allocation and cost of reproduction in bryophytes. Keywords Biomass Allocation * Liverworts * Moss * Reproductive Effort * Reproductive Investment * Trade-off, Introduction Life history theory, an approach that investigates the timing of key events in an organism's life cycle, predicts that every resource produced by an organism is allocated to its [...]

Asteraceae are among the most abundant angiosperm families on oceanic islands. The reproductive biology of Asteraceae is reviewed and the attributes of the family contributing to their success on islands are discussed. Asteraceae are effective dispersers (the small, single-seeded fruits are moved great distances by wind and birds), and colonization is most likely limited by establishment. The pollinators of the colonizing ancestors rarely disperse with them to islands. Divorced from the pollinators of their ancestral habitats, the capitulum of aggregated small, shallow flowers typical of Asteraceae facilitates pollination of colonizers by various novel biotic visitors and by wind. Self-compatible (SC) colonizing ancestors are common, permitting establishment of sexual populations from one or few propagules. However, several large insular lineages of Asteraceae originated from functionally self-incompatible (SI) colonizers that may have also possessed the capacity to set some self-seed. Establishment may also be facilitated by dominance relationships among S-alleles in the sporophytic SI (SSI) system of Asteraceae, increasing cross-compatibility within small populations. Factors potentially promoting outcrossing in SC Asteraceae are: gynomonoecy, with temporal separation of receptive pistillate ray florets and pollen presentation in the hermaphroditic disc florets of a capitulum (interfloral protogyny); and intrafloral protandry where pollen presentation occurs before stigmata become receptive. Dioecy, gynodioecy, and monoecy are infrequent sexual systems in insular Asteraceae. Multiple paternity is similar in island composites to other Asteraceae, suggesting that neither compatible mates nor pollinators are typically limiting. Additional studies, particularly with genomic markers, are needed for more refined insights into mating systems and paternity in island Asteraceae as these results have important conservation implications. Keywords Asteraceae * Conservation biology * Oceanic islands * Reproductive biology, Introduction Flowering plants face multiple challenges in dispersal, establishment, and diversification in oceanic archipelagos (Baker, 1955; Carlquist, 1974, chapts. 1,2, 3, 11, 13; Pannell, 2015; Pannell et al., 2015). Despite [...]

The significance of maternal and progeny environment to chasmogamy (CH) and cleistogamy (CL) in perennial plants is not well known. The perennial grass Danthonia compressa produces CH spikelets capable of outcrossing on terminal panicles in summer followed by selling axillary CL spikelets in autumn. This study compared CH and CL seed mass, germination, seedling size, tillering, and reproduction in a sunny woodland edge and shaded interior habitat in the Catskill Mountains of New York State. CL seeds were significantly heavier than CH seeds. Numbers and mass of both seed types were greater in the edge. CL seeds showed much greater germination than CH seeds in both environments during spring, 2018; CL seedlings were larger than CH seedlings in the sunnier habitat. Survival was much greater in the edge than interior and higher for CL seedlings. After 27 months, maternal effects were mostly not detected and there was no significant effect of plant type (CH vs CL) on tiller production, final biomass, or reproduction via CH and CL. For this native grass, non-dispersed CL seeds may be more critical to seedling establishment and population persistence due to greater mass and germinability, and better plant survival, relative to smaller, dispersible CH seeds. Key words: Cleistogamy, light, maternal effects, mixed mating system, perennial grass, Poaceae, Introduction Cleistogamy (CL) is the production of closed, self-fertilizing flowers and occurs in almost 700 angiosperm species distributed among 50 plant families (Culley and Klooster 2007). Early descriptions of CL [...]

The reproductive ecology of the semi-serotinous species black spruce (Picea mariana (Mill.) BSP) in northern boreal forests remains poorly understood. There is a general lack of data on cone/seed production and viability as a function of biotic treelevel characteristics and abiotic variables. No studies currently exist to quantify these differences over a large gradient in temperature, elevation, and precipitation. Extensive physical, ecological, dendrometric, and reproductive data were collected from young to very old black spruce stands in northern Quebec. ANOVA and general linear mixed models were used to examine interannual cone production, and the relative importance of the biotic and abiotic explanatory factors in determining total cone production; length of the cone-bearing zone; filled seeds per cone; proportion of filled seeds; and seed viability. The results illustrate that the reproductive ecology of black spruce in northern cold forests is mainly explained by biotic variables such as age and diameter [DELTA]T breast height, and by abiotic variables related to temperature such as elevation, length of the growing season, and growing degree-days. Black spruce exhibits a lower reproductive potential in northern cold forests, making it possibly less resilient to increased fire frequency, particularly in unproductive and very young or very old stands. Key words: black spruce, reproductive ecology, cone production, seed production, germination, boreal forest, forest fire, seed viability, resilience, adaptation L'ecologie de la reproduction de l'espece semi-serotineuse, l'epinette noire (Picea mariana (Mill.) BSP) dans les forets boreales froides est encore peu documentee. Il existe un manque general de donnees sur la production des cones/graines et leur viabilite en fonction des caracteristiques biotiques au niveau de l'arbre et des variables abiotiques. Aucune etude n'existe actuellement pour quantifier ces differences sur un large gradient de temperature, d'altitude, et de precipitations. De nombreuses donnees physiques, ecologiques, dendrometriques et reproductives ont ete recueillies dans des peuplements d'epinette noire jeunes a tres ages dans le nord du Quebec. Des ANOVA et des modeles mixtes lineaires generaux ont ete utilises pour examiner la production annuelle de cones et l'importance relative des facteurs explicatifs biotiques et abiotiques dans la determination de la production totale de cones; la longueur de la cime comportant des cones; le nombre de graines pleines par cone; la proportion de graines pleines; et leur taux de germination. Les resultats indiquent que l'ecologie de la reproduction de l'epinette noire dans les forets boreales nordiques est expliquee par des variables biotiques telles que l'age et le DHP, et des variables abiotiques liees a la somme thermique regionale telles que l'altitude, la duree de la saison de croissance, et les degres-jours de croissance. L'epinette noire presente un potentiel reproductif plus faible dans les forets froides du nord, ce qui la rend moins resistante a l'augmentation de la frequence des feux, particulierement dans les peuplements improductifs et tres jeunes ou tres vieux. Mots-cles : epinette noire, ecologie de la reproduction, production des cones, production des graines, germination, foret boreale, feu de foret, taux de germination, resilience, adaptation, 1. Introduction Black spruce (Picea mariana (Mill.)) is one of the most common and commercially important conifer species in the boreal forest of eastern North America (Viereck and Johnston 1990), [...]

Sub-Antarctic giant kelp (Macrocystis pyrifera) forests have remained relatively wild and far from anthropogenic pressures. However, they are increasingly exposed to multiple stressors that might affect kelp forest persistence. The urban impact of a coastal city, Ushuaia (54° S 68° W), in the Beagle Channel, Argentina, on giant kelp forest environments was evaluated in this study and implications on morphological variability were explored. Seasonal samplings were conducted from 2019 to 2021 in two contrasting sites: an urban site directly exposed to coastal discharges, and a non-urban site. Our results indicate that the combination of coastal discharges, kelp canopy and low wave exposure increases light attenuation inside kelp forests, promoting coastal darkening. Additionally, and based on the present results, we present the first record of algal turf in the Beagle Channel. We further propose the Kelp Structure Index to describe the effect of environmental conditions on kelp structure, which highlights an increased blade surface in sites with urban impacts. These results suggest that giant kelp shows high plasticity in morphological traits under varying environmental conditions, particularly in environments exposed to coastal darkening effects. However, the presence of turf indicates that urban pressures might be severely limiting kelp forest health., Author(s): Julieta Kaminsky [sup.1] , María Bagur [sup.1] , Irene Ruth Schloss [sup.1] [sup.2] [sup.3] , Soledad Diodato [sup.1] [sup.2] , Mariano Rodríguez [sup.2] , Alejandro H. Buschmann [sup.4] , [...]

Heliotropism of flowers is thought to provide a reproductive advantage to individuals of many species; yet, there are few clear demonstrations of a fitness advantage provided by heliotropism, most of which are almost completely restricted to plants from the arctic or alpine regions where a heat gain provides an advantage to the plants. In this study, we report heliotropism in the white trillium, an early spring blooming species from the temperate forests of eastern North America. The white trillium shows horizontal seasonal heliotropism with flowers mainly facing south throughout the summer, but it also exhibits daily horizontal and vertical heliotropism with the orientation of the flower tracking the sun during the day. The study of 479 tethered plants indicated that seasonal heliotropism provides a reproductive advantage to the white trillium, with south-facing individuals showing a 12% increase in fertilized ovules compared to north-facing plants. The ecology of this long-lived perennial is, in many aspects, similar to that of alpine and arctic heliotropic species. Indeed, white trilliums are insect-pollinated and they flower when the weather is cold, before the trees leaf out. This suggests that there are potentially more species for which heliotropism is advantageous amongst early spring flowers from the temperate forest. Key words: heliotropism, white trillium, fertilized ovules, fitness, plant reproduction On pense que l'heliotropisme des fleurs procure un avantage reproductif aux individus de nombreuses especes. Pourtant, il existe peu de demonstrations claires de l'avantage de 1'heliotropisme sur le plan de la valeur adaptative, et ces demonstrations sont presque toutes limitees aux plantes des regions arctiques ou alpines, ou un gain de chaleur procure un avantage aux plantes. Dans cette etude, nous decrivons 1'heliotropisme chez le trille blanc, une espece a floraison printaniere precoce des forets temperees de Test de l'Amerique du Nord. Le trille blanc montre un heliotropisme saisonnier horizontal avec des fleurs principalement orientees vers le sud tout au long de l'ete, mais il presente egalement un heliotropisme horizontal et vertical quotidien avec l'orientation de la fleur suivant le soleil pendant la journee. L'etude de 479 plantes attachees a indique que 1'heliotropisme saisonnier procure un avantage reproductif au trille blanc, les individus orientes vers le sud presentant une augmentation de 12 % d'ovules fecondes par rapport aux plantes orientees vers le nord. L'ecologie de cette plante vivace a longue duree de vie est, sous de nombreux aspects, similaire a celle des especes heliotropes alpines et arctiques. En effet, les trilles blancs sont pollinises par les insectes et ils fleurissent lorsque le temps est froid, avant l'apparition du feuillage des arbres. Cela suggere qu'il y a potentiellement plus d'especes pour lesquelles 1'heliotropisme est avantageux parmi les fleurs printanieres precoces de la foret temperee. [Traduit par la Redaction] Mots-cles : heliotropisme, trille blanc, ovules fecondes, valeur adaptative, reproduction vegetale, Introduction The heliotropism of flowers has attracted curiosity and interest amongst evolutionary ecologists for more than 50 years (Hocking and Sharplin 1965; Hocking 1968; Kevan 1972, 1975). Heliotropism is the [...]

Abstract Apomixis is considered to be a natural mode of clonal propogation from seed to seed, in which progeny serves as a replica of maternal genotype. The process evades creation [...]

Phenology is an ecologically critical attribute that is commonly coordinated with other plant traits. Phenological shifts may be the result of evolutionary adjustments to persistently new conditions, or they may be transitory, varying with annual fluxes in abiotic conditions. In summer-dry, fire-prone Mediterranean-type climates, for example, many plant lineages have historically migrated from forests to more arid shrublands resulting in adaptive trait changes. These shifts in habitat abiotic conditions and biotic interactions influence morphology of flowers and fruits and interact with phenological timing. The Arbutoideae (Ericaceae) is one lineage that illustrates such modifications, with fruit characters evolving among genera from fleshy to dry fruit, thin to stony endocarps, and bird to rodent dispersal, among other changes. We scored herbarium collections and used ancestral trait analyses to determine phenological shifts among the five Arbutoid genera found in semi-arid climates. Our objective was to determine if phenology shifts with the phylogenetic transition to different reproductive characters. Our results indicate that phenological shifts began with some traits, like the development of a stony endocarp or dry fruits, but not with all significant trait changes. We conclude that early phenological shifts correlating with some reproductive traits were permissive for the transition to other later character changes. Key words: Ericaceae, fire regime, obligate seeding, scatter-hoarding, seed predation. La phenologie est un attribut critique d'un point de vue ecologique qui est generalement coordonne avec d'autres traits des vegetaux. Les changements phenologiques peuvent etre le resultat d'ajustements evolutifs a de nouvelles conditions persistantes, ou transitoires, qui varient avec le flux annuel des conditions abiotiques. Dans les climats mediterraneens secs en ete et sujets aux incendies, par exemple, de nombreux lignages de vegetaux ont historiquement migre des forets vers des zones arbustives plus arides, entrainant des changements en matiere de traits adaptatifs. Ces changements dans les conditions abiotiques de l'habitat et les interactions biotiques influencent la morphologie des fleurs et des fruits et interagiront avec le calendrier phenologique. Les Arbutoideae (Ericaceae) constituent un lignage qui illustre de telles modifications, les caracteres des fruits evoluant parmi les genres, de fruits charnus a secs, d'endocarpes minces a pierreux, et de dispersion par les oiseaux a une dispersion par les rongeurs, entre autres changements. Les auteurs ont analyse des collections d'herbiers et utilise l'analyse de traits ancestraux pour caracteriser les changements phenologiques parmi les cinq genres d'Arbutoides trouves dans des climats semi-arides. Leur objectif consistait a determiner si la phenologie change avec la transition phylogenetique vers des caracteres reproducteurs differents. Leurs resultats indiquent que les changements phenologiques ont commence avec certains traits, comme le developpement d'un endocarpe pierreux ou de fruits secs, mais pas avec tous les changements de traits significatifs. Ils concluent que les changements phenologiques precoces en correlation avec certains caracteres reproducteurs etaient permissifs pour la transition vers d'autres changements de caracteres ulterieurs. [Traduit par la Redaction] Mots-cles : Ericaceae, regime des incendies, semis obligatoire, eparpillement, predation des graines., Introduction Phenological changes that occur in coordination with fruit types is an understudied dimension of fruit evolution compared with dispersal or other traits (Forrest and Miller-Rushing 2010). Most studies investigating [...]

Phenological responses of plants to temperature dynamics are receiving attention due to the ongoing challenge with climate change. Most previous phenological studies have focused on flowering phenology rather than fruiting phenology. However, at mid-latitudes, the air temperature periodically changes during the growing period of plants. Hence, cool temperatures early and late in the growing period may affect reproductive success through pollination and fruit-development processes. To evaluate the linkages between reproductive phenology and success, we compared the phenologies, photosynthetic capacities, and fruit-set rates among 25 species within a cooltemperate community in northern Japan. The ambient temperature during the flowering periods of individual species increased with delays in flowering-onset time, whereas the ambient temperature during fruit-development periods was highest for species which bloomed in July. Fruit-set success among species was positively correlated with the ambient temperatures during the reproductive periods and with the photosynthetic capacity. Fruit production of early blooming species was limited by cool temperatures during the flowering period, presumably because of low pollinator activity, whereas that of late-blooming species was limited by cool temperatures during the fruit-development period because of slow fruit-development (i.e., sink limitation). Thus, limiting factors of fruit production varied depending on the flowering phenology of individual species within a community. Key words: air temperature, pollen limitation, pollinator, seasonality, sink limitation. Les réponses phénologiques des plantes à la dynamique de la température font l'objet d'une attention particulière en raison des changements climatiques en cours. La plupart des études phénologiques précédentes se sont concentrées sur la phénologie de la floraison plutôt que sur la phénologie de la fructification. Toutefois, aux latitudes moyennes, la température de l'air change périodiquement pendant la période de croissance des plantes. Par conséquent, des températures fraîches au début et à la fin de la période de croissance peuvent affecter le succès de la reproduction à travers les processus de pollinisation et de développement des fruits. Afin d'évaluer les liens entre la phénologie et le succès de la reproduction, les auteurs ont comparé les phénologies, les capacités photosynthétiques et les taux de fructification de 25 espèces à l'intérieur d'une communauté tempérée froide du nord du Japon. La température ambiante pendant les périodes de floraison des espèces individuelles augmentait avec le retard de l'apparition de la floraison, tandis que la température ambiante pendant les périodes de développement des fruits était la plus élevée pour les espèces qui fleurissaient en juillet. Le succès de la fructification des différentes espèces était positivement corrélé avec les températures ambiantes pendant les périodes de reproduction et avec la capacité photosynthétique. La production de fruits des espèces à floraison précoce était limitée par les températures fraîches pendant la période de floraison, probablement en raison de la faible activité des pollinisateurs, tandis que celle des espèces à floraison tardive était limitée par les températures fraîches pendant la période de développement des fruits en raison de la lenteur du développement des fruits (c'est-à-dire la limitation du puits). Ainsi, les facteurs limitants de la production de fruits varient en fonction de la phénologie de floraison des espèces individuelles au sein d'une communauté. [Traduit par la Rédaction] Mots-clés : température de l'air, limitation du pollen, pollinisateur, saisonnalité, limitation du puits., Introduction When should plants bloom and develop fruits? This issue is critical for plants to adapt to local abiotic and biotic environments, and it is one of their most important [...]

Masting behavior--variable and synchronized reproduction by a population of plants--has long been recognized as correlating with weather. How and why weather conditions influence seed production is, however, poorly understood. We investigated the relationships between acorn production and both local weather and long-term climate in 10 populations across the geographic range of the valley oak (Quercus lobata Nee), a California endemic that matures acorns in a single season. Acorn production was larger following a cold spring in the prior year and dry conditions in the winter and spring immediately preceding acorn maturation; similar patterns were also found, with minor differences, at all 10 individual sites. The strength of the relationships varied geographically in the case of the correlation between winter rainfall and annual acorn production, which was stronger (more negative) at wetter sites. Thus, in contrast to a recent study in Quercus petraea (Matt.) Liebl., weather had generally similar effects on acorn production throughout the range of Q. lobata. Similar to Q. petraea, however, the strength of the relationship between site-level annual acorn production and one of the weather factors affecting acorn production (winter rainfall in the case of Q. lobata) varied geographically in ways that may be related to differences among sites in the degree of pollen limitation. Understanding the mechanisms by which weather affects seed production is challenging but critical if we are to understand how climate change will affect masting behavior in the future. Key words: acorn production, masting, Quercus lobata, valley oak, variable reproduction. Il est depuis longtemps reconnu que la reproduction synchronisee et variable dans une population de plantes (<>) est correlee avec les conditions meteorologiques. Cependant, on comprend mal comment et pourquoi les conditions meteorologiques influencent la production de semences. Nous avons etudie les relations entre la production de glands et les conditions meteorologiques locales ainsi que le climat a long terme chez 10 populations dans l'aire de repartition du chene lobe (Quercus lobata Nee), un chene endemique de la Californie dont les glands arrivent a maturite en une seule saison. La production de gland etait plus abondante a la suite d'un printemps froid l'annee precedente et des conditions seches durant l'hiver et le printemps precedant immediatement la maturation des glands. Des patrons similaires ont ete observes, avec des differences mineures, dans l'ensemble des 10 stations individuelles. La force de la relation variait geographiquement dans le cas de la correlation entre la chute de pluie hivernale et la production annuelle de glands; la correlation etait plus forte (plus negative) dans les stations plus humides. Par consequent, contrairement a une etude recente qui portait sur Quercus petraea (Matt.) Liebl., les conditions meteorologiques avaient generalement des effets similaires sur la production de glands partout dans l'aire de repartition de Q. lobata. Comme avec Q. petraea cependant, la force de la relation entre la production annuelle de glands a l'echelle de la station et un des facteurs meteorologiques qui influencent la production de glands (chute de pluie hivernale dans le cas de Q. lobata) variait d'un endroit a l'autre. Cette variation pouvait etre reliee a des differences entre les stations concernant la disponibilite du pollen. Il est difficile mais essentiel de comprendre les mecanismes par lesquels les conditions meteorologiques influencent la production de semences si nous voulons comprendre de quelle facon le changement climatique affectera la reproduction synchronisee dans le futur. [Traduit par la Redaction] Mots-cles: production de glands, masting, Quercus lobata, vallee du chene, reproduction variable., Introduction Variable, synchronized seed production, known as mast-fruiting or masting behavior, is commonly observed in many taxa of plants and is particularly widespread among temperate and boreal trees. The evolutionary [...]

Species that propagate by sexual reproduction actively guard against the fertilization of an egg by multiple sperm (polyspermy). Flowering plants rely on pollen tubes to transport their immotile sperm to fertilize the female gametophytes inside ovules. In Arabidopsis, pollen tubes are guided by cysteine-rich chemoattractants to target the female gametophyte.sup.1,2. The FERONIA receptor kinase has a dual role in ensuring sperm delivery and blocking polyspermy.sup.3. It has previously been reported that FERONIA generates a female gametophyte environment that is required for sperm release.sup.4. Here we show that FERONIA controls several functionally linked conditions to prevent the penetration of female gametophytes by multiple pollen tubes in Arabidopsis. We demonstrate that FERONIA is crucial for maintaining de-esterified pectin at the filiform apparatus, a region of the cell wall at the entrance to the female gametophyte. Pollen tube arrival at the ovule triggers the accumulation of nitric oxide at the filiform apparatus in a process that is dependent on FERONIA and mediated by de-esterified pectin. Nitric oxide nitrosates both precursor and mature forms of the chemoattractant LURE1.sup.1, respectively blocking its secretion and interaction with its receptor, to suppress pollen tube attraction. Our results elucidate a mechanism controlled by FERONIA in which the arrival of the first pollen tube alters ovular conditions to disengage pollen tube attraction and prevent the approach and penetration of the female gametophyte by late-arriving pollen tubes, thus averting polyspermy. FERONIA prevents polyspermy in Arabidopsis by enabling pectin-stimulated nitric oxide accumulation at the filiform apparatus after the first pollen tube arrives, which disengages LURE1 chemoattraction to prevent late-arriving pollen tubes from entering the ovule., Author(s): Qiaohong Duan [sup.1] [sup.2] , Ming-Che James Liu [sup.1] [sup.3] , Daniel Kita [sup.1] [sup.4] [sup.7] , Samuel S. Jordan [sup.1] , Fang-Ling Jessica Yeh [sup.1] , Robert Yvon [...]

Silene latifolia Poiret of Eurasia has established in North America, prompting this structural study of its mature unisexual buds and flowers. Floral nectaries, anther and stigma changes, and vestigial reproductive structures were studied using light and scanning electron microscopy. In staminate flowers, anthers dehisced before anthesis and >90% of their pollen was liberated within 36 h. Accumulated in the tubular calyx, nectar descended an anthophore from the stomatal-bearing nectary at the stamen bases. Nectary tissue surrounded the pistillode, a central filamentous organ lacking ovules but tipped by hairs resembling stigmatic papillae. In pistillate flowers, nectar flowed into an inflated calyx. The annular nectary had 10 regularly spaced, stomatal-lined craters and was continuous with the adaxial surfaces of the infertile antisepalous and epipetalous staminodes. Key elements of entomophilous pollination leading to successful sexual reproduction of this invasive species include secondary nectar presentation from disparate floral nectaries that, for pistillate flowers, also incorporate the staminodes; rapid pollen release from anthers; and elongation of papillae by tip growth that enhances each stigma's receptive surface. Context is also provided for future studies of floral nectary development in this model dioecious species. Keywords: anther, dioecy, floral nectary, invasive species, pistillode, staminode, stigma, nectary stomata, unisexual flowers. Silene latifolia Poiret d'Eurasie s'est établie en Amérique du Nord, incitant de ce fait les auteurs à réaliser cette étude structurale de ses bourgeons et ses fleurs matures unisexuées. Les changements des nectaires floraux, des anthères et des stigmates, et les structures reproductives vestigiales ont été étudiés en microscopie optique et en microscopie électronique à balayage. Chez les fleurs staminées, les anthères entraient en déhiscence avant l'anthèse et >90% de leur pollen était libéré en moins de 36 h. Accumulé dans le calice tubulaire, le nectar amenait un anthophore du nectaire portant les stomates vers les bases des étamines. Le tissu du nectaire entourait le pistillode, un organe filamenteux central dépourvu d'ovules, mais portant des poils ressemblant à des papilles stigmatiques. Chez les fleurs pistillées, le nectar s'écoulait dans un calice gonflé. Le nectaire annulaire comportait dix creux régulièrement espacés, bordés de stomates et il était continu avec des surfaces adaxiales de staminodes infertiles antisépales et épipétales. Les éléments clés de la pollinisation entomophile donnant lieu à une reproduction sexuée fructueuse chez cette espèce envahissante comprennent la présentation de nectar secondaire à partir de nectaires floraux disparates qui, chez les fleurs pistillées, intègrent aussi les staminodes; une libération rapide de pollen à partir des anthères et l'élongation des papilles par une croissance apicale qui accroît la surface réceptrice de chaque stigmate. Les auteurs contextualisent aussi les études futures du développement des nectaires floraux grâce à ce modèle d'espèce dioïque. [Traduit par la Rédaction] Mots-clés : anthère, dioécie, nectaire floral, espèce envahissante, pistillode, staminode, stigmate, stomate du nectaire, fleurs unisexuées., Introduction Only 6% of angiosperm species feature dioecy (Renner and Ricklefs 1995), an extreme strategy for sexual reproduction, being reliant on proximity of male and female plants, synchronicity in flowering [...]

Abstract: Distylous species typically experience self-incompatibility with one morph often having partial selfcompatibility Small populations may therefore experience greater rates of selfing/intramorph crosses leading to skewed morph ratios and reduced [...]

Flower size is a key trait in the reproductive ecology of animal-pollinated plants. However, pollinator-mediated selection does not always modulate this trait and environmental conditions and/or antagonist interactions may favor smaller flowers. We evaluate the occurrence of a large-flowered family in a hot and dry Mediterranean environment, mediated by a cost-benefit balance and a male-female conflict. Large flowers have sizeable benefits in terms of pollination and reproductive success and pollinators mediate selection through male function, but female fitness is context-dependent. High floral production and maintenance costs and florivore incidence in large flowers limit female function, which counteracts pollinator-mediated selection. Large flowers are highly costly in the Mediterranean and flower size is mediated by a sexual conflict between the benefits of male function and the costs of the female one. However, a short floral longevity, occasional pollen limitation and selection through maleness keep the existence of large flowers in these environments. Keywords Cistaceae * Floral costs * Flower size * Pollinators * Male fitness * Female fitness, Introduction Animal-pollinated plants include a large diversity of flowers, varying in color spectrum, shape and design, scent, longevity, size and display. Historically, numerous botanists and evolutionary biologists have greatly been [...]

Recent concern regarding the potential decline of quaking aspen (Populus tremuloides Michx.) forests in the western United States has sparked concern over whether the species can be effectively regenerated. Using a retrospective approach, we quantified the response of regenerating aspen stems to an ordinary set of silvicultural treatments conducted over approximately the past decade in southern Utah, USA. A suite of variables describing stand structure and composition, stand vigor, physiographic factors, herbivore pressure, and treatment types were measured to predict the possible controls, as well as their relative importance, on aspen regeneration. Results suggested that aspen regeneration was most strongly related to browsing pressure, site preparation technique, and the presence of advance reproduction before treatment, which is a novel finding. Secondary predictors included elevation, site index, and overstory conditions, which are generally characteristics of stand vigor. Management recommendations based on our results should recognize the strong primary control that browsing pressure exerts on regeneration. First, the height of advance reproduction is inherently dependent on antecedent herbivory and also indicative of present browsing and should be assessed before treatment. Second, the most effective site preparation techniques, namely broadcast burning and browsing reduction, will directly reduce browsing pressure, assuming ungulate populations are not too large. Any management targeting timely and effective aspen regeneration should incorporate monitoring and (or) controlling browsing pressure, both before and after treatment. Key words: browsing, coppice, herbivory, Populus tremuloides, silviculture. L'inquietude recente face au deperissement apprehende des forets de peuplier faux-tremble (Populus tremuloides Michx.) dans l'ouest des Etats-Unis a suscite un questionnement concernant la possibilite de regenerer efficacement cette espece. A l'aide d'une approche retrospective, nous avons quantifie la reponse de tiges de peuplier faux-tremble au stade de la regeneration a un ensemble ordinaire de traitements sylvicoles realises au cours de la derniere decennie dans le sud de l'Utah, aux Etats-Unis. Une serie de variables decrivant la composition et la structure du peuplement, la vigueur du peuplement, les facteurs physiographiques, la pression des herbivores et les types de traitement ont ete mesurees dans le but de determiner quels facteurs pourraient influencer la regeneration du peuplier faux-tremble ainsi que leur importance relative. Les resultats indiquent que la regeneration du peuplier faux-tremble est surtout influencee par la pression des herbivores, la preparation technique du terrain, et la presence de regeneration preetablie, c'est-a-dire avant le traitement, ce qui constitue un resultat inedit. Les predicteurs secondaires incluent l'altitude, l'indice de qualite de station et l'etat de l'etage dominant: generalement les caracteristiques de vigueur du peuplement. Selon nos resultats, les recommandations d'amenagement devraient reconnaitre que la regeneration est controlee principalement par la pression des herbivores. Premierement, la hauteur de la regeneration preetablie depend intrinsequement du broutage passe mais peut aussi donner une idee de l'impact actuel du broutage; elle devrait etre evaluee avant d'appliquer un traitement. Deuxiemement, les techniques de preparation de terrain les plus efficaces: le brulage extensif et la reduction du broutage, reduiront directement la pression des herbivores a condition que les populations d'ongules ne soient pas trop importantes. Tout amenagement visant a etablir une regeneration en temps opportun et efficace du peuplier fauxtremble devrait comprendre le suivi ou le controle de la pression des herbivores, ou les deux, avant et apres le traitement. [Traduit par la Redaction] Mots-cles: broutage, taillis, herbivorisme, Populus tremuloides, sylviculture., Introduction Quaking aspen (Populus tremuloides Michx.; hereafter, aspen) is an ecologically and economically important forest species throughout its range (Baker 1925). A prevalent theme in the aspen literature is concern [...]

The differential temperature (ΔT) model, based on the assumption that masting plants respond to the difference in the temperatures during the growing seasons 1 and 2 years prior to seed production, has recently been proposed to explain the proximate factor of masting. In this study, we used a 28-year series of data on pollen cone and seed production in Cryptomeria japonica D. Don in Japan and compared several models based on temperatures and resources to test whether ΔT acts as a cue or is a proxy for resource limitation. Of all the models tested, models including ΔT, previous summer absolute temperature [T.sub.n-1], and reproduction in the previous year provided the best fit. The number of pollen cones and seeds produced was proportional to the difference in the mean daily maximum temperature during June to August between the preceding two years. In addition, to test whether the double mast events in consecutive years was less common than consecutive warm summers, we used our dataset and 12 datasets of pollen dispersal of 17 years or longer of C. japonica in Japan. Although consecutive warm summers occurred in 4.4% of pairs, double mast events occurred in 1.0%. The ΔT model was a considerably better predictor of the rare phenomenon of double mast events, which occur only after a specific sequence of cold-moderate-hot absolute summer temperatures. Thus, ΔT acts as cue for masting in C. japonica. Key words: climate cue, Cryptomeria japonica, ΔT model, Japanese cedar, masting. Le modele de temperature differentielle (ΔT), fonde sur l'hypothese que les plantes reagissent a la difference de temperature entre les deux saisons de croissance qui ont precede une annee semenciere, a recemment ete propose pour expliquer la cause directe de ce phenomene. Dans cette etude, nous avons utilise une serie de donnees portant sur 28 annees de production de cones males et de graines chez Cryptomeria japonica D. Don au Japon et nous avons compare plusieurs modeles fondes sur les temperatures ainsi que les ressources pour verifier si le modele ΔT agit comme un signal ou est un indice de ressources limitees. De tous les modeles testes, les modeles qui incluaient ΔT, la temperature absolue de l'ete precedent [T.sub.n-1] et la reproduction au cours de l'annee precedente donnaient le meilleur ajustement. Le nombre de cones males et de graines produits etait proportionnel a la difference de temperature journaliere maximum moyenne durant les mois de juin et aout entre les deux annees precedentes. De plus, pour determiner si les annees semencieres doubles consecutives etaient moins frequentes que les etes chauds consecutifs, nous avons utilise notre base de donnees et 12 bases de donnees sur la dispersion du pollen sur 17 annees ouplus pour C. japonica au Japon. Bienque des etes chauds consecutifs soient survenus dans 4,4% des paires, les annees semencieres doubles sont survenues dans 1% des cas. Le modele ΔT predisait beaucoup mieux le phenomene rare des annees semencieres doubles qui survenaient seulement a la suite d'une sequence specifique de temperatures estivales absolues: froides-moderees-chaudes. Par consequent, ΔT agit comme un signal pour les annees semencieres chez C. japonica. [Traduit par la Redaction] Mots-cles: signal climatique, Cryptomeria japonica, modele ΔT, cedre du Japon, annee semenciere., Introduction Population-level fluctuations of large crops of seeds or flowers, known as masting or mass flowering, are common and important phenomena in plants (Silvertown 1980, Kelly and Sork 2002). Masting [...]

Diploid Daucus pusillus Michx. (x = 11) and hexaploid Daucus montanus Humb. et Bonpl. ex Schult. (x = 11) are wild taxonomic carrot species, closely related to diploid Daucus carota L. (x = 9), spontaneous in Argentina. For efficient ex situ conservation and potential use in breeding, we investigated their reproductive behavior by (i) carrying out controlled pollinations among D. pusillus accessions from a wide distribution area in the country and between these and one plant of D. montanus that overlapped in flowering, and (ii) bagging a few inflorescences to prevent outcrossings. Part of the pollinated pistils were analyzed by fluorescence microscopy; others were left on the plant. Pollen viability was high (>87%) in all accessions, but heterogeneity for size and shape was observed. Seed formation in bagged inflorescences confirmed that D. pusillus is autogamous and revealed that D. montanus is self-compatible. Fully developed mericarps were obtained only in intraspecific combinations. It is concluded that populations classified as the taxonomic species D. pusillus constitute a biological species as well, and that they are closely related to the taxonomic species D. montanus because they share the basic chromosome number and are reproductively isolated mainly by post-zygotic barriers, which could be eventually circumvented via 2n gametes. Key words: hybridization, breeding barriers, taxonomic species, biological species. Resume: Daucus pusillus Michx. (x = 11) diploide et Daucus montanus Humb. et Bonpl. ex Schult. (x = 11) hexaploide sont des especes taxonomiques de carottes sauvages, etroitement reliees a Daucus carota L. (x = 9) diploide, spontanee en Argentine. Les auteurs ont examine leurs comportement reproducteur a des fins de conservation efficiente ex situ et d'utilisation potentielle en reproduction, (i) en realisant des pollinisations controlees parmi des accessions de D. pusillus provenant d'une large zone de distribution dans le pays, et entre elles et un plant de D. montanus dont les floraisons se chevauchaient, et (ii) en enveloppant quelques inflorescences afin de prevenir les croisements heterogenes. Une partie des pistils pollinises ont ete analyses par microscopie en fluorescence, les autres etant laisses sur la plante. La viabilite du pollen etait elevee (>87 %) chez toutes les accessions, mais une heterogeneite sur le plan de la taille et de la forme a ete observee. La grenaison des inflorescences enveloppees a confirme que D. pusillus est autogame et revele que D. montanus est auto-compatible. Des mericarpes pleinement developpes ont ete obtenus uniquement lors de combinaisons intraspecifiques. Les auteurs concluent que les populations attribuees a l'espece taxonomique D. pusillus constituent une egalement une espece biologique, et qu'elles sont etroitement reliees a l'espece taxonomique D. montanus car elles partagent le nombre de base de chromosomes et sont isolees sur le plan reproducteur principalement par des barrieres post-zygotiques, qui pourraient eventuellement etre contournees via un nombre diploide de gametes. [Traduit par la Redaction] Mots-cles: hybridation, barrieres reproductrices, espece taxonomique, espece biologique., Introduction Three to four wild Daucus species (according to different authors), closely related to the edible carrot (D. carota L.), have been reported in Argentina: naturalized Daucus carota L., Daucus [...]

The study of floral traits and pollination for the plant genus Phlox has historically been focused on either surveys of general pollinator affinities across the genus or detailed research on pollinator-mediated evolution of floral color in a single species (Phlox drummondii). The purpose of this study was to explore a different kind of trait--floral scent in Phlox divaricata, a species noted for its strong scent. Specifically, we predicted the diel emission patterns of floral scent might covary with the daily abundance of diurnal moths, identified in a previous study as the most important pollinators in a Konza Prairie population of P. divaricata. Consistent with this prediction, we documented peaks in median floral scent emissions at 1000-1200 and 1930-2130, coinciding with peaks in moth visitation and resulting seed production. Two groups of scent compounds contributed to this pattern; linalool and its associated lilac aldehyde/alcohol compounds (especially lilac aldehyde B) contributed a greater proportion to scent at 1000-1200, while aromatic compounds (including benzaldehyde and benzyl acetate) contributed a greater proportion to scent at 1930-2130 and other afternoon time periods. These volatiles are known floral attractants for several lepidopteran pollinators, including noctuid moths. However, there is an additional peak in pollinator abundance (Hemaris diurnal hawkmoths) and seed set at a time when scent production is relatively low (1400-1600) suggesting additional factors mediate both pollinator behavior and floral volatile emissions. Future studies of P. divaricata should test for the presence of destructive floral enemies that might be attracted by floral volatiles during mid-afternoon periods, as well as the importance of visual floral traits (color, shape) in attracting diurnal moths, an important functional group of pollinators that has received minimal attention in North America., INTRODUCTION Studies of unique floral forms and functions for a number of different plant species have led to a greater understanding of the evolutionary history of relationships between plants and [...]

Numerous factors contribute to the variability in treeline change; however, the potential role of insect predation in limiting seed productivity is not well documented. Conditions for seed germination, establishment, and survival are not limiting at the Mealy Mountains treeline (Labrador, Canada), but seedlings are rarely encountered, suggesting a seed-related bottleneck to recruitment. Mature cones were collected in 2008 from four tree species (black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.), balsam fir (Abies balsamea (L.) Mill.), eastern larch (Larix laricina (Du Roi) K. Koch), and white spruce (Picea glauca (Moench) Voss)) across three treeline zones (forest, transition, and krummholz) to assess potential seed limitation. During that year, an unexpectedly high diversity of insect larvae caused extensive reproductive loss and damaged the cones of ~85% of trees sampled, confirming that treeline change models should include seed predation. Seed germination was low and variable in all treeline zones, although significantly higher in black spruce and eastern larch. Most reproductive quality measures decreased significantly with elevation, although no differences among zones or tree species in the percentages of seeds damaged by insects were found (mean ± standard deviation: 31% [+ or -] 23%). Based on tree density and seed production, black spruce is predicted to lead the treeline expansion in the Mealy Mountains. Although climate warming may create conditions conducive for increased seed production, predispersal seed predation may limit future treeline expansion. Key words: climate change, forest-tundra ecotone, insect herbivory, multispecies, predispersal seed predation, reproductive bottleneck. Plusieurs facteurs contribuent a la variabilite de la modification de la limite des arbres mais le role potentiel des epidemies d'insecte dans la reduction de la productivite des graines a ete peu etudie. A la limite des arbres dans les montagnes Mealy (Labrador, Canada), les conditions sont adequates pour la germination, l'etablissement et la survie mais on trouve rarement des semis. Cela indique qu'il y a un probleme de recrutement relie aux graines. Des cones matures ont ete collectes en 2008 chez quatre especes (epicea noir (Picea mariana (Mill.) Britton, Sterns & Poggenb.), sapin baumier (Abies balsamea (L.) Mill.), meleze laricin (Larix laricina (Du Roi) K. Koch) et epicea blanc (Picea glauca (Moench) Voss)) dans trois zones de la limite des arbres (foret, transition et krummholz) pour evaluer les problemes potentiels relies aux graines. Durant cette annee, une diversite etonnamment elevee de larves d'insecte ont cause des pertes importantes en endommageant les cones d'environ 85 % des arbres echantillonnes. Cela a confirme que les modeles qui simulent les variations de la limite des arbres devraient inclure la predation par les insectes. La germination des graines etait faible et variable dans toutes les zones a la limite des arbres quoique significativement meilleure chez l'epicea noir et le meleze. La plupart des mesures de qualite de la reproduction diminuaient significativement avec l'altitude bien qu'aucune difference dans le pourcentage de graines endommagees par les insectes entre les zones ou les especes d'arbre n'ait ete observee (moyenne : 31% ± 23%ET). Sur la base de la densite des arbres et de la production de cones ou de graines, on prevoit que l'epicea noir dominera l'expansion de la limite des arbres dans les montagnes Mealy. Bien que le rechauffement du climat puisse creer des conditions favorables a l'augmentation de la production de graines, la predation des graines avant qu'elles n'aient ete dispersees pourrait limiter l'expansion future de la limite des arbres. [Traduit par la Redaction] Mots-cles : changements climatiques, ecotone entre la foret et la toundra, insectes herbivores, multiespeces, predation des graines avant leur dispersion, problemes de reproduction., Introduction At the global scale, upslope and northward advance of the thermally constrained forest-tundra ecotone (treeline; sensu Scott (1995)) is expected given projected warming scenarios associated with climate change (Grace [...]

Ranunculus ficaria is an invasive plant species in the northeastern United States, especially in urban riparian habitats. Changes in the frequency and intensity of flooding events in these urban riparian corridors create patches of heavy litter and patches of bare ground. Many plant species either cannot penetrate deep litter, or they are susceptible to freezing temperatures and drying conditions on bare ground. This can result in competitive advantages for invasive species that are adapted to these varying conditions. We conducted a field experiment to test the effects of leaf litter depth on R. ficaria biomass, bulbil production, flower production, and seed production under deep (20 cm) litter, intermediate (10 cm) litter, shallow (5 cm) litter, and bare ground along an urban stream in Louisville, Kentucky. Deep litter and lack of litter decreased plant biomass compared with shallow litter. Bulbil production was not significantly different across treatments. Flower and seed production were only reduced in deep litter. Ranunculus jicaria's ability to maintain production across a large range of litter depths may provide a competitive advantage over plant species not adapted to varying litter depths., INTRODUCTION Invasive plant species are important economic and environmental pests, posing threats to endangered species, altering native habitats, decreasing biodiversity, and facilitating the establishment of other invasive species (Pimentel et [...]

This article introduces the concept of 'robust selection', which proposes tree selection based on the stochastic simulation of economic values to account for the inherent uncertainty of economic weights used in tree selection for breeding programs. The proposed method uses both median ranking and ranking variability as criteria for breeding selection. Using consensus genetic and economic parameters from the New Zealand Radiata Pine Breeding Company program, we compare three selection strategies: deterministic application of economic weights from a vertically integrated bioeconomic model, an equal-weight index often used in operations, and robust selection. All strategies aim to increase value for a breeding objective that includes four traits, i.e., volume, stem sweep, branch size, and wood stiffness (measured as modulus of elasticity), based on a selection index that considers five criteria, i.e., stem diameter at breast height (1.3 m), straightness, branching score, wood density, and modulus of elasticity. Two-thirds of the selected trees were unique for each of the selection strategies. Robust selection achieved the best realised gain for three of the four selection criteria and was the middle performer in the last selection criteria. Considering the high intrinsic uncertainty of economic weights, we suggest that the relevant criterion for the selection of individuals is the maximum median ranking, subject to an acceptable level of variation in that ranking, rather than their narrow performance under a single economic scenario. This will lead to tree selections that perform well under a wide range of economic circumstances. Key words: breeding objectives, economic weights, simulation, economic evaluation, risk analysis. Cet article introduit le concept de << selection robuste >> qui propose une selection fondee sur la simulation stochastique de la valeur economique pour tenir compte de l'incertitude inherente du poids economique utilise pour la selection des arbres dans les programmes d'amelioration. La methode qui est proposee utilise le classement median et la variabilite du classement comme criteres pour la selection. A l'aide de parametres genetiques et economiques du programme de la New Zealand Radiata Pine Breeding Company qui font consensus, nous avons compare trois strategies de selection : l'application deterministique du poids economique provenant d'un modele bioeconomique verticalement integre, un indice de poids equivalent souvent utilise dans les operations et la selection robuste. Toutes les strategies visent a augmenter la valeur d'un objectif d'amelioration qui inclut le volume, la courbure du tronc, la dimension des branches et la rigidite du bois a partir d'un indice de selection qui tient compte du diametre du tronc, de sa rectitude, de la note de branchaison, de la densite du bois et du module d'elasticite. Les deux tiers des arbres selectionnes avec chacune des strategies etaient uniques. La selection robuste a produit le meilleur gain pour trois des quatre criteres de selection et occupe la position intermediaire pour l'autre critere. En tenant compte de l'importante incertitude intrinseque du poids economique, nous suggerons que le critere pertinent pour la selection des individus soit le classement median maximum, qui est sujet a un degre acceptable de variation dans ce classement, plutot que leur performance etroite dans le cadre d'un seul scenario economique. Cela va engendrer la selection d'individus qui performent bien dans une vaste gamme de conditions economiques. [Traduit par la Redaction] Mots-cles : objectifs d'amelioration, poids economique, simulation, evaluation economique, analyse de risques., Introduction The selection of superior trees is central to breeding programs, aiming to identify individuals with maximum economic-genetic value for a combination of characteristics of economic importance. These trees are [...]

Exponential fertilization has been shown to be a useful technique for improving seedling quality during nursery production. In this study, we evaluated (i) the impact of exponential vs. conventional fertilization on trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) seedlings during nursery production and (ii) the growth performance and nitrogen (N) utilization of those seedlings in response to foxtail barley (Hordeum jubatum L.) competition after the transplantation of seedlings in a greenhouse experiment. Exponential fertilization with an application rate higher than the conventional fertilization increased the internal N reserve in trembling aspen and white spruce seedlings during nursery production and also increased new leaf, new stem, and old stem biomass and N retranslocation rates in trembling aspen seedlings but not in white spruce seedlings after transplantation. Foxtail barley competition decreased N concentrations in seedlings and soil N uptake by the seedlings; however, increased N retranslocation rates with foxtail barley competition were observed in white spruce seedlings but not in trembling aspen seedlings. Our results suggest that the growth performance of seedlings was improved by N loading, whereas the impact of vegetation management was species specific. Key words: exponential fertilization, internal N reserve, N-loaded seedling, net N retranslocation rate, vegetation competition. La fertilisation exponentielle s'est averee utile pour ameliorer la qualite des semis lors de la production en pepiniere. Dans cette etude, nous avons evalue (i) l'impact de la fertilisation exponentielle vs conventionnelle sur les semis de peuplier faux-tremble (Populus tremuloides Michx.) et d'epicea blanc (Picea glauca (Moench) Voss) lors de la production en pepiniere, et (ii) la croissance de ces semis et leur utilisation de N en reaction a la competition de l'orge queue-d'ecureuil (Hordeum jubatum L.) apres les avoir transplantes en serre suivant un dispositif experimental. La fertilisation exponentielle, dont le taux d'application est plus eleve que la fertilisation conventionnelle, a augmente les reserves internes de N chez les semis de peuplier faux- tremble et d'epicea blanc durant la production en pepiniere et a augmente la biomasse des nouvelles feuilles, des nouvelles et des vieilles tiges ainsi que le taux de retranslocation de N apres la transplantation chez les semis de peuplier faux-tremble mais pas chez les semis d'epicea blanc. La competition de l'orge queue-d'ecureuil a reduit les concentrations de N dans les semis et l'absorption de N dans le sol par les semis; cependant, en presence de l'orge queue-d'ecureuil une augmentation du taux de retranslocation de N a ete observee chez les semis d'epicea blanc mais pas chez les semis de peuplier faux-tremble. Nos resultats indiquent que la croissance des semis a ete amelioree par une surcharge de N tandis que l'impact de la maitrise de la vegetation dependait de chaque espece. [Traduit par la Redaction] Mots-cles : fertilisation exponentielle, reserves internes de N, semis surcharges en N, taux net de retranslocation, competition de la vegetation., Introduction Vegetation management is one of the most critical silvicultural practices for maximizing postplanting tree seedling survival and growth during the early establishment phase of plantations (Lowery et al. 1993; [...]

Self-fertilization can facilitate the colonization of new habitats because it allows a single individual to found a population. Here we investigated the relationship between mating systems and colonization in hay-scented fern (Dennstaedtia punctilobula (Michx.) T.Moore). Throughout eastern North America, this species has been called a 'native invasive' for its tendency to dominate forest understories disturbed by logging, inhibiting tree regeneration. Thus, it is important to understand the mechanisms of its spread. We hypothesized that if populations were founded through selfing, then populations disturbed more recently would retain higher selfing ability; this pattern would demonstrate an important link between mating systems and colonization. For four populations logged at different times in the past, we compared the sporophyte production of gametophytes at different levels of inbreeding (intragametophytic selfing, intergametophytic selfing, and outcrossing) using laboratory crosses. Across all treatments, only 9.8% of gametophytes formed sporophytes (N = 400 gametophytes). Neither inbreeding level nor time since disturbance affected sporophyte production. Selfing ability did not differ across populations logged at different times; there was no interaction between inbreeding level and time since disturbance. The low reproductive success of D. punctilobula, regardless of inbreeding level or time since disturbance, suggests that population establishment and expansion via sexual reproduction may be relatively rare in this clonal species. Key words: inbreeding depression, invasive species, mating systems, reproductive assurance, self-fertilization. L'auto-fertilisation peut faciliter la colonisation de nouveaux habitats car elle permet a un seul individu de fonder une population. Les auteurs ont examine ici la relation entre les systemes de croisement et la colonisation de la fougere odorante (Dennstaedtia punctilobula (Michx.) T.Moore). A travers tout l'est de l'Amerique du Nord, cette espece a ete identifiee comme indigene envahissante a cause de sa tendance a dominer les sous-etages forestiers perturbes par l'exploitation forestiere, inhibant la regeneration des arbres. Il est alors important de comprendre les mecanismes de sa dissemination. Les auteurs ont emis l'hypothese que si des populations etaient fondees par autofecondation, alors les populations perturbees plus recemment pourraient conserver plus longtemps leur capacite d'autofecondation; ce patron demontrerait un lien important entre les systemes de croisement et la colonisation. Les auteurs ont compare chez quatre populations exploitees a differentes periodes dans le passe, la production sporophyte des gametophytes a differents niveaux d'endogamie (autofecondation intragametophyte, autofecondation inter-gametophyte et croisement eloigne) a l'aide de croisements en laboratoire. A travers tous les traitements, 9.8% des gametophytes seulement formaient des sporophytes (N = 400 gametophytes). Aucun niveau d'endogamie, ni le temps ecoule depuis la perturbation n'affectait la production de sporophytes. La capacite d'autofecondation ne differait pas d'une population a l'autre, exploitees a des periodes differentes; il n'y avait pas d'interaction entre le niveau d'endogamie et le temps ecoule depuis la perturbation. Le faible succes reproducteur de D. punctilobula, peu importe le niveau d'endogamie ou le temps ecoule depuis la perturbation, suggere que l'etablissement et l'expansion de la population par la reproduction sexuee peut etre relativement rare chez cette espece clonale. [Traduit par la Redaction] Mots-cles : depression d'endogamie, espece envahissante, systemes de croisement, assurance reproductive, auto-fertilisation., Introduction Self-fertilization should facilitate plant invasions by providing reproductive assurance in new habitats, where mates or pollinators may be scarce (Darwin 1876; Baker 1955). In fact, introduced species often have [...]

Gynodioecy frequently results from the interplay of mitochondrial cytoplasmic male sterility (CMS) and nuclear fertility-restoration genes. Models suggest that maintaining cytonuclear gynodioecy requires that restorer genes incur a cost to fitness because otherwise they would increase toward fixation. Direct tests of costs of restorer alleles require knowledge of the underlying genetics of sex determination. We use a well characterized CMS system in Brassica napus L. to measure aspects of fitness in four lineages that vary in whether they carry the pol CMS gene or male-fertile cytoplasm (cam), and whether they carry the Rfp restorer of pol or Rfn restorer of the nap CMS gene. As expected, plants with pol CMS and only the Rfn restorer experienced reduced flower size, stamen length, and pollen counts. Plants with pol and the Rfp restorer showed incomplete restoration with shorter stamens than both lines with cam cytoplasm and reduced pollen counts compared with plants with cam cytoplasm and the Rfp restorer. Among plants with cam cytoplasm, pollen counts were higher for those with the Rfp than Rfn restorer, indicating a greater cost of restoration associated with Rfn. These results demonstrate that costs of restoration differ for the Rfn and Rfp alleles in B. napus. Key words: Brassica napus, CMS, cost of restoration, cytoplasmic male sterility, gynodioecy. La gynodrecie resulte frequemment de l'influence reciproque des genes mitochondriaux controlant la sterilite male cytoplasmique (CMS) et des genes nucleaires qui restaurent la fertilite. Des modeles suggerent que le maintien de la gynodrecie cyto-nucleaire necessite que les genes de restauration assument un cout vers l'aptitude phenotypique car sinon ils augmenteraient vers la fixation. Des tests directs des couts des alleles de restauration necessitent que l'on connaisse la genetique qui sous-tend la determination sexuelle. Les auteurs ont utilise un systeme de CMS bien connu chez Brassica napus L. afin de mesurer les aspects de l'aptitude phenotypique chez quatre lignages qui varient sur le fait qu'ils possedent gene de CMS pol ou un cytoplasme male-fertile (cam), et qu'ils possedent Rfp, le restaurateur de pol, ou Rfn, le restaurateur du gene de CMS nap. Comme prevu, les plants possedant pol et le restaurateur Rfn seulement produisaient des fleurs dont la taille, les etamines et le decompte en pollen etaient reduits. Les plants possedant le CMS pol et le restaurateur Rfp presentaient un retablissement incomplet avec des etamines plus courtes que celles des deux lignages possedant un cytoplasme cam, et un decompte en pollen reduit comparativement aux plants possedant un cytoplasme cam et le restaurateur Rfp. Parmi les plants possedant un cytoplasme cam, les decomptes en pollen etaient plus eleves que ceux qui possedaient le restaurateur Rfp plutot que Rfn, indiquant qu'un cout de restauration superieur est associe a Rfn. Ces resultats demontrent que les couts de restauration different entre les alleles RJh et Rfp chez B. napus. [Traduit par la Redaction] Mots-cles: Brassica napus, CMS, cout de restauration, sterilite male cytoplasmique, gynodrecie., Introduction Gynodioecy, in which populations contain both hermaphrodites and females, is the second most common angiosperm breeding system after hermaphroditism (Richards 1997; Sakai and Weller 1999). As implied by the [...]

In plant populations, limited seed dispersal may generate the aggregation of related individuals, which is referred to as spatial genetic structure (SGS). If short-distance pollination frequently occurs in populations with SGS, it may lead to frequent mating between related individuals (biparental inbreeding). In this study, we examined patterns of pollen dispersal and inbreeding under such conditions in a population of the wind-pollinated tree species Fagus crenata Blume using microsatellite analyses of adult trees and dispersed seeds. The population showed weak but significant SGS and the pollen dispersal in the population involved a combination of distance-dependent (largely short-range) dispersion at the local scale and long-distance transport. Although SGS and distance-dependent pollination co-occurred, individual inbreeding coefficients for both adults and seeds were almost zero, suggesting that mating generating sound seeds was genetically random with little or no inbreeding, probably because of the weak SGS, long-distance pollen dispersal, and postpollination mechanisms including self-incompatibility and inbreeding depression. The production of sound seeds through genetically random mating may be important for maintaining F. crenata populations because the resulting seedlings may be less affected by inbreeding depression than those resulting from the mating of related individuals. Key words: dispersal kernel, Fagus crenata, inbreeding coefficient, outcrossing rate, paternity analysis, wind pollination. Resume: Dans les populations vegetales, la dispersion limitee des graines peut generer une agregation des individus apparentes, phenomene que l'on appelle structure spatiale genetique (SSG). Si la pollinisation sur de courtes distances survient frequemment dans les populations avec SSG, ceci peut mener a un croisement frequent entre des individus apparentes (endogamie biparentale). Dans cette etude, les auteurs ont examine les patrons de dispersion du pollen et l'endogamie sous de telles conditions chez une population de Fagus crenata Blume, une espece d'arbres a pollinisation anemophile, a l'aide d'analyses de microsatellites des arbres adultes et des graines dispersees. La population presentait une SSG faible mais significative, et la dispersion du pollen dans la population impliquait la combinaison d'une dispersion en fonction de la distance (principalement de courte distance) a l'echelle locale et d'un transport de longue distance. Meme si la SSG et la pollinisation en fonction de la distance survenaient conjointement, les coefficients individuels d'endogamie des adultes et des graines etaient presque de zero, suggerant que le croisement generant des graines saines etait genetiquement aleatoire avec peu ou pas d'endogamie, probablement a cause de la faible SSG, de la dispersion du pollen sur une longue distance et des mecanismes post-pollinisation incluant l'auto-incompatibilite et la depression endogamique. La production de graines saines au moyen du croisement genetiquement aleatoire peut etre importante pour maintenir les populations de F. crenata car les semis resultants peuvent etre moins affectes par la depression endogamique que ceux qui resultent du croisement d'individus apparentes. [Traduit par la Redaction] Mots-cles : dispersion des grains, Fagus crenata, coefficient d'endogamie, taux de croisement eloigne, analyse de paternite, pollinisation anemophile., Introduction Gene dispersal via seeds and pollen strongly influences the genetic diversity and structure of plant populations. Genetic differentiation among populations is reduced by gene dispersal (i.e., gene flow) even [...]

Environmental stress in plants impacts many biological processes, including male gametogenesis, and affects several cytological mechanisms that are strongly interrelated. To understand the likely impact of rising temperature on reproductive fitness in the climate change regime, a study of tapetal mitosis and its accompanying meiosis over seasons was made to elucidate the influence of temperature change on the cytological events occurring during microsporogenesis. For this we used two species of an environmentally sensitive plant system, i.e., genus Cymbopogon Sprengel (Poaceae), namely Cymbopogon nardus (L.) Rendle var. confertiflorus (Steud.) Bor (2n = 20) and Cymbopogon jwaruncusha (Jones) Schult. (2n = 20). Both species flower profusely during extreme summer (48°C) and mild winter (15°C) but support low and high seed fertility, respectively, in the two seasons. We have shown that tapetal mitotic patterns over seasons entail differential behavior for tapetal mitosis. During the process of tapetum development there are episodes of endomitosis that form either (i) an endopolyploid genomically imbalanced uninucleate and multinucleate tapetum, and (or) (ii) an acytokinetic multinucleate genomically balanced tapetum, with the progression of meiosis in the accompanying sporogenous tissue. The relative frequency of occurrence of the two types of tapetum mitosis patterns is significantly different in the two seasons, and it is found to be correlated with the temperature conditions. Whereas, the former (genomically imbalanced tapetum) are prevalent during the hot summer, the latter (genomically balanced tapetum) are frequent under optimal conditions. Such a differential behaviour in tapetal mitosis vis-a-vis temperature change is also correspondingly accompanied by substantial disturbances or regularity in meiotic anaphase disjunction. Both species show similar patterns. The study underpins that tapetal mitotic behaviour per se could be a reasonable indicator to elucidate the effect of climate change on reproductive fitness. Key words: tapetum mitosis, tapetum division pattern, tapetum and meiosis, Cymbopogon, aromatic grass. Les stress environnementaux chez les plantes affectent plusieurs processus biologiques dont la gametogenese male et touchent plusieurs mecanismes cytologiques qui sont etroitement relies. Afin de comprendre l'impact vraisemblable des temperatures croissantes sur le succes reproductif dans le contexte des changements climatiques, les auteurs ont etudie la meiose dans le tapetum et la meiose qui l'accompagne au cours de plusieurs saisons afin de determiner l'influence des changements de temperature sur les evenements cytologiques survenant au cours de la microsporogenese. Pour ce faire, les auteurs ont employe deux especes composant un systeme vegetal sensible aux changements environnementaux, soit le genre Cymbopogon Sprengel (Poaceae) et particulierement le Cymbopogon nardus (L.) Rendle var. confertiflorus (Steud.) Bor (2n = 20) et le Cymbopogon jwaruncusha (Jones) Schult. (2n = 20). Ces deux especes fleurissent de maniere prolifique tant durant des canicules estivales (48°C) que des froids hivernaux moderes (15°C), mais cela se traduit respectivement par une fecondite faible et elevee au cours des deux saisons. Les auteurs montrent que les mitoses au sein du tapetum se deroulent de maniere differentielle au cours des saisons. Durant le developpement du tapetum, des episodes d'endomitose surviennent pour produire : (i) un tapetum endopolyploide uninuclee/multinuclee presentant un desequilibre genomique ou (ii) une mitose acytocinetique menant a un tapetum multinuclee mais equilibre en ce qui a trait a son genome et la poursuite de la meiose dans les tissus sporogenes voisins. La frequence relative des deux deroulements de la mitose differait significativement selon la saison et etait correlee avec la temperature. Tandis que le tapetum presentant un desequilibre genomique etait predominant durant les conditions estivales chaudes, le tapetum balance etait plus frequent sous des conditions optimales. Une telle difference de comportement dans la mitose au sein du tapetum en fonction de la temperature est egalement accompagnee de perturbations importantes ou de regularite de la disjonction lors de l'anaphase meiotique. Les deux especes presentent des changements similaires. Cette etude illustre que le comportement mitotique au sein du tapetum serait en soi un indicateur raisonnable pour determiner l'effet des changements climatiques sur la reproduction. [Traduit par la Redaction] Mots-cles : mitose au sein de tapetum, mode de division dans le tapetum, tapetum et meiose, Cymbopogon, graminee aromatique., Introduction The genus Cymbopogon Sprengel comprises a species complex of aromatic grasses that is a source of valuable essential oil used in perfumery and aromatherapy (Lavania 2000; Lavania et al. [...]

Natural regeneration-based silviculture has been increasingly regarded as a reliable option in sustainable forest management. However, successful natural regeneration is not always easy to achieve. Recently, new concerns have arisen because of changing future climate. To date, regeneration models have proved helpful in decision-making concerning natural regeneration. The implementation of such models into optimization routines is a promising approach in providing forest managers with accurate tools for forest planning. In the present study, we present a stochastic multistage regeneration model for Pinus pinea L. managed woodlands in Central Spain, where regeneration has been historically unsuccessful. The model is able to quantify recruitment under different silviculture alternatives and varying climatic scenarios, with further application to optimize management scheduling. The regeneration process in the species showed high between-year variation, with all subprocesses (seed production, dispersal, germination, predation, and seedling survival) having the potential to become bottlenecks. However, model simulations demonstrate that current intensive management is responsible for regeneration failure in the long term. Specifically, stand densities at rotation age are too low to guarantee adequate dispersal, the optimal density of seed-producing trees being around 150 stems-ha-1. In addition, rotation length needs to be extended up to 120 years to benefit from the higher seed production of older trees. Stochastic optimization confirms these results. Regeneration does not appear to worsen under climate change conditions; the species exhibiting resilience worthy of broader consideration in Mediterranean silviculture. Key words: multistage models, transition probability, stochastic spatial optimization, stochastic simulation, climatic change. Resume: La sylviculture fondee sur la regeneration naturelle est de plus en plus consideree comme une option fiable pour l'amenagement forestier durable. Cependant, il n'est pas toujours facile de reussir a etablir une regeneration naturelle. Recemment, de nouvelles preoccupations ont ete soulevees en raison des futurs changements climatiques. Jusqu'a present, les modeles de regeneration se sont averes utiles pour la prise de decision concernant la regeneration naturelle. L'application de ces modeles dans des routines d'optimisation est une approche prometteuse pour fournir aux amenagistes forestiers des outils precis pour la planification forestiere. Dans la presente etude, nous presentons un modele de regeneration stochastique multistage pour les forets amenagees de Pinus pinea L. du centre de l'Espagne ou la regeneration a historiquement ete infructueuse. Le modele est en mesure de quantifier le recrutement en fonction de differentes methodes sylvicoles et de divers scenarios climatiques, en plus d'optimiser le calendrier d'amenagement. Le processus de regeneration de cette espece a montre une forte variation interannuelle et tous les sous-processus (production, dispersion, germination et predation des graines ainsi que survie des semis) peuvent devenir des goulots d'etranglement. Cependant, les simulations du modele montrent que l'amenagement intensif presentement applique est responsable de l'echec de la regeneration a long terme. Specifiquement, la densite des peuplements a l'[caret.a]ge d'exploitabilite est trop faible pour garantir une dispersion adequate, la densite optimale des arbres semenciers etant d'environ 150 tiges h[a.sup.-1]. De plus, la duree de la rotation doit etre allongee jusqu'a 120 ans pour tirer profit de la plus forte production de semences des plus vieux arbres. L'optimisation stochastique confirme ces resultats. L'etablissement de la regeneration ne semble pas devenir plus difficile sous des conditions de changement climatique; l'espece fait preuve d'une resilience qui merite d'etre mieux consideree par la sylviculture mediterraneenne. [Traduit par la Redaction] Mots-cles: modeles multistages, probabilite de transition, optimisation spatiale stochastique, simulation stochastique, changements climatiques., Introduction One of the main aims of sustainable forest management is to guarantee forest persistence over time (Nyland 2002). This general objective implies that managed stands need to be successfully [...]

Patterns of jack pine (Pinus banksiana Lambert) pollen cone production are of interest because they may help explain jack pine budworm (Choristoneura pinus pinus Freeman) outbreak patterns. We used generalized linear mixed models to analyze pollen cone production in 180 permanent plots in Ontario, Canada between 1992 and 2008. Pollen cone production increased with stand age, and large trees in sparsely-populated stands produced more pollen cones. Defoliation decreased the propensity of trees to produce pollen cones for at least two years. We also identified important patterns that are not explained by defoliation and stand characteristics. Pollen cone production is spatially synchronized among years, trees in central Ontario produced more pollen cones than trees in northwestern Ontario, and background cone production increased over time in the central region but not in more northwestern plots. Synchronized reproduction is common among tree species, but has not previously been noted for jack pine pollen cones. Increasing cone production in central Ontario may be evidence of changing forest and (or) climatic conditions and deserves further investigation. Our model can be used to quantitatively predict pollen cone production and assess the risk of jack pine budworm defoliation. Key words: Choristoneura pinus pinus, Pinus banksiana, population dynamics, spatial synchrony, insect plant interactions. Resume: Les profils de production de cones males chez le pin gris (Pinus banksiana Lambert) presentent un interet parce qu'ils pourraient contribuer a expliquer le comportement des epidemies de tordeuse du pin gris (Choristoneura pinus pinus Freeman). Nous avons utilise des modeles lineaires mixtes generalises pour analyser la production de cones males dans 180 placettes permanentes en Ontario, au Canada, entre 1992 et 2008. La production de cones males augmentait avec l'age du peuplement et les gros arbres dans les peuplements clairsemes produisaient plus de cones males. La defoliation reduisait la propension des arbres a produire des cones males pendant au moins deux ans. Nous avons aussi identifie des profils importants qui ne sont pas expliques par la defoliation ni par les caracteristiques du peuplement. La production de cones males est spatialement synchronisee d'une annee a l'autre: les arbres produisaient plus de cones males dans le centre que dans le nord-ouest de l'Ontario, et la production historique de cones males a augmente avec le temps dans la region centrale mais pas dans les placettes les plus eloignees vers le nord-ouest. La reproduction synchrone est courante parmi les especes d'arbre mais n'avait pas jusqu'ici ete observee chez les cones males du pin gris. La production accrue de cones males dans le centre de l'Ontario pourrait etre un indice que les conditions climatiques et la foret changent et merite d'etre davantage etudiee. Notre modele peut etre utilise pour predire de facon qualitative la production de cones males et evaluer le risque de defoliation par la tordeuse du pin gris. [Traduit par la Redaction] Mots-cles: Choristoneura pinus, Pinus banksiana, dynamique des populations, synchronisme spatial, interactions entre les plantes et les insects., Introduction Many animal populations undergo large, spatially synchronized changes in abundance over time, and determining the causes of these patterns is a central topic in population ecology (Bjornstad and Grenfell [...]

Small fragmented populations often exhibit reduced plant-pollinator interactions and scarce outcrossing opportunities. In this context, mixed-mating systems can be advantageous since selfing can provide reproductive assurance, but they may also carry relevant costs such as those involved in inbreeding depression. This study examines the advantages and costs of selfing in Narcissus serotinus L., a mixed-mating geophyte that currently occurs in several fragmented populations in Portugal, that resulted from the construction of the largest European dam. Observation of pollinators revealed that cross-pollination is less frequent in small than in large populations. Manual self-pollinations significantly increased fruit and seed set in small-size populations, also suggesting limited insect pollination. The existence of selfing may provide reproductive assurance in small-size populations of N. serotinus where outcrossing pollination is reduced. Although floral biology and experimental pollinations showed that N. serotinus is capable of autonomous selfing, four of the six fitness traits studied showed significant inbreeding depression in all populations. The high levels of inbreeding depression found in N. serotinus suggest that the initial reproductive assurance advantage of selfing may be counterbalanced by lower survival of the resulting individuals and a decrease in the evolutionary potential of the populations. Key words: fragmentation, human disturbance, inbreeding depression, mixed-mating system, selfing. Les petites populations fragmentees presentent souvent des interactions plante-pollinisateur reduites et des opportunites de croisement eloigne rares. Dans ce contexte, les systemes de croisement mixtes peuvent etre avantageux car l'endogamie peut fournir une assurance reproductive, mais elle peut aussi comporter des couts relies tels ceux impliques dans la depression de consanguinite. Cette etude a examine les avantages et les couts de l'endogamie chez Narcissus serotinus L., un geophyte a systeme mixte de reproduction qui apparait actuellement chez plusieurs populations fragmentees au Portugal, a la suite de la construction du plus grand barrage en Europe. L'observation des pollinisateurs a revele que la pollinisation croisee est moins frequente chez les petites populations comparativement aux plus grandes. L'autopollinisation manuelle augmentait significativement la nouaison et lagrenaison dans les populations de petite taille, suggerant aussi une pollinisation par les insectes reduite. L'existence d'endogamie peut fournir une assurance reproductive dans les populations de petite taille de N. serotinus ou la pollinisation par croisement eloigne est reduite. Meme si la biologie florale et les pollinisations experimentales ont montre que N. serotinus est capable d'endogamie, quatre de six traits de fitness etudies ont montre une depression de consanguinite significative chez toutes les populations. Les hauts niveaux de depression de consanguinite trouves chez N. serotinus suggerent que l'avantage initial de l'assurance reproductive de l'endogamie peut etre contrebalance par une survie plus faible des individus qui en resultent et une diminution du potentiel evolutionnaire des populations. [Traduit par la Redaction] Mots-cles: fragmentation, perturbation anthropique, depression de consanguinite, systeme de reproduction mixte, endogamie., Introduction A general effect of human activities is that natural habitats are frequently lost or changed (Allendorf and Luikart 2007). These human-induced changes may affect persistence and survival of species, [...]

Plant species diversity in Eurasian wetlands and grasslands depends not only on productivity but also on the relative availability of nutrients, particularly of nitrogen and phosphorus (1-4). Here we show that the impacts of nitrogen:phosphorus stoichiometry on plant species richness can be explained by selected plant life-history traits, notably by plant investments in growth versus reproduction. In 599 Eurasian sites with herbaceous vegetation we examined the relationship between the local nutrient conditions and community-mean life-history traits. We found that compared with plants in nitrogen-limited communities, plants in phosphorus-limited communities invest little in sexual reproduction (for example, less investment in seed, shorter flowering period, longer lifespan) and have conservative leaf economy traits (that is, a low specific leaf area and a high leaf dry-matter content). Endangered species were more frequent in phosphorus-limited ecosystems and they too invested little in sexual reproduction. The results provide new insight into how plant adaptations to nutrient conditions can drive the distribution of plant species in natural ecosystems and can account for the vulnerability of endangered species., Species diversity is influenced both by overall nutrient availability and by nutrient stoichiometry--that is, how the ratio of available nutrients relates to their consumers' requirements (5). In terrestrial plant communities [...]

The present paper reports our observations on the mode of reproduction in Taraxacumudum (sect. Palustria), a very rare species in Poland, known only from a single locality. Based on the analysis of the developmental processes in the ovules, it can be concluded that this bog dandelion is an obligate and autonomous apomict. Its reproduction involves (i) restitutional diplospory, also known as Taraxacum type; (ii) parthenogenesis; and (iii) autonomous endosperm formation. Moreover, observations on the anatomy of ovules confirmed the occurrence of a special storage tissue around the embryo sac, which is considered to be an additional source of nutrition for the embryo. An examination of the anthers showed that, in spite of highly disturbed meiosis, apomictic T. udum produces pollen but pollen grains are heterogeneous in size and stainable using an acetocarmine test. Key words: Taraxacum, apomixis, diplospory, parthenogenesis, autonomous endosperm, microsporogenesis, pollen grains. Resume : Les auteurs presentent des observations sur le mode de reproduction du Taraxacum udum (sect. Palustria), une espece endemique de la Pologne, dont une seule localite est connue. Sur la base de l'analyse des processus de developpement dans les ovules, on peut conclure que ce pissenlit de tourbieres constitue une espece apomictique obligatoire et autonome. Sa reproduction implique (i) une diplosporie restitutionnelle, egalement connue comme de type Taraxacum,(ii) la parthenogenese, et (iii)la formation autonome de l'endosperme. De plus, des observations de l'anatomie des ovules confirment la presence de tissus speciaux d'emmagasinage autour du sac embryonnaire, consideres comme source additionnelle de nutriments pour l'embryon. L'examen des antheres montre que, en depit d'une meiose fortement perturbee, le T. udum apomictique produit du pollen, mais les grains de pollen sont de dimensions heterogenes et colorables a l'acetocarmin. [Traduit par la Redaction] Mots-cles: Taraxacum, apomixie, diplosporie, parthenogenese, endosperme autonome, microsporogenese, grains de pollen., Introduction Members of the genus Taraxacum Wigg. (Asteraceae-Cichorioideae) are some of the most common plants spread throughout the temperate zone of both the northern and southern hemisphere. The western Himalayan [...]

Simple, operational tools are required for forest managers to quantify the effects of soil fertility on tree growth and ecosystem sustainability leading to precise, sustainable forest management. The simplified process-based 3-PG model (Landsberg, J.J., and Waring, R.H., For. Ecol. Manage. 95: 209-228, 1997) provides a useful framework for operational prediction of forest growth. However, no simple objective method for relating the effects of available soil nutrients to the model fertility parameter fertility rating (FR) is yet available. The present study aimed to compare several general modeling approaches for the estimation of FR values from soil relative nutrient contents (RNCs) to maximum nonlimiting values, measured in the whole soil profile, at continuous inventory plots of Eucalyptus globulus Labill. in several locations under different parent materials in northwestern Spain. The modeling approaches tested provided good predictions of FR values from RNCs. In particular, using the minimum value of the most significant RNCs showed considerable potential for modeling FR values and plantation growth responses to them. This modeling approach showed promise to be further tested as a generally applicable strategy for estimating the effect of soil nutrients on forest plantations growth. Resume: Des outils simples et operationnels sont necessaires aux amenagistes forestiers pour quantifier les effets de la fertilite du sol sur la croissance des arbres et la durabilite des ecosystemes menant a un amenagement forestier precis et soutenu. Le modele 3-PG simplifie, fonde sur des processus ecophysiologiques (Landsberg, J.J., et Waring, R.H., For. Ecol. Manage. 95: 209-228, 1997), offre un cadre utile de prevision operationnelle de la croissance forestiere. Cependant, aucune methode simple et objective n'est encore disponible pour faire le lien entre les effets de la disponibilite des nutriments du sol et le parametre d'indice de fertilite (IF) du modele. La presente etude vise a comparer plusieurs approches generales de modelisation pour estimer des valeurs d'IF a partir du contenu relatif en nutriments du sol (CRN) pouvant atteindre des valeurs maximales non limitatives. Le CRN a ete mesure dans le profil complet du sol de parcelles d'inventaire continu d'Eucalyptus globulus Labill. etablies a plusieurs endroits sur differents materiaux parentaux dans le nord-ouest de l'Espagne. Les approches de modelisation testees ont produit de bonnes previsions des valeurs d'IF a partir des CRN. En particulier, l'utilisation de la valeur minimale des CRN les plus significatifs a montre un potentiel considerable pour modeliser les valeurs d'IF de meme que son effet sur la reaction de croissance des plantations. Cette approche de modelisation prometteuse merite d'etre davantage testee comme strategie d'application generale pour estimer l'effet des nutriments du sol sur la croissance des plantations forestieres. [Traduit par la Redaction], Introduction In spite of the well-documented relevance of soil nutrition on tree growth (e.g., Merino et al. 2003, Laclau et al. 2010), there is a scarcity of practical modeling tools [...]

Key biological processes such as the timing and synchrony of reproduction, are sensitive to fluctuations in the environment, as well as alterations in the physiology and behaviour of individuals and the ecology of populations. The main aim of this study was to identify patterns in reproductive timing and relationships with prevailing environmental conditions, for the major habitat-forming alga in temperate Australia, Ecklonia radiata (C. Agardh) J. Agardh. We observed strong synchronous patterns of zoospore production across spatial scales from hundreds of metres to tens of kilometres, with populations of E. radiata reproducing from mid-summer to the end of autumn. High zoospore densities were positively related to sea temperature and E. radiata released zoospores in temperatures well above previously documented thermal tolerance limits for other Laminariales. Reproductive timing was also negatively related to seasonal increase in wave exposure. We conclude that E. radiata undergoes synchronous reproduction which can be linked to its annual growth cycle and natural environmental fluctuations, to promote growth and survival of recruits., Introduction Reproductive synchrony is an important evolutionary adaptation that is widely documented in both marine and terrestrial organisms (Ims 1990). Simultaneous reproduction within a population allows for the release of [...]

Triuris brevistylis Donn. Sm. (Triuridaceae: Pandanales), a mycoheterotrophic monocotyledon with populations in Mexico and Guatemala, is closely related to Lacandonia schismatica E. Martinez et C. H. Ramos, a triurid species displaying a peculiar 'inside-out' arrangement in its reproductive axes. Triuris brevistylis is a polygamodioecious species in which four types of bisexual ramets-genets coexist besides regular (i.e., unisexual) male and female flowers. Here, we characterize the embryology of three of the following different types of reproductive axes in T. brevistylis: male and female flowers and a bisexual floral type in which stamens develop at the base of the receptacle of an otherwise femalelooking flower. Through this embryological characterization, we have detected that cleistogamy, a mechanism previously considered exclusive to L. schismatica, occurs in the bisexual flowers. Besides serving as characters for the systematics of Triuridaceae and Pandanales, our data establish that morphogenetic and reproductive patterns in T. brevistylis are more complex than in L. schismatica. Therefore, we claim that our results contribute to a refined assessment of the controversy regarding morphological interpretation of reproductive axes in triurids. Key words: embryology, cleistogamy, Lacandonia, polygamodioecy, Triuridaceae, Triuris. Le Triuris brevistylis Donn. Sm. (Triuridaceae : Pandanales), une espece mycoheterotrophe avec des populations au Mexique et au Guatemala, est etroitement reliee au Lacandonia schismatica E. Martinez et C. H. Ramos, une espece de triuride montrant un arrangement particulier 'interne-externe' de ses axes reproductifs. Le T. brevistylis est une espece polygamodio'ique chez laquelle coexistent quatre types de ramettes- genets bisexues, en plus des fleurs males et femelles regulieres. Les auteurs ont caracterise l'embryologie de trois types differents d'axes reproductifs chez le T. brevistylis : fleurs males et femelles, et un type bisexue de fleur dans lequel les etamines se developpement a la base du receptacle d'une autre fleur d'allure femelle. Par cette caracterisation embryologique, les auteurs ont pu s'apercevoir que la cleistogamie, un mecanisme jusqu'ici considere comme exclusif au L. schismatica, survient chez les fleurs bisexuees. En plus de servir comme caracteres pour la systematique des Triuridaceae et des Pandanales, ces donnees etablissent que les patrons morphogenetiques et reproductifs du T. brevistylis sont plus complexes que chez le L. schismatica. Consequemment, les auteurs avancent que leurs resultats contribuent a une evaluation plus precise de la controverse concernant l'interpretation morphologique des axes de reproduction chez les triurides. Mots-cles : embryologie, cleistogamie, Lacandonia, polygamodioecie, Triuridaceae, Triuris. [Traduit par la Redaction], Introduction The monocotyledon family Triuridaceae Gardner is comprised of 11 extant genera and approximately 50 species of small, inconspicuous mycoheterotrophic plants, distributed mostly throughout the tropical and subtropical regions of [...]

The growth of pollen tubes is one of the most characteristic events in angiosperm reproduction. This article describes an activity for visualizing the journey and guidance of pollen tubes in the reproductive structures of a flowering plant. The activity uses a semi-in vivo system with rapid-cycling Brassica rapa, also known as Fast Plants. Isolated ovules were used to attract pollen tubes that were triggered to grow through explants of female flower parts. The activity provides insight into the in vivo situation of plant reproduction, appealing visual results, and the development of science process skills. Key Words: Fast Plants; Brassica rapa; pollen germination; guidance; flower anatomy., Sexual reproduction is one of the most important features in the life cycle of higher plants. In contrast to animals, plant fertilization is based on the interplay between multicellular haploid [...]

Sexual reproduction in non-vascular plants requires unicellular free-motile sperm to travel from male to female reproductive structures across the terrestrial landscape (1). Recent data suggest that microarthropods can disperse sperm [...]

Pollen-ovule (P/O) ratios were determined for five Vaccinium species (Ericaceae) native to eastern Canada (Nova Scotia: V angustifolium, V. boreale, V. caespitosum, V. corymbosum, V. uliginosum), one in western Canada (Saskatchewan: V myrtilloides), and one (V vitis-idaea) from both provinces. Pollen, released at maturity as tetrads, was converted to total pollen grains per flower to yield P/O ratios ranging from 238 (V caespitosum) to 2008 (V vitis-idaea), but 736 for the latter in Saskatchewan. These P/O ratios are indicative of facultative autogamy to facultative xenogamy. Additionally, the structure of mature stamens and pollen tetrads was studied in V myrtilloides and V vitis-idaea. Each anther was functionally bilocular; had a single-cell thickness (i.e., epidermis) with regularly occurring papillae; lacked an endothecium; and possessed two distal, hollow tubules each terminating in a pore. Overall pollen grain viability was 76%-97% (V myrtilloides) and 51%93% (V vitis-idaea), with about 20% of tetrads having only 1-3 grains viable, and 12% and 27% of tetrads entirely nonviable in V myrtilloides and V vitis-idaea, respectively. Pollen tetrads occasionally were connected by a sticky substance resembling pollenkitt, but viscin threads were absent. One instance of precocious (in situ) germination of tetrads was recorded within anthers of V myrtilloides. Key words: pollen-ovule ratios, pollen tetrads, pollen viability, poricidal anther, stamen structure, Vaccinium. Les auteurs ont determine les ratios pollen-ovule (P/O) chez 5 especes de Vaccinium (Ericaceae) indigenes de l'Est canadien (Nouvelle-Ecosse: V. angustifolium, V. boreale, V. caespitosum, V. corymbosum, V. uliginosum), une de l'Ouest canadien (Saskatchewan: V. myrtilloides)etle(V. vitis-idaea), provenant des deux provinces. Ils ont converti le pollen libere a maturite en tetrades, en terme de total de grains de pollen par fleur et ainsi obtenir des ratios P/O allant de 238 (V caespitosum) a 2,008 (V vitis-idaea), mais seulement 736 pour cette derniere en Saskatchewan. Ces ratios sont l'indication d'une autogamie facultative a une xenogamie. Ils ont de plus etudie la structure des etamines matures et des tetrades de pollen chez le V myrtilloides et le V vitis-idaea. Chaque anthere est fonctionnellement biloculaire, montre une seule couche de cellule (i. e. epiderme), avec la presence reguliere de papilles, sans endotheque et avec deux tubules distaux vides se terminant par un pore. Dans l'ensemble la viabilite du pollen etait de 76-97% (V myrtilloides) et 51-93% (V vitis-idaea), environ 20% des tetrades possedant seulement 1-3 grains viables, et 12% et 27 % des tetrades entierement non viables, chez les V myrtilloides et V vitis-idaea respectivement. Les tetrades de pollen sont occasionnellement reliees par une substance collante ressemblant a un pollenkitt, mais sans la presence de filaments de viscine. On a observe un cas de germination precoce de tetrades (in situ) dans les antheres du V myrtilloides Mots-cles : ratios pollen-ovule, tetrades de pollen, viabilite du pollen, anthere poricidique, structure des etamines, Vaccinium. [Traduit par la Redaction], Introduction Vaccinium L. is a well recognized and widely distributed genus in the family Ericaceae. Although primarily known for its edible fruit-yielding temperate species such as blueberry and cranberry, the [...]

Humulus lupulus L. is a dioecious perennial plant, cultivated for its female inflorescences. Spontaneously arising monoecious hop plants, carrying male and female flower types on a specific plant, occasionally occur in the progeny of certain hop crosses. We assessed the ploidy of 58 monoecious plants, progenies of various crosses of diploid parents, to provide additional data on hop monoeciousy. Flow cytometric analysis revealed that a high percentage (41.4%) were triploid. An inheritance analysis of parental alleles using six codominant SSR markers demonstrated a primarily paternal origin (84.2%) of unreduced gametes as the cause of triploidy in monoecious plants. All triploids had predominantly male flowers with a few female cones; this phenotype was found only within this ploidy group. All other monoecious plants were diploid, except for one genotype with the highest nuclear DNA content, which showed an aneuploidic number of chromosomes (21). Male hops showed the lowest nuclear DNA amount, as measured by DAPI and propidium iodide fluorochromes. The estimated AT frequency placed hop among species with a high AT content, which was slightly higher in male than in female plants (63.0% vs. 62.5%). The results are discussed in relation to the occurance of ploidy and sex expression in monoecious hop. Key words: hop, flow cytometry, nuclear DNA content, SSR markers, unreduced gametes. On cultive l'Humulus lupulus L., une plante dioique perenne, pour ses inflorescences femelles. Des plants de houblon monoiques se forment spontanement, portant les types de fleurs males et femelles sur une plante specifique, apparaissant occasionnellement dans la progeniture de certains croisements de houblon. Les auteurs ont evalue la ploidie de 58 plantes monoiques, provenant de divers croisements entre parents diploides, afin d obtenir des donnees additionnelles sur la monoecie du houblon. L'analyse cytometrique en flux revele un fort pourcentage (41,4%) d'individus triploides. Une analyse d'heredite des alleles parentaux en utilisant six marqueurs SSR codominants demontre surtout une origine paternelle des gametes non reduits comme cause de la triploidie des plantes monoiques. Tous les triploides possedent surtout des fleurs males avec quelques cones femelles; on retrouve ce phenotype seulement dans ce groupe de ploidie. Toutes les autres plantes monoiques sont diploides, sauf pour un genotype possedant le contenu le plus important en ADN nucleique, indiquant un nombre aneuploidique de chromosomes (21). Les houblons males montrent la plus faible quantite d ADN nucleique, tel que mesure par la coloration DAPI et les fluorochromes de l'iodure de propidium. Les frequences AT estimees placent le houblon parmi les especes a contenu AT eleve legerement plus important chez les plants males que chez les femelles (63,0% vs. 62,5%). Les auteurs discutent les resultats en relation avec l'incidence de la ploidie et l'expression du sexe chez le houblon monoique. Mots-cles : houblon, cytometrie en flux, teneur en ADN nucleique, marqueurs SSR, gametes non reduits. [Traduit par la Redaction], Introduction Most flowering plants are hermaphroditic, with only about 6% of angiosperms being dioecious (Renner and Ricklefs 1995). Dioecious plants have evolved quite recently from ancestors with hermaphroditic flowers (Westergaard [...]

Recent work on the ecosystem service of biodiversity suggests that higher pollinator diversity could lower pollen limitation, but these two aspects of plant-pollinator communities have only rarely been causally connected. Here we present a review of studies that produced quantitative assessments of both pollinator diversity and evenness as well as pollen limitation of focal plant species. Although pollen limitation is expected to be lower when pollinator diversity is high, our analysis suggests this relationship is weak. The relationship may be obscured when features of the plant species (e.g., average level of specialization) are confounded with features of the plant communities (e.g., habitat). We encourage researchers investigating pollen limitation to consider including measures of diversity of the floral visitors, and their effectiveness. These data would permit a more powerful test of the relationships among these variables and improve our understanding of the critical elements of stable plant-pollinator networks. Key words: ecosystem services, pollination, pollen, insects, flowering plants, pollinator diversity. Un travail recent sur les services rendus aux ecosystemes par la biodiversite suggere qu'une plus grande diversite de pollinisateurs pourrait reduire la limitation par le pollen, mais on a rarement etabli la relation de cause a effet de ces deux aspects de la relation plantes-pollinisateurs communautes. Les auteurs presentent une revue des etudes ayant produit des evaluations quantitatives a la fois de la diversite des pollinisateurs et l'uniformite et de la limitation par le pollen d'especes vegetales determinees. Bien que l'on s'attende a ce que la limitation par le pollen soit plus faible en presence d' une forte diversite de pollinisateurs, les auteurs constatent que cette relation est faible. La relation est possiblement masquee lorsque les particularites de l'espece vegetale (p. ex., degre moyen de specialisation) se confondent avec les particularites des communautes vegetales (p. ex., habitat). On encourage les chercheurs sur la limitation par le pollen a considerer des mesures inclusives de la diversite des visiteurs floraux, et leur efficacite. Ces donnees fourniraient une evaluation plus forte des relations entre ces variables et amelioreraient notre comprehension des elements critiques des reseaux stables plante-pollinisateur. Mots-cles : services aux ecosystemes, pollinisation, pollen, insectes, plantes a fleurs, diversite des pollinisateurs. [Traduit par la Redaction], Introduction Pollen limitation (PL), the reduction in plant reproductive success as a result of inadequate quantity or quality of pollen deposition, is widespread among flowering plants. Previous reviews have calculated [...]