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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 selfing 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. [ABSTRACT FROM AUTHOR]

Abstract Background Plants in cliff habitats may evolve specific reproductive strategies to cope with harsh environments, and unraveling these reproductive characteristics can improve our understanding of survival strategies and lithophyte evolution. This understanding is especially important for efforts to protect rare and endemic plants. Here, we investigated the reproductive biology of Lonicera oblata, an endangered lithophytic shrub that is scattered in highly fragmented and isolated cliff habitats of the Taihang and Yan mountains in North China. Results Flowers of L. oblata are herkogamous and protandrous, characteristics that can prevent autogamy at the single-flower level, and insects are necessary for pollination. The outcrossing index, pollen/ovule ratio, and the results of hand pollination were measured and all revealed a mixed mating system for L. oblata, that combines cross-fertilization and partial self-fertilization. The floral traits of L. oblata of zygomorphic and brightly yellowish corolla, heavy fragrance, and rich nectar, suggest an entomophilous pollination system. Sweat bees were observed as the most effective pollinators but their visiting frequencies were not high. Pollen limitation may limit the reproductive success of L. oblata. Conclusions We determined the reproductive characteristics of L. oblata, a critically endangered species endemic to cliffs in North China, providing insight into its endangerment and suggesting conservation strategies. L. oblata has highly pollinator-dependent self-fertilization as part of a mixed mating system. Floral features such as low-flowering synchrony, asynchronous anthers dehiscence, and high duration of stigma receptivity, improve pollination efficiency in the case of low pollinator service. Our work provides reference information to understand the survival strategies and conservation of L. oblata and other lithophytes.

The transition from outcrossing to selfing is a common evolutionary trend in flowering plants, and floral traits change significantly with the evolution of selfing. Whether or not plant traits are subjected to selection remains an open question in species with mixed mating systems. We examined phenotypic selection in two populations of Halenia elliptica with different selfing rates. We found that the pollen–ovule ratio, seed size, plant height, spur length, and pollinator visitation rate in the population with the higher selfing rate were lower than those in the population with the lower selfing rate. Selfing provides reproductive assurance for populations when pollinator service is low, and the floral traits that are associated with selfing syndrome are evident in populations with a higher selfing rate but are subjected to weak selection in each of the two populations with different selfing rates. Directional selection for an early flowering time indicated that late blooming flowers could experience a risk of seed development in alpine environments, and for large plants, selection indicated that seed production could be limited by the available resources. The floral traits that are associated with pollinator attraction and specialization could be subjected to weak selection at the plant level as selfing evolves, and the selective pressures that are independent of pollinators might not change significantly; highlighting the selective biotic and abiotic pressures that shape the morphological traits of plant species and their independence from the mating system. [ABSTRACT FROM AUTHOR]

About one-fifth of angiosperms reproduce predominantly through self-fertilization, mediated by morphological and functional flower traits. Autonomous selfing is rare in Melastomataceae, a megadiverse family with most species featuring poricidal anthers and herkogamy. However, previous studies suggested that some Bertolonia spp. were capable of autonomous selfing. Here, we investigated the existence of autonomous selfing in the group and, considering its specialized floral morphology, the mechanisms involved in this process. We conducted studies on floral biology, pollination experiments and pollinator visitation rates for Bertolonia paranaensis (anthers with introrse pores) and Bertolonia mosenii (anthers with extrorse pores). The transient absence of herkogamy and the dynamics of the movements of the flower parts during post-anthesis events promoted delayed selfing in both species. In post-anthesis flowers, pollen grains germinate inside the anthers, the pollen tubes come out through the anther pores and then reach the stigma, penetrating the transmission tissue, and fertilize the ovules. Both species received visits from buzzing bees and have a mixed mating system, i.e. the capacity of cross-pollination and delayed selfing-pollination. We present the first description of an autonomous selfing mechanism for plants with poricidal anthers, for which we coin the name "pollen tube shower". Pollen tube shower promotes reproductive assurance to flowers that have not been pollinated and ensures reproductive success of individuals in the absence of pollinators. [ABSTRACT FROM AUTHOR]

Background: Plants in cliff habitats may evolve specific reproductive strategies to cope with harsh environments, and unraveling these reproductive characteristics can improve our understanding of survival strategies and lithophyte evolution. This understanding is especially important for efforts to protect rare and endemic plants. Here, we investigated the reproductive biology of Lonicera oblata, an endangered lithophytic shrub that is scattered in highly fragmented and isolated cliff habitats of the Taihang and Yan mountains in North China. Results: Flowers of L. oblata are herkogamous and protandrous, characteristics that can prevent autogamy at the single-flower level, and insects are necessary for pollination. The outcrossing index, pollen/ovule ratio, and the results of hand pollination were measured and all revealed a mixed mating system for L. oblata, that combines cross-fertilization and partial self-fertilization. The floral traits of L. oblata of zygomorphic and brightly yellowish corolla, heavy fragrance, and rich nectar, suggest an entomophilous pollination system. Sweat bees were observed as the most effective pollinators but their visiting frequencies were not high. Pollen limitation may limit the reproductive success of L. oblata. Conclusions: We determined the reproductive characteristics of L. oblata, a critically endangered species endemic to cliffs in North China, providing insight into its endangerment and suggesting conservation strategies. L. oblata has highly pollinator-dependent self-fertilization as part of a mixed mating system. Floral features such as low-flowering synchrony, asynchronous anthers dehiscence, and high duration of stigma receptivity, improve pollination efficiency in the case of low pollinator service. Our work provides reference information to understand the survival strategies and conservation of L. oblata and other lithophytes. [ABSTRACT FROM AUTHOR]

The transition from outcrossing to selfing is a common evolutionary trend in flowering plants, and floral traits change significantly with the evolution of selfing. Whether or not plant traits are subjected to selection remains an open question in species with mixed mating systems. We examined phenotypic selection in two populations of Halenia elliptica with different selfing rates. We found that the pollen–ovule ratio, seed size, plant height, spur length, and pollinator visitation rate in the population with the higher selfing rate were lower than those in the population with the lower selfing rate. Selfing provides reproductive assurance for populations when pollinator service is low, and the floral traits that are associated with selfing syndrome are evident in populations with a higher selfing rate but are subjected to weak selection in each of the two populations with different selfing rates. Directional selection for an early flowering time indicated that late blooming flowers could experience a risk of seed development in alpine environments, and for large plants, selection indicated that seed production could be limited by the available resources. The floral traits that are associated with pollinator attraction and specialization could be subjected to weak selection at the plant level as selfing evolves, and the selective pressures that are independent of pollinators might not change significantly; highlighting the selective biotic and abiotic pressures that shape the morphological traits of plant species and their independence from the mating system.

Abstract Hymenaea stigonocarpa is a neotropical tree that is economically important due to its high‐quality wood; however, because it has been exploited extensively, it is currently considered threatened. Microsatellite loci were used to investigate the pollen and seed dispersal, mating patterns, spatial genetic structure (SGS), genetic diversity, and inbreeding depression in H. stigonocarpa adults, juveniles, and open‐pollinated seeds, which were sampled from isolated trees in a pasture and trees within a forest fragment in the Brazilian savannah. We found that the species presented a mixed mating system, with population and individual variations in the outcrossing rate (0.53–1.0). The studied populations were not genetically isolated due to pollen and seed flow between the studied populations and between the populations and individuals located outside of the study area. Pollen and seed dispersal occurred over long distances (>8 km); however, the dispersal patterns were isolated by distance, with a high frequency of mating occurring between near‐neighbor trees and seeds dispersed near the parent trees. The correlated mating for individual seed trees was higher within than among fruits, indicating that fruits present a high proportion of full‐sibs. Genetic diversity and SGS were similar among the populations, but offspring showed evidence of inbreeding, mainly originating from mating among related trees, which suggests inbreeding depression between the seed and adult stages. Selfing resulted in a higher inbreeding depression than mating among relatives, as assessed through survival and height. As the populations are not genetically isolated, both are important targets for in situ conservation to maintain their genetic diversity; for ex situ conservation, seeds can be collected from at least 78 trees in both populations separated by at least 250 m.

Austropuccinia psidii is a rust fungus that has expanded its known geographic distribution and host range on Myrtaceae. Invasions by rust fungi are often caused by asexual urediniospores that give rise to populations with low genotypic diversity. Recently it was shown that basidiospores, the gametic spores of A. psidii, were able to infect species of Myrtaceae under controlled conditions. The present study tested the hypothesis that sexual reproduction occurs through infection of Myrtaceae by basidiospores of A. psidii in recently invasive populations from New Zealand and South Africa. We provided three lines of evidence to test this hypothesis: i) presence of a sexual stage, ii) high genotypic diversity within an invasive population, and iii) no genetic linkage between microsatellite markers in multilocus genotypes. Our results provide evidence that invasions of A. psidii are caused by both urediniospores that spread clonal genotypes, and teliospores that produce recombinant basidiospores, which infect Myrtaceae. We reject the hypothesis that field infections of A. psidii are only caused by asexual urediniospores, and support that sexual reproduction occurs in invasive populations and may accelerate adaptation to environmental change. [ABSTRACT FROM AUTHOR]

The increase in habitat fragmentation impacts plant-pollinator interactions and threatens the sustainability of plant species. Astragalus tragacantha (Fabaceae), is a rare endangered plant species along the coastal habitats where the plant populations have undergone considerable fragmentation and decline of size. Controlled pollination treatments, the observation of pollinator activity, and pollinator captures, have been conducted to study: (1) the mating system of A. tragacantha and the potential for inbreeding depression and/or outbreeding depression based on controlled pollination treatments, (2) the pollinator composition among populations using a correspondence analysis and a hierarchical clustering, and (3) the link between pollinators and the plant reproductive success using a path-analysis model. In this study, we demonstrated that this plant was not autogamous self-pollinating and depended on pollinators for its reproduction. The absence of difference between manual and open pollinations regarding the reproductive success showed an absence of pollen limitation in our populations. We showed that populations differed in the composition of their pollinator guilds. Some pollinator species were predominant in certain populations. The pollination treatments revealed the existence of a mixed mating system in A. tragacantha populations. We showed an inbreeding depression potentially linked to a predominant pollinator-facilitated selfing, and the existence of outbreeding depression between some distant populations. These differences in pollinator guild and plant mating systems among populations must be considered during the restoration of populations along the Mediterranean coastal habitats in order to enhance the reproductive success and sustainability of A. tragacantha. [ABSTRACT FROM AUTHOR]

Maximising genetic diversity in conservation efforts can help to increase the chances of survival of a species amidst the turbulence of the anthropogenic age. Here, we define the distribution and extent of genomic diversity across the range of the iconic but threatened Acacia purpureopetala, a beautiful sprawling shrub with mauve flowers, restricted to a few disjunct populations in far north Queensland, Australia. Seed production is poor and germination sporadic, but the species occurs in abundance at some field sites. While several thousands of SNP markers were recovered, comparable to other Acacia species, very low levels of heterozygosity and allelic variation suggested inbreeding. Limited dispersal most likely contributed towards the high levels of divergence amongst field sites and, using a generalised dissimilarity modelling framework amongst environmental, spatial and floristic data, spatial distance was found to be the strongest factor explaining the current distribution of genetic diversity. We illustrate how population genomic data can be utilised to design a collecting strategy for a germplasm conservation collection that optimises genetic diversity. For this species, inclusion of all field sites will capture maximum genetic diversity for both in situ and ex situ conservation. Assisted cross pollination, within and between field sites and genetically structured groups, is recommended to enhance heterozygosity particularly at the most disjunct sites and further fragmentation should be discouraged to avoid loss of genetic connectivity.

Halenia (Gentianaceae) originated from the mountain regions of East Asia, and diversified in America following long migrations via Beringia. While Halenia elliptica, one species of the genus in China, migrated toward high latitudes in China. Spur length of H. elliptica is highly variable. We examined the relationship between spur length and mating pattern along a latitude gradient. Field experiments were performed in two populations of H. elliptica, and we found that this species could produce seeds via both autonomous selfing and the aid of pollinators, suggesting a mixed mating system. In seven populations of H. elliptica along a latitudinal gradient, we found a trend of decrease in spur length with the increase of latitude. Based on molecular data from 11 microsatellite loci, we found that multilocus outcrossing rate decreased with the increase of latitude while the estimated inbreeding depression increased significantly, indicating that a high degree of inbreeding depression might have prevented evolution toward complete selfing in the high latitude populations with short spur length, and thus maintained mixed mating system of H. elliptica. Our results suggest that the mixed mating system of this species might be helpful in overcoming pollinator scarcity in newly colonized populations toward high latitudes after its origination in the mountain regions of China, and the decrease of spur length in the high latitude populations could result from reduced resource allocation to pollinator associated traits.

The rewarding orchid Epipactis flava was studied in NW Thailand. Its flowers were visited by a wide range of insects, most of which served as pollinators. The most frequent pollen bearers were (in decreasing order): the cricket Homoeoxipha lycoides, stingless bees of the Tetragonula testaceitarsis/hirashimai complex, hoverflies of subfam. Syrphinae, the wasp Polybioides gracilis and sweat bees of subfam. Halictinae. We found no evidence of a link between the rheophytic habit of E. flava and its pollinator fauna. Whereas most pollinators visited the flowers to feed on nectar, females of Episyrphus alternans (Syrphidae: Syrphinae) were observed to oviposit despite the absence of prey for their young. Hence, we suggest that dual pollination systems contribute to the opportunist strategy of E. flava, and we discuss, in a phylogenetic framework, how the strategy fits in with those previously reported for Epipactis sect. Arthrochilium. The elastic attachment of the epichile (a universal trait in sect. Arthrochilium) was found to promote outcrossing, and we hypothesize that loss of the elastic hinge has provided a key innovation facilitating recurrent evolution of obligate autogamy in sect. Epipactis (which is nested in sect. Arthrochilium). [ABSTRACT FROM AUTHOR]

Abstract: Hymenaea stigonocarpa is a neotropical tree that is economically important due to its high‐quality wood; however, because it has been exploited extensively, it is currently considered threatened. Microsatellite loci were used to investigate the pollen and seed dispersal, mating patterns, spatial genetic structure (SGS), genetic diversity, and inbreeding depression in H. stigonocarpa adults, juveniles, and open‐pollinated seeds, which were sampled from isolated trees in a pasture and trees within a forest fragment in the Brazilian savannah. We found that the species presented a mixed mating system, with population and individual variations in the outcrossing rate (0.53–1.0). The studied populations were not genetically isolated due to pollen and seed flow between the studied populations and between the populations and individuals located outside of the study area. Pollen and seed dispersal occurred over long distances (>8 km); however, the dispersal patterns were isolated by distance, with a high frequency of mating occurring between near‐neighbor trees and seeds dispersed near the parent trees. The correlated mating for individual seed trees was higher within than among fruits, indicating that fruits present a high proportion of full‐sibs. Genetic diversity and SGS were similar among the populations, but offspring showed evidence of inbreeding, mainly originating from mating among related trees, which suggests inbreeding depression between the seed and adult stages. Selfing resulted in a higher inbreeding depression than mating among relatives, as assessed through survival and height. As the populations are not genetically isolated, both are important targets for in situ conservation to maintain their genetic diversity; for ex situ conservation, seeds can be collected from at least 78 trees in both populations separated by at least 250 m. [ABSTRACT FROM AUTHOR]

Halenia (Gentianaceae) originated from the mountain regions of East Asia, and diversified in America following long migrations via Beringia. While Halenia elliptica, one species of the genus in China, migrated toward high latitudes in China. Spur length of H. elliptica is highly variable. We examined the relationship between spur length and mating pattern along a latitude gradient. Field experiments were performed in two populations of H. elliptica, and we found that this species could produce seeds via both autonomous selfing and the aid of pollinators, suggesting a mixed mating system. In seven populations of H. elliptica along a latitudinal gradient, we found a trend of decrease in spur length with the increase of latitude. Based on molecular data from 11 microsatellite loci, we found that multilocus outcrossing rate decreased with the increase of latitude while the estimated inbreeding depression increased significantly, indicating that a high degree of inbreeding depression might have prevented evolution toward complete selfing in the high latitude populations with short spur length, and thus maintained mixed mating system of H. elliptica. Our results suggest that the mixed mating system of this species might be helpful in overcoming pollinator scarcity in newly colonized populations toward high latitudes after its origination in the mountain regions of China, and the decrease of spur length in the high latitude populations could result from reduced resource allocation to pollinator associated traits. [ABSTRACT FROM AUTHOR]

Abstract: Recent work has improved our understanding of the linkages between above‐ and below‐ground interactions mediated by plants. However, relatively few of the studies conducted thus far have focused on multi‐trophic interactions (i.e. beyond two trophic levels) and the influence of plant genetic intraspecific variation on these dynamics has rarely been addressed. We tested the effect of arbuscular mycorrhizal fungi (AMF) on above‐ground tri‐trophic interactions associated with the canopy of the perennial herb Ruellia nudiflora, and further determined whether genetic effects due to cross type (i.e. whether a plant originated from self‐ or cross‐pollination) influenced these interactions. We propagated plants originating from self‐ or cross‐pollination, and within each category inoculated half of the plants with AMF. We subsequently established a common garden where plants were exposed to naturally occurring seed‐eating caterpillars and their parasitoids. We measured plant growth, fruit output, calculated the proportion of attacked fruits by the caterpillar and the proportion of parasitized caterpillars, and also estimated the proportion of “rescued” seeds by parasitoids representing an indirect positive effect of the third trophic level on the plant by reducing caterpillar consumption. Arbuscular mycorrhizal fungi drove 18% and 15% increases in plant growth and fruit output respectively, and drove a 25% reduction in caterpillar fruit attack, but did not influence parasitism or parasitoid seed “rescue.” In contrast, cross type did not influence growth, fruit number, herbivore attack, parasitism or seed rescue. More importantly, however, we found a significant AMF by cross type interaction on caterpillar attack, where AMF significantly reduced fruit attack (by 30%) in progeny from cross‐pollination but did not influence herbivory in progeny from self‐pollination. Synthesis. Results indicate that effects of arbuscular mycorrhizal fungi on above‐ground interactions are contingent upon plant intraspecific variation originating from cross type, which is likely a common source of variation in associated interactions for plants with mixed mating systems. Further studies examining plant‐mediated below‐ and above‐ground interactions should consider the influence of specific sources of plant genetic variation, as well as address the consequences of such dynamics for interactions beyond two trophic levels. [ABSTRACT FROM AUTHOR]

Bixa orellana L. (achiote), is a tropical species that produces high amounts of bixin, used as a commercial food pigment. In Yucatan, B. orellana (achiote) is cultivated under three different agronomic systems: backyard (solar), polyculture (milpa), and monoculture. Two promising phenotypes affecting bixin production have been identified. The phenotypes differ in flower and fruit colour, fruit dehiscence and bixin contents. Reflecting differences in plant density, species diversity and management factors among agronomic systems and differences in flowering synchrony between phenotypes, mating system parameters might vary, such as outcrossing rates ( t m and t s ), biparental inbreeding ( t m -t s ; r pm - r ps ), the fixation index of maternal plants ( F ) and paternity correlation ( r pm ). To compare such parameters between different B. orellana phenotypes among agronomic systems, 10 offspring from 20 genetic families of B. orellana per agronomic system were amplified using sequence-related amplified polymorphism (SRAP) molecular markers. MLTR software was used assuming a mixed mating system. Plants sown in backyard showed a mixed mating system, while in poly- and monoculture, they showed predominantly an outcrossing system; biparental inbreeding was similar in backyard, poly- and monoculture; the maternal inbreeding coefficient was higher in backyards than in poly- and monoculture; and plants in backyards and monoculture are less promiscuous than plants in polyculture. Variations between phenotypes within each agronomic system were also recorded. B. orellana displays a mixed mating system affected by the agronomic system. Thus, the selection of offspring should consider variation in the mating system in the design of alternative breeding improvement programs. [ABSTRACT FROM AUTHOR]

* Background and aims The transition from outcrossing to selfing is a repeated pattern in angiosperm diversification and according to general theory this transition should occur quickly and mixed reproductive systems should be infrequent. However, a large proportion of flowering plants have mixed reproductive systems, even showing inbreeding depression. Recently, several theoretical studies have shown that mixed mating systems can be stable, but empirical studies supporting these assumptions are still scarce. * Methods Hypochaeris salzmanniana, an annual species with populations differing in their self-incompatibility expression, was used as a study case to assess the stability of its mixed reproductive system. Here a descriptive study of the pollination environment was combined with measurements of the stability of the self-incompatibility system, outcrossing rate, reproductive assurance and inbreeding depression in four populations for two consecutive years. * Key Results The reproductive system of populations exhibited a geographical pattern: the proportion of plants decreased from west to east. Pollinator environment also varied geographically, being less favourable from west to east. The self-incompatibility expression of some populations changed markedly in only one year. After selfing, progeny was mainly self-compatible, while after outcrossing both self-incompatible and self-compatible plants were produced. In general, both reproductive assurance and high inbreeding depression were found in all populations and years. The lowest values of inbreeding depression were found in 2014 in the easternmost populations, which experienced a marked increase in self-compatibility in 2015. * Conclusions The mixed reproductive system of H. salzmanniana seems to be an evolutionarily stable strategy, with selfing conferring reproductive assurance when pollinator attendance is low, but strongly limited by inbreeding depression. The fact that the highest frequencies of self-compatible plants appeared in the environments most unfavourable to pollination suggests that these plants are selected in these sites, although high rates of inbreeding depression should impede the complete loss of self-incompatibility. In H. salzmanniana, year-to-year changes in the frequency of self-incompatible individuals are directly derived from the balance between reproductive assurance and inbreeding depression. [ABSTRACT FROM AUTHOR]

Plant mating systems rapidly respond to pollen limitation in changing environments. However, whether and how floral traits are involved in a mating system shift requires further investigation. A widely distributed and bumblebee-pollinated lousewort, Pedicularis siphonantha D. Don was studied. We investigated pollination systems, reproductive success, and floral traits in four large populations growing from 3200 m to 4300 m. Pollinator activity in low altitude populations was lower and these populations had a decreased fruit set and seed number per capsule compared to populations at high altitudes. Supplemental hand pollination with outcross pollen significantly increased seed production per capsule for plants from high altitudes but not for those from lower altitudes. We also found that bumblebees visited more flowers within an inflorescence in a single foraging bout in high altitudes compared with low altitudes, which caused a high possibility of geitonogamous mating. These differences may be pollination-dependent rather than inheritance-based because hand pollination on bagged flowers did not cause a difference in seed production across populations. Compared to plants from low altitudes, high-altitude plants had increased flower longevity, larger floral displays, higher pollen production per flower, and shorter corolla tubes, which were found to be well in accordance with changes in both pollination environment and mating system. Plasticity in floral traits might help plants to adjust their resource allocation strategies in response to their habitat, which might be linked with pollination environment. The variability among these populations might be beneficial for this widely distributed species to cope with environmental changes. [ABSTRACT FROM AUTHOR]

Fungal plant parasites represent a growing concern for biodiversity and food security. Most ascomycete species are capable of producing different types of infectious spores both asexually and sexually. Yet the contributions of both types of spores to epidemiological dynamics have still to been fully researched. Here we studied the effect of mate limitation in parasites which perform both sexual and asexual reproduction in the same host. Since mate limitation implies positive density dependence at low population density, we modeled the dynamics of such species with both density-dependent (sexual) and density-independent (asexual) transmission rates. A first simple SIR model incorporating these two types of transmission from the infected compartment, suggested that combining sexual and asexual spore production can generate persistently cyclic epidemics in a significant part of the parameter space. It was then confirmed that cyclic persistence could occur in realistic situations by parameterizing a more detailed model fitting the biology of the Black Sigatoka disease of banana, for which literature data are available. We discuss the implications of these results for research on and management of Sigatoka diseases of banana. [ABSTRACT FROM AUTHOR]

Polygala lewtonii is a federally endangered, amphicarpic plant with a mixed mating system and three types of flowers: (1) aboveground, chasmogamous flowers (i.e., open-pollinated; CH), (2) aboveground, cleistogamous flowers (i.e., closed, selfing; CL) and (3) CL flowers on belowground stems (amphicarpy). Aboveground seeds are ant-dispersed, whereas belowground seeds are spaced across the length of the rhizome. Here, we collected individuals of P. lewtonii at both range-wide and fine geographic scales and genotyped them at 11 microsatellite loci. We analyzed patterns of genetic diversity and structure to understand: (1) the predominant mating system (selfing or outcrossing), (2) the movement of pollen and seeds across the landscape, and (3) the optimal strategy to conserve the full range of genetic variation. P. lewtonii reproduces predominantly by selfing or bi-parental inbreeding, but reproduction occurred through each of the three flower types. Some individuals produced by selfing/inbreeding were tightly clustered spatially, and were likely produced either by belowground flowers or by aboveground flowers with limited seed dispersal. Other selfed/inbred individuals were spatially separated (maximum of 15 m), and were likely produced by aboveground flowers followed by seed dispersal by ants. Fine-scale patterns of genetic structure indicate that some gene flow is occurring among aboveground CH flowers but both pollen and outcrossed seeds are moving limited distances (maximum of 0.5 km). Because genetic variation is structured at a fine spatial scale, protecting many populations is necessary to fully conserve the genetic variation in P. lewtonii. Conservation seed banking, if accompanied by research on seed germination requirements, may also contribute to the effective protection of genetic variation in P. lewtonii. [ABSTRACT FROM AUTHOR]

The invasiveness and dissemination of exotic species are strongly influenced by its sexual reproduction characteristics, including blooming characteristics and breeding system. Exploring the association of these sexual reproductive traits with invasiveness would be helpful for revealing the mechanism of its successful invasion. We examined the blooming characteristics and breeding system of Gaura parviflora based on field observations, out-crossing index (OCI) estimation, and hand-pollination experiments. The results showed flowering duration of the G. parviflora population (flowering period) was short (more than 3 months). The life span of single flower (floral longevity) was 40.46 h. Its flower diameter was 3.99 mm. Over seven flowers in bloom per inflorescence and most individuals often bloomed synchronously, which showed a 'mass-flowering pattern'. The changing trend of pollen and stigma vitality was relatively similar, but the duration of stigma vitality was 2 h longer than that of pollen. The stigma and the anthers were close to each other at the initial flowering stage, but the stigma removed from the anthers at the full-blooming stage with the style curving downwards. Many pollinators visited flowers in late full-blooming stage, which were mainly Apis mellifera and Syrphidae spp. Their average visiting frequency was 9.8 times·m -2 ·h -1 . The fruit set in natural pollination after emasculation treatment (insect or wind pollination) was signi-ficantly higher than that in bagged and emasculation treatment, and the treatment of emasculated and bagged with nylon net (excluding insect pollination) could also bear fruits, indicating possible existence of ambophily in G. parviflora. The results of pollen ovule ratio (P/O) mensuration, OCI estimation and hand-pollination experiments showed that its mating system type belonged to additive mixed mating system. So, its characteristics, such as smaller flower size, shorter floral longevity and flowering period, were conducive to allocating more resources to plant growth and seed development, which would help improve its total fitness. The changes of spatial position of male and female organs not only avoided interference between male and female functions, but also created opportunities for stigmas to receive outcross pollen. In addition, the 'mass-flowering pattern' was conducive to attracting pollinators. The pollination mechanism of ambophily was helpful to ensure cross-pollination. The additive mixed mating system could provide double reproductive assurance for this species. These reproductive characteristics were significant for the successful invasion and expansion of G. parviflora .

Pollination becomes a constraint when conspecific plants and/or their pollinators become scarce. Many plant species have evolved autogamous self-pollination as a means of reproductive assurance (RA) under pollination-uncertain environments. So far RA has been studied and discussed largely with reference to self-compatible species producing bisexual flowers. RA seems to have evolved across all other sexual and breeding systems - monoecy, dioecy and self-incompatibility (SI). Both monoecy and dioecy produce bisexual flowers (andro/gyno-monoecy, andro/gynodioecy and polygamous conditions) which may provide RA. Similarly, most of the SI species are leaky and do set some seeds upon self-pollination. This phenomenon termed 'partial self-compatibility' is quite common and does provide RA in SI species. Although dioecy and SI have evolved as obligate outbreeding systems, they seem to have reached an evolutionary dead end because of the constraints for outcross pollination. In the light of habitat destruction leading to a reduction in the diversity and density of native pollinators, it is likely that many of the obligate outbreeders tend to shift to mixed mating system in the coming decades. Similarly, obligate mutualism in which each plant species is dependent on one animal species for pollination also seems to have reached a dead end and the trend is to abandon such obligate mutualism as a survival strategy. In the absence of such a change, obligate outbreeders and those with highly specialized pollination system are likely to become endangered or even extinct. [ABSTRACT FROM AUTHOR]

Se estudió la estrategia reproductiva de Hypoxis decumbens L. (Hypoxidaceae), una hierba perenne con flores hermafroditas, para comprobar las relaciones que se establecen entre sistema reproductivo, forma de vida, ambiente, sistema de polinización y otros caracteres morfológicos y ecológicos. H. decumbens es una especie altamente autógama, que presenta depresión por entrecruzamiento debido a la adaptación de los genotipos autógamos a su ambiente. Los principales polinizadores fueron insectos generalistas como los dípteros. Presentó flores funcionalmente solitarias, actinomórficas, con las partes florales bien expuestas, todas a la misma altura, y anteras de dehiscencia introrsa. La asignación de biomasa fue básicamente hacia estructuras femeninas, como frutos y semillas, lo que se reflejó en una alta eficiencia reproductiva. La relación polen/óvulo fue baja, lo mismo que la relación biomasa de atracción/biomasa de soporte. La unidad de dispersión fue la semilla y el síndrome de dispersión asociado fue la mirmecocoría. En esta especie se presenta un sistema reproductivo mixto, y aunque la mayor proporción de progenie es autógama, no sacrifica la oportunidad de entrecruzarse.The reproductive strategy of Hypoxis decumbens L. (Hypoxidaceae), a perennial herb with hermaphroditic flowers, was studied to check the relations between reproductive system, life form, habitat, pollination system and other morphological and ecological features. The study was done in a secondary deciduous forest with a population of 150-200 plants. Controlled pollinations were done in twenty isolated plants. The results pointed out that H. decumbens is an autogamous species, with outbreeding depression apparently reflecting environmental adaptation of the autogamous genotypes. The main pollinators were generalist insects, like dipterans. It has functionally solitary and actinomorphic flowers, with well exposed floral parts, displayed approximately at the same height, and with inner and before anthesis dehiscence of the anthers. The biomass allocation was mainly to female structures, like fruits and seeds, which was reflected in a low male-female biomass ratio, and in high fruit and seed set. The pollen-ovule and the attraction-support biomass ratios were low, associated with autogamous species, which have reliable pollination. The dispersal unit is the seed and the dispersal syndrome is myrmecochory, with the infructescence prostrate over the soil, the fruit with gradual dehiscence and with lipid droplets and placental remains (also with lipid content) in the seed coat. This species has several structural and functional attributes that sustain a mixed mating system and, although the results indicate that most of the progeny is autogamous; it does not sacrifice the opportunity for out-crossing.

Bromeliaceae is a Neotropical family that evolved ecological key innovations in association with extensive adaptive radiation. Its species present a variety of different mating system strategies varying within and among species, within genera and subfamilies. Also, species with a wide geographical range can display large variation in mating system, reproductive success and genetic diversity. Here we combined data from hand pollinations and genetic analysis to assess outcomes of contemporary gene flow and mating system variation at the range edge of Vriesea gigantea . Results from pollen germination rates showed that this species is cryptically self-incompatible. Hand-pollination experiments and genetic analysis of progeny arrays revealed that V . gigantea has a mixed mating system, with high selfing rates ( s = 0.612), and high inbreeding coefficient ( F = 0.372). Inbreeding in V . gigantea at southern edge of its distribution range was caused by high levels of selfing rather than by mating among relatives. Moreover, strong pollen pool genetic structure was observed (Φ’ FT = 0.671), with an increase from north to south. The parameters observed help us to understand historical and ecological conditions under which V . gigantea has experienced moderate to high levels of selfing in the face of reduced pollen flow from central to peripheral populations due to recent southward range expansion. [ABSTRACT FROM AUTHOR]

The Japanese endemic conifer Sciadopitys verticillata is one of the most phylogenetically isolated species of all plants. Occurring in small and scattered populations, the species is currently classified as Near Threatened by the International Union for Conservation of Nature and Natural Resources (IUCN) and as Vulnerable in three prefectures of Japan. This study investigated two major factors that should impact the genetic structure of the species at both the nuclear and organelle DNA level, the mating system and the inheritance of both the chloroplast and mitochondrial genomes. The mating system is crucial to determining the degree of outcrossing of plant species and thus should have a key role in shaping the species' population level genetic diversity and gene flow between populations but as yet has not been studied in S. verticillata. Nine mother trees and their seedling progeny from two natural populations were genotyped using genetic markers from three plant genomes (eight nuclear microsatellites and DNA sequence for the chloroplast and mitochondria). Using a maximum likelihood method implemented in the software MLTR, the study found an outcrossing rate in the seedling stage of 0.49 and 0.79 for Aburazaka and Mount Shirotori populations, respectively, and an average of 0.66 at the species level. These outcrossing rates were low for conifers and therefore may have potential deleterious implications for the conservation of the species. The test of organelle inheritance supported paternal transmission of both the chloroplast and mitochondria consistent with previous microscopic evidence. [ABSTRACT FROM AUTHOR]

Amphicarpy is a fascinating reproductive strategy, defined as fruit produced both below the soil surface and as aerial fruit on the same plant. Trifolium polymorphum is a grassland species subject to herbivory that combines amphicarpy with vegetative reproduction through stolons. Underground flowers have been described as obligate autogamous and aerial ones as self-compatible allogamous, with aerial floral traits favouring cross-pollination. In the present work we performed different pollination treatments on aerial flowers to analyse rates of pollen tube development and offspring fitness, measured as fruit set, seed production and germination percentage. This last variable was compared to that of seeds produced underground. No significant differences were found between fruit set in self- and cross-pollinations. Seed production was higher in self-pollinations, which is consistent with the higher rate of pollen tube development observed in self-crosses. Spontaneous self-pollination is limited in aerial flowers; thus pollen transfer by means of a vector is required even within the same flower. Germination tests showed that aerial seeds produced after self- and cross-pollination did not differ in fitness, but underground seeds had higher germination percentage than aerial ones. Thus, we conclude that T. polymorphum has a mixed mating system. In grasslands with heavy grazing pressure, clonal propagation and underground seed production ensure persistence in the field. An intermediate level of selfing in aerial flowers ensures offspring, but morphological (herkogamy) and functional (dicogamy) floral traits maintain a window to incorporate genetic variability, allowing the species to tolerate temporal and spatial pressures. [ABSTRACT FROM AUTHOR]

Temporal variation in morphological and life-history traits is directly linked to phenotypic plasticity in perennial plants. Phenotypic plasticity in reproductive phenology determines colonisation ability and population persistence in invasive weeds. We describe the reproductive phenology of Ruellia nudiflora (a cleistogamous weed) and assess the plasticity of its response to between-year environmental variation in two contrasting light environments. We recorded the flower and fruit production of focal plants under two experimental levels of light intensity (open vs. shaded) over two years. Our results suggest that light differentially affects the phenology of reproductive structures, but not between-year variation. Specifically, individual production of chasmogamous structures (flowers and fruit) ended earlier under shaded conditions than in the open, whilst production of cleistogamous fruits was not affected. At the population level, there was between-year variation in the phenology of chasmogamous structures, which were bimodal and unimodal in the first and second year respectively. At the individual level, we found very low repeatability, suggesting high levels of phenotypic plasticity. Temporal variation in rainfall did not explain phenological variation. Although shade did not affect between-year variation, it produced a briefer period of production of chasmogamous structures. This effect of shade may have some consequences for the genetic background of R. nudiflora's progeny, because only chasmogamous flowers can be out-crossed, and this therefore might be an important factor to consider when designing management strategies. [ABSTRACT FROM AUTHOR]

Delayed selfing has been considered the best-of-both-worlds response to pollinator unpredictability because it can provide reproductive assurance without decreasing outcrossing potential. According to this hypothesis, selfing rates in delayed selfing species should be highly variable in fluctuating pollinator environments. To test this prediction, as well to explore the consequences of delayed selfing on genetic patterns, we compared two sister species that grow in the high Andes of Chile: Schizanthus grahamii that exhibits delayed selfing and Schizanthus hookeri, which is self-compatible but requires pollinators for seed set. We estimated genetic diversity within and among five populations of each species using six shared microsatellites. Our results indicated that selfing rates in S. grahamii (range 0.07-0.81) were significantly more variable than in S. hookeri (range 0-0.26). The highest levels of selfing were found in the populations of S. grahamii located at highest altitudes (r = 0.78) and at northern margin range, where pollinators are probably more scarce. These populations also showed the lowest allelic richness and heterozygosity values. Southern populations of S. grahamii had mixed mating, and showed heterozygosity and diversity values close to those detected for S. hookeri along all the sampled range. Selfing in this species results from geitonogamy, and did not covary with altitude. Schizanthus grahamii showed greater population differentiation than S. hookeri. Overall, our results indicated that selfing rates were widely variable in S. grahamii, with some populations predominantly selfing and others showing mixed mating. This pattern may be associated with the strong fluctuations in pollinator service that typically occur in the high Andes of Chile. [ABSTRACT FROM AUTHOR]

Hurricanes are major disturbance events in Neotropical mangrove communities, potentially affecting the reproductive success of mangrove species. This was the first investigation of changes in mangrove pollinator assemblages following hurricanes, and the effect of these changes on the mating system of Laguncularia racemosa. Insect pollinator assemblages were investigated in three Florida mangrove communities in 2001–2003, 2005 and 2009; two hurricanes affected the area in 2004. Visitation rates were estimated from 1445 insects observed during 272 10-min intervals; the number of flowers visited by each insect was also recorded. Pollinator diversity was estimated with the Shannon Index. Following the hurricanes, species richness was reduced by 43–65% and diversity declined by 36–70%. Significant declines in insect visitation to L. racemosa resulted in reduced outcrossing frequencies in 2005. Laguncularia racemosa flowers autogamously self-pollinate without insect visitors, so fruit set still occurred. Visitation rates returned to pre-hurricane levels by 2009, but foraging behaviours differed from pre-hurricane patterns; outcrossing was further favoured by reduced frequencies of long foraging bouts and increased frequencies of short foraging bouts. The mixed mating system of L. racemosa provides reproductive assurance following hurricane disturbances, when pollinator abundance is low. [ABSTRACT FROM PUBLISHER]

Background and Aims Three ecological relationships are possible between co-flowering plant species; they may have no effect on one another, compete for pollination services, or facilitate one another by attracting more pollinators to the area. In this study, the pollinator-mediated relationship between two mangrove species with overlapping flowering phenologies was investigated in one south Florida community. Methods Pollinator observations were recorded between 0900 h and 1700 h during June and July, 2008–2010. Insect visitation rates to Avicennia germinans and Laguncularia racemosa were estimated from 522 observation intervals of 10 min during three phenological time periods, when each species flowered alone and when they co-flowered. The number of timed intervals varied between years due to differences in flowering phenology, from four to 42 for A. germinans and from nine to 94 for L. racemosa. Key Results Avicennia germinans began flowering first in all years, and insect visitation rates were significantly greater to A. germinans than to L. racemosa (P<0·001). Flowers of both species received visits from bees, wasps, flies and butterflies; Apis mellifera was the most common floral visitor to both species. Visitation rates to L. racemosa increased significantly when A. germinans stopped flowering (P<0·001). However, there was no significant change in visitation rates to A. germinans after L. racemosa began flowering (P=0·628). Conclusions When they co-flowered, A. germinans outcompeted L. racemosa for pollinators. Laguncularia racemosa hermaphrodites self-pollinate autogamously when not visited by insects, so reduced visitation to L. racemosa flowers reduced the frequency of outcrossing and increased the frequency of selfing. Reduced outcrossing limits male reproductive success in this androdioecious species, which could lead to changes in the breeding system. The degree of overlap in flowering phenologies varied between years, so the effect on the mating and breeding system may differ between years. [ABSTRACT FROM AUTHOR]

Inbreeding depression is a key factor affecting the persistence of natural populations, particularly when they are fragmented. In species with mixed mating systems, inbreeding depression can be estimated at the population level by regressing the average progeny fitness by the selfing rate of their mothers. We applied this method using simulated populations to investigate how population genetic parameters can affect the detection power of inbreeding depression. We simulated individual selfing rates and genetic loads from which we computed fitness values. The regression method yielded high statistical power, inbreeding depression being detected as significant (5 % level) in 92 % of the simulations. High individual variation in selfing rate and high mean genetic load led to better detection of inbreeding depression while high among-individual variation in genetic load made it more difficult to detect inbreeding depression. For a constant sampling effort, increasing the number of progenies while decreasing the number of individuals per progeny enhanced the detection power of inbreeding depression. We discuss the implication of among-mother variability of genetic load and selfing rate on inbreeding depression studies. [ABSTRACT FROM AUTHOR]

Background and Aims The frequency at which males can be maintained with hermaphrodites in androdioecious populations is predicted to depend on the selfing rate, because self-fertilization by hermaphrodites reduces prospective siring opportunities for males. In particular, high selfing rates by hermaphrodites are expected to exclude males from a population. Here, the first estimates are provided of the mating system from two wild hexaploid populations of the androdioecious European wind-pollinated plant M. annua with contrasting male frequencies. Methods Four diploid microsatellite loci were used to genotype 19–20 progeny arrays from two populations of M. annua, one with males and one without. Mating-system parameters were estimated using the program MLTR. Key Results Both populations had similar, intermediate outcrossing rates (tm = 0·64 and 0·52 for the population with and without males, respectively). The population without males showed a lower level of correlated paternity and biparental inbreeding and higher allelic richness and gene diversity than the population with males. Conclusions The results demonstrate the utility of new diploid microsatellite loci for mating system analysis in a hexaploid plant. It would appear that androdioecious M. annua has a mixed-mating system in the wild, an uncommon finding for wind-pollinated species. This study sets a foundation for future research to assess the relative importance of the sexual system, plant-density variation and stochastic processes for the regulation of male frequencies in M. annua over space and time. [ABSTRACT FROM AUTHOR]

Stylosanthes capitata and S. guianensis are important forage legumes for tropical areas. The only available estimates of S. capitata and S. guianensis outcrossing rates were based on morphological markers, and the genus is considered as being mainly self-pollinated. Here we describe an estimation of the outcrossing rate in S. capitata and S. guianensis using microsatellite markers. The outcrossing rates were estimated in S. capitata and S. guianensis open-pollinated populations of 20 progenies consisting of ten individuals each. The multi locus outcrossing rate for S. capitata was estimated using 10 polymorphic loci, whereas five microsatellites were used for S. guianensis. The multi locus outcrossing rates for S. capitata and S. guianensis were 31 and 26%, respectively, suggesting a mixed mating system with predominance of autogamy. Comparison of single locus and multi locus estimates of outcrossing rates indicated that little inbreeding other than selfing occurred. The estimated Wright's fixation index of the parental generation was lower than expected based on the multi locus outcrossing rate, possibly resulting from the use of some heterozygous breeding genotypes for the study. The data on the outcrossing rate described here are potentially useful for breeding programs and for maintenance of germplasm collections of these Stylosanthes species. [ABSTRACT FROM AUTHOR]

Background and Aims Human-mediated environmental change is increasing selection pressure for the capacity in plants to colonize new areas. Habitat fragmentation combined with climate change, in general, forces species to colonize areas over longer distances. Mating systems and genetic load are important determinants of the establishment and long-term survival of new populations. Here, the mating system of Asplenium scolopendrium, a diploid homosporous fern species, is examined in relation to colonization processes. Methods A common environment experiment was conducted with 13 pairs of sporophytes, each from a different site. Together they constitute at least nine distinct genotypes, representing an estimated approx. 95 % of the non-private intraspecific genetic variation in Europe. Sporophyte production was recorded for gametophytes derived from each parent sporophyte. Gametophytes were grown in vitro in three different ways: (I) in isolation, (II) with a gametophyte from a different sporophyte within the same site or (III) with a partner from a different site. Key Results Sporophyte production was highest in among-site crosses (III), intermediate in within-site crosses (II) and was lowest in isolated gametophytes (I), strongly indicating inbreeding depression. However, intragametophytic selfing was observed in most of the genotypes tested (eight out of nine). Conclusions The results imply a mixed mating system in A. scolopendrium, with outcrossing when possible and occasional selfing when needed. Occasional intragametophytic selfing facilitates the successful colonization of new sites from a single spore. The resulting sporophyte, which will be completely homozygous, will shed large amounts of spores over time. Each year this creates a bed of gametophytes in the vicinity of the parent. Any unrelated spore which arrives is then selectively favoured to reproduce and contribute its genes to the new population. Thus, while selfing facilitates initial colonization success, inbreeding depression promotes genetically diverse populations through outcrossing. The results provide further evidence against the overly simple dichotomous distinction of fern species as either selfing or outcrossing. [ABSTRACT FROM PUBLISHER]

Synchronous monocarpy in long-lived plants is often associated with pollination by wind, in part because infrequent mass flowering may satiate pollinators. Selfing in synchronous monocarps may provide reproductive assurance but conflict with the benefits of outcrossing, a key evolutionary driver of synchrony. We predicted that animal-pollinated species with synchronous flowering would have unspecialised flowers and attract abundant generalised pollinators, but predictions for selfing and outcrossing frequencies were not obvious. We examined the pollination biology of Isoglossa woodii (Acanthaceae), an insect-pollinated, monocarpic herb that flowers synchronously at 4–7-year intervals. The most frequent visitor to I. woodii flowers was the African honeybee, Apis mellifera adansonii. Hand-pollination failed to enhance seed production, indicating that the pollinators were not saturated. No seed was set in the absence of pollinators. Seed set was similar among selfed and outcrossed flowers, demonstrating a geitonogamous mixed-mating strategy with no direct evidence of preferential outcrossing. Flowers contained four ovules, but most fruits only developed one seed, raising the possibility that preferential outcrossing occurs by post-pollination processes. We argue that a number of the theoretical concerns about geitonogamous selfing as a form of reproductive assurance do not apply to a long-lived synchronous monocarp such as I. woodii. [ABSTRACT FROM AUTHOR]

Examinations of breeding system transitions have primarily concentrated on the transition from hermaphroditism to dioecy, likely because of the preponderance of this transition within flowering plants. Fewer studies have considered the reverse transition: dioecy to hermaphroditism. A fruitful approach to studying this latter transition can be sought by studying clades in which transitions between dioecy and hermaphroditism have occurred multiple times. Freshwater crustaceans in the family Limnadiidae comprise dioecious, hermaphroditic and androdioecious (males + hermaphrodites) species, and thus this family represents an excellent model system for the assessment of the evolutionary transitions between these related breeding systems. Herein we report a phylogenetic assessment of breeding system transitions within the family using a total evidence comparative approach. We find that dioecy is the ancestral breeding system for the Limnadiidae and that a minimum of two independent transitions from dioecy to hermaphroditism occurred within this family, leading to (1) a Holarctic, all-hermaphrodite species, Limnadia lenticularis and (2) mixtures of hermaphrodites and males in the genus Eulimnadia. Both hermaphroditic derivatives are essentially females with only a small amount of energy allocated to male function. Within Eulimnadia, we find several all-hermaphrodite populations/species that have been independently derived at least twice from androdioecious progenitors within this genus. We discuss two adaptive (based on the notion of ‘reproductive assurance’) and one nonadaptive explanations for the derivation of all-hermaphroditism from androdioecy. We propose that L. lenticularis likely represents an all-hermaphrodite species that was derived from an androdioecious ancestor, much like the all-hermaphrodite populations derived from androdioecy currently observed within the Eulimnadia. Finally, we note that the proposed hypotheses for the dioecy to hermaphroditism transition are unable to explain the derivation of a fully functional, outcrossing hermaphroditic species from a dioecious progenitor. [ABSTRACT FROM AUTHOR]

Mixed mating systems often evolve despite strong inbreeding depression, but there have been few experimental tests of this observation. Kosteletzkya virginica, a perennial dicot halophytic species of the Family Malvaceae, is native to brackish portions of coastal tidal marsh in the United States of America and was introduced into China in 1993. Pollination of K. virginica occurs through insect vectors and by delayed self-pollination via stylar movement. In the same two naturalized populations of K. virginica during 2005–2007, we measured (i) inbreeding depression across a range of life-cycle stages, (ii) pollination failure rate, and (iii) selfing rate estimated by AFLP markers. Results indicate that inbreeding depression values for the two naturalized populations during 2005–2007 ranged from 0.620 ± 0.036 to 0.656 ± 0.032, and mean inbreeding depression was 0.640 ± 0.006. Pollinator failure rates at the two naturalized K. virginica populations during 2005–2007 ranged from 0.091 ± 0.039 to 0.174 ± 0.061, and selfing rate ranged from 0.247 ± 0.018 to 0.468 ± 0.031. Population selfing rates are significantly and positively correlated with field estimates of pollinator failure ( P = 0.008 < 0.01, R2 = 0.857). Our data provide an empirical demonstration of a mixed mating system response to the pollinator environment in the presence of strong inbreeding depression. [ABSTRACT FROM AUTHOR]

In plant species with mixed mating systems, differences in diverse factors—including their pollination system, flowering phenology, life form and susceptibility to inbreeding depression—cause variation in outcrossing rates among fruits within individuals, among individuals within populations and among populations within species. To quantify this hierarchical variation, we examined outcrossing rates at the seed stage in five populations of Magnolia stellata, a self-compatible, insect-pollinated and protogynous tree species. For this purpose, we sampled 1498 seeds within 204 fruits obtained from 56 individuals of the five populations, determined genotypes of the sampled seeds and maternal individuals at six polymorphic microsatellite loci, then estimated outcrossing rates and their variance components at four hierarchical levels (fruits, individuals, populations and species) using a nested analysis of variance-type linear model with a Bayesian approach. The species-level outcrossing rate was 0.730 (95% credible interval, 0.595–0.842), indicating that this species has a mixed mating system. Outcrossing rates were not significantly different among populations, but were significantly different among individuals within populations. Variance components at the levels of individual and fruit were statistically supported and were highest for the former. Thus, factors influencing outcrossing rates at the individual level, such as differences in flowering phenology and early-stage inbreeding depression, appear to have important effects within these M. stellata populations, but not among them. The method of hierarchically estimating outcrossing rates using a Bayesian approach, as applied in this study, is compared with conventional methods for estimating outcrossing rates, and the statistical properties of the Bayesian approach are discussed.Heredity (2009) 102, 381–388; doi:10.1038/hdy.2008.128; published online 14 January 2009 [ABSTRACT FROM AUTHOR]

The extent of changes in genetic diversity and life-history traits associated with farming was investigated in the haploid–diploid red alga, Gracilaria chilensis, cultivated in Chile. This alga belongs to one of the most frequently cultivated seaweed genera around the world. Fifteen farmed populations, 11 wild populations, and two subspontaneous populations were sampled along the Chilean coast. The frequency of reproductive versus vegetative individuals and of haploid versus diploid individuals was checked in each population. In addition, the distribution of genetic variation in wild and cultivated populations was analyzed using six microsatellite markers. Our results first demonstrated that farmed populations are maintained almost exclusively by vegetative propagation. Moreover, the predominance of diploid individuals in farms showed that farming practices had significantly modified life-history traits as compared to wild populations. Second, the expected reduction in genetic diversity due to a cultivation bottleneck and subsequent clonal propagation was detected in farms. Finally, our study suggested that cultural practices in the southern part of the country contributed to the spread of selected genotypes at a local scale. Altogether, these results document for the first time that involuntary selection could operate during the first step of domestication in a marine plant. [ABSTRACT FROM AUTHOR]

Flowering synchrony is essential for plant reproductive success, especially in the case of small-sized populations of self-incompatible species. Closely related to synchrony, flowering intensity influences pollinator attraction and pollinator movements. Thus, a high flowering intensity may increase pollinator attraction but, at the same time, may also increase the probability of geitonogamous pollinations. Depending on the mating system, the female fitness of plants in small populations may be affected by both the positive effects of higher flowering synchrony and pollinator attraction and the negative effects of geitonogamous pollinations induced by a high flowering intensity. It was hypothesized that different-sized plants in a population would show contrasting flowering patterns, resulting in differences in pollinator behaviour. These influences could result in differences in mating and female reproductive success. This hypothesis was tested by studying the flowering pattern of Erodium paularense (Geraniaceae), a rare and endangered endemic of central Spain. The temporal distribution of flower production was explored throughout the reproductive season, and the probability of xenogamy and geitonogamy and their relationship to plant size and fitness components were calculated. The analysis of this partially self-compatible species showed diverse flowering patterns related to different plant sizes. Small plants produced a larger number of seeds per fruit in spite of having lower values of flowering synchrony. By contrast, large plants produced a larger number of seeds from geitonogamous pollinations. The effect of different flower displays and outcrossing rates on seed set varied throughout the season in the different groups. Our findings highlight the relevance of individual plant size-dependent phenology on female reproductive success and, in particular, on the relationship between flowering synchrony and fitness. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 227–236. [ABSTRACT FROM AUTHOR]

To increase our knowledge about mating-system evolution, we need to understand the relationship between specific floral traits and mating system. Species of Collinsia (Plantaginaceae) vary extensively in mating system; this variation is associated with variation in floral morphology and development and with the timing of self-pollination. Counterintuitively, large-flowered, more outcrossing species tend to have delayed stigma receptivity, reducing the amount of time that the stigma is receptive to cross-pollination before autonomous self-pollination. To understand how the timing of stigma receptivity is related to mating-system evolution, we studied in detail the timing of both stigma receptivity and self-pollination (anther-stigma contact) in two greenhouse-grown populations of large-flowered Collinsia heterophylla. Crosses on emasculated flowers at different stages of floral development always produced seeds, suggesting that cross-fertilization can be effected by pollen arriving prior to physiological receptivity. Phenotypic and genetic variation within populations in the timing of stigma receptivity and anther-stigma contact was substantial, although slightly less for the contact. Despite strong interspecific and interpopulation correlations, we did not find an among-genet phenotypic correlation between the traits. This indicates that each trait may respond independently to selection, and the trait association may be the result of correlational selection. [ABSTRACT FROM AUTHOR]

As a step toward understanding how community context shapes mating system evolution, we investigated the combined role of two plant antagonisms, vegetative herbivory and intraspecific competition, for reproduction and mating system expression (relative production of selfing, cleistogamous and facultatively outcrossing, chasmogamous flowers and fruits) of Impatiens capensis. In a survey of I. capensis populations, we found that vegetative herbivory and intraspecific competition were positively correlated. In a greenhouse experiment where leaf damage and plant density were manipulated, multispecies interactions had dramatic effects on reproductive and mating system traits. Despite having additive effects on growth, herbivory and competition had nonadditive effects for mating system expression, chasmogamous fruit production, flower number and size, and cleistogamous flower production. Our results demonstrate that competitive interactions influence the effect of herbivory (and vice versa) on fitness components and mating system, and thus antagonisms may have unforeseen consequences for mating system evolution, population genetic diversity, and persistence. [ABSTRACT FROM AUTHOR]

Inbreeding depression and selfing rate were investigated in the self-compatible vine Ipomoea hederacea to assess the variability of the breeding system. Inbreeding depression differed between populations and the magnitude varied at germination, growth (as measured by aboveground biomass), and reproductive potential. Plants from Macon County, Alabama, USA, had significant inbreeding depression (31 %) at germination, but no significant inbreeding depression for aboveground biomass or number of reproductive structures (buds and flowers) at 45 d post germination in the greenhouse or in the field. Plants from Morgan County, Alabama, however, had significant inbreeding depression (>50%) for all three stages in the greenhouse. In allozyme comparisons, five of the 11 I. hederacea populations surveyed had high selfing rates (66.66-92.53%) and high levels of homozygosity (FIS = 0.500-0.861) in 2003, and three of four populations surveyed in 2004 had selfing rates that exceeded 50%. High selfing rates, high levels of homozygosity, and low levels of inbreeding depression suggest that inbreeding depression may not present a significant barrier to the transmission of selfing alleles in some populations of I. hederacea, but does not account for the maintenance of a mixed mating system in other populations. [ABSTRACT FROM AUTHOR]

Many flowering plants rely on pollinators, self-fertilization, or both for reproduction. We model the consequences of these features for plant population dynamics and mating system evolution. Our mating systems-based population dynamics model includes an Allee effect. This often leads to an extinction threshold, defined as a density below which population densities decrease. Reliance on generalist pollinators who primarily visit higher density plant species increases the extinction threshold, whereas autonomous modes of selfing decrease and can eliminate the threshold. Generalist pollinators visiting higher density plant species coupled with autonomous selfing may introduce an effect where populations decreasing in density below the extinction threshold may nonetheless persist through selfing. The extinction threshold and selfing at low density result in populations where individuals adopting a single reproductive strategy exhibit mating systems that depend on population density. The ecological and evolutionary analyses provide a mechanism where prior selfing evolves even though inbreeding depression is greater than one-half. Simultaneous consideration of ecological and evolutionary dynamics confirms unusual features (e.g., evolution into extinction or abrupt increases in population density) implicit in our separate consideration of ecological and evolutionary scenarios. Our analysis has consequences for understanding pollen limitation, reproductive assurance, and the evolution of mating systems. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that the previously recorded higher outcrossing rates and numbers of seeds per capsule from the upper, than from the lower, branches of trees ofEucalyptus globulus(Myrtaceae) is the result of greater pollinator activity in the upper parts of the canopy. Observations of bird pollinators on 23 trees, with flowers distributed evenly between the upper and lower halves of canopies, supported this hypothesis. Birds spent significantly more time foraging, and commenced foraging significantly more often, in the upper halves than in the lower halves of canopies. Flowers in the upper halves ofE. globuluscanopies would therefore be expected to receive more outcross-pollen from bird pollinators because they are usually visited more often and would probably receive a greater ratio of outcross- to self-pollen. We propose that such variation in pollinator activity and outcross-pollen deposition results in different selective pressures on the mating system and pollination syndrome in different parts of the canopy. This may result in balanced selection for these traits, contributing to the maintenance of the mixed mating and generalized pollination systems ofE. globulus. [ABSTRACT FROM AUTHOR]