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Invasive species present serious problems for ecosystems and economies. One such species, the invasive cutleaf coneflower (Rudbeckia laciniata L.), has several modes of seed dispersal, namely autochory, anemochory, epizoochory, myrmecochory and anthropochory. Because we found caches of this invasive plant's seeds in two nest boxes, suggesting the possibility of synzoochory, we report here the details of the caches. In one of the boxes, many of the seeds were cached in autumn and eaten during the winter. Automatic sensor cameras directed at the boxes revealed that three rodent species and two avian species visited the boxes. The characteristics of the caches and the nest-box visitors suggested that the small Japanese field mouse (Apodemus argenteus Temm.) was the animal most likely to have cached the seeds in the boxes.

Myrmecochory or seed dispersal by ants is often described as a diffuse mutualism, because many of the ant species that function as partners are considered to be similar in terms of the frequency and consequences of their interactions. In this work, we test this assumption by conducting ant community surveys and seed removal experiments in six study sites located within a semi-arid region of northwest Argentina. At each site, we characterized the ant assemblage that interacted with the seeds of Jatropha excisa Griseb. (Euphorbiaceae), an ant-dispersed native shrub. Our results demonstrate that seed removal was dominated by one species, Pogonomyrmex cunicularius Mayr (Hymenoptera: Formicidae: Myrmicinae), which was responsible of 84% of the observed seed removal events. Although several ant species were attracted to the elaiosome-bearing seeds of J. excisa, seed removal did not depend on ant community composition (species richness and ant activity) but was significantly influenced by the abundance of P. cunicularius. Its physical, behavioral, and ecological attributes are common with other ant species that have been characterized as keystone seed dispersers in other regions of the world. Nest feeding with marked seeds revealed that once P. cunicularius ants consume the elaiosomes, seeds are left inside the nests undamaged and at an appropriate depth for emergence. Our results support the hypothesis that myrmecochory is often an unevenly diffuse mutualism (i.e., one partner species is particularly important) and that at a local scale P. cunicularius is the keystone seed disperser of J. excisa.

Seed dispersal by ants, known as myrmecochory, is commonly observed among various plant taxa. The seeds of these plants have an elaiosome to attract ants. In Japan, myrmecochory has been well studied in several lowland plant species, but not in highland plant species that grow above the tree line. We investigated whether the seeds of Dicentra peregrina, known as the “queen of the alpine plants” in Japan, are carried by Formica gagatoides ants at 2510 m a.s.l. on Mt Norikura, Kita-Alps, Japan. We observed F. gagatoides workers picking up D. peregrina seeds by grasping the elaiosome and carrying the seeds into their nests. We inferred from the observed ant behavior and the seed morphology that D. peregrina is a myrmecochorous species.

This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for self-archiving., The fire avoidance hypothesis proposes that a benefit of seed dispersal by ants (myrmecochory) is to protect seeds from being killed during fire and to facilitate post-fire germination of seeds that require heat shock to break their physical dormancy. The aim of this study was to quantify the effect of fire and seed burial by a predominant seed-dispersing ant, Rhytidoponera metallica (subfamily: Ectatomminae) on germination levels of three ant-dispersed legume species (Pultenaea daphnoides, Acacia myrtifolia and Acacia pycnantha). Experimental burial of seeds within aluminium cans at a site prior to being burnt and at an adjacent unburnt site showed that fire increased germination levels, particularly for seeds buried at 1- and 2-cm deep and that overall, germination levels differed among the three plant species. To quantify seed burial depths and post-fire germination levels facilitated by R. metallica ants, seeds were fed to colonies prior to fire at the burnt and unburnt sites. Of the seeds buried within nests that were recovered, between 45% and 75% occurred within the upper 6 cm of the soil profile, although unexpectedly, greater percentages of seeds were recovered from the upper 0–2 cm of nests in the unburnt site compared with nests in the burnt site. Germination levels of buried seeds associated with R. metallica nests ranged from 21.2% to 29.5% in the burnt site compared with 3.1–14.8% in the unburnt site. While increased seed germination levels were associated with R. metallica nests following fire, most seeds were buried at depths below those where optimal temperatures for breaking seed dormancy occurred during the fire. We suggest that R. metallica ants may provide fire avoidance benefits to myrmecochorous seeds by burying them at a range of depths within a potential germination zone defined by intra- and inter-fire variation in levels of soil heating., This research was funded by the Wildlife Conservation Fund, the Native Vegetation Council of South Australia and the Mark Mitchell Research Foundation.

In the process of seed dispersal by ants (myrmecochory), foragers bring diaspores back to their nest, then eat the elaiosome and usually reject viable seeds outside the nest. Here, we investigate what happens inside the nest, a barely known stage of the myrmecochory process, for two seed species (Viola odorata, Chelidonium majus) dispersed either by the insectivorous ant Myrmica rubra or by the aphid-tending ant Lasius niger. Globally, elaiosome detachment decreased ants' interest towards seeds and increased their probability of rejecting them. However, we found marked differences in seed management by ants inside the nest. The dynamics of elaiosome detachment were ant- and plant-specific whereas the dynamic of seed rejection were mainly ant-specific. Seeds remained for a shorter period of time inside the nest of the carnivorous ant Myrmica rubra than in Lasius niger nest. Thus, elaiosome detachment and seed rejection were two competing dynamics whose relative efficiency leads to variable outcomes in terms of types of dispersed items and of nutrient benefit to the ants. This is why some seeds remained inside the nest even without an elaiosome, and conversely, some seeds were rejected with an elaiosome still attached. Fresh seeds may be deposited directly in contact with the larvae. However, the dynamics of larvae-seeds contacts were also highly variable among species. This study illustrates the complexity and variability of the ecological network of ant-seed interactions. © 2010 The Ecological Society of Japan., SCOPUS: ar.j, info:eu-repo/semantics/published

To investigate whether extrafloral nectar (EFN) increases seed dispersal in Turnera ulmifolia, we measured seed removal on plants with and without EFN. Plants producing EFN had more seeds removed than control plants, suggesting that EFN does play a role in seed dispersal. This is a novel function of EFN.

Summary 1. Deceptive species are a characteristic trait of insect–plant mutualisms. Deception of pollinators is essential for reproduction in diverse plant species; however, mimicry in seed dispersal is almost unknown. Myrmecochory, the dispersal of diaspores by ants, is a mutualism in which the elaiosome, a lipid-rich seed appendage, works as an ant reward. This coevolved interaction may be exploited by cheating, non-rewarding diaspores that mimic elaiosomes. 2. Our study assesses the impact of the morphology and fatty acid composition of diaspores on ant dispersal in rewarding and cheating myrmecochores and non-myrmecochorous species. Four elaiosome types (defined by Sernander 1906) were included in our research: the ‘Viola odorata type’, with a clearly defined elaiosome, the similar but diplochorous ‘Euphorbia type’ with an additional ballistic dispersal of diaspores, and the ‘Puschkinia’ and ‘Hepatica’ types, which we classify as ‘cheaters’ as they mimic ant rewards by chemical cues. 3. We tested the influence of morphology, chemical composition of diaspores and presence of rewards on removal rates of diaspores, dummies impregnated with seed extracts and pure fatty acids and scent-standardized diaspores in a population of Formica polyctena ants with 10 European spring ephemerals, mostly Ranunculaceae. The main free fatty acids of diaspores were identified by gas chromatography and mass spectrometric analysis. 4. Removal rates of diaspores and dummies treated with seed extracts were significantly influenced by their fatty acid composition. Discriminant function analysis confirmed oleic acid as the main trigger substance eliciting seed-removal behaviour by ants in most species. Oleic acid content and removal rates differed among elaiosome types and were highest in rewarding myrmecochores, lower in cheaters and smallest in non-myrmecochorous seeds. Removal rates of scent-standardized diaspores did not differ among mutualists and cheaters suggesting a selective pressure for morphological adaptation and were lowest in non-myrmecochorous species, thus corroborating an influence of diaspore morphology on ant-removal patterns. 5. For the first time, we demonstrate chemical mimicry in myrmecochory as a means of seed dispersal. Evolutionary stability of the ant–seed mutualism is maintained by the ability of ants to discriminate between certain types of rewards and to respond with differential diaspore distribution rates.

Ants frequently interact with fleshy fallen diaspores (fruits or seeds) not adapted for ant-dispersal. Such interactions are usually considered as opportunistic, but recent evidence has indicated that these ants may differ in their effects on diaspore survival and plant recruitment. We investigated if partner choices are recognizable among genera of ants and plants, and if ant and plant traits may influence such preferences in cerrado (savanna-like vegetation) from southeast Brazil. During a 2-yr period, 521 ant–diaspore interactions were recorded through various methods, yielding 71 ant species and 38 plant species. Exploitation of fallen diaspores was common among several ant genera, and included carnivorous, omnivorous, and fungivorous ants. Contrary to others areas around the world, where true myrmecochory (seed dispersal by ants) is common among shrubs, ants also exploited diaspores from several cerrado trees. Plant life form, diaspore size, and ant body size did not seem to explain the pattern of interactions observed. Two subsets of preferential interactions, however, segregated fungivorous ants from another group composed of carnivorous and omnivorous ants, probably influenced by the chemical composition of the plant diaspores. Omnivorous ants usually remove the fleshy portion of diaspores on spot and probably provide limited benefits to plants. Carnivorous and fungivorous ants usually remove the whole diaspore to the nest. As each of these ant groups may influence the fitness of diaspores in different ways, there are possible subtle pathways for the evolution of partner choices between ants and these non-myrmecochorous diaspores.

Species-specific climate responses within ecological communities may disrupt the synchrony of co-evolved mutualisms that are based on the shared timing of seasonal events, such as seed dispersal by ants (myrmecochory). The spring phenology of plants and ants coincides with marked changes in temperature, light and moisture. We investigate how these environmental drivers influence both seed release by early and late spring woodland herb species, and initiation of spring foraging by seed-dispersing ants. We pair experimental herbaceous transplants with artificial ant bait stations across north- and south-facing slopes at two contrasting geographic locations. This use of space enables robust identification of plant fruiting and ant foraging cues, and the use of transplants permits us to assess plasticity in plant phenology. We find that warming temperatures act as the primary phenological cue for plant fruiting and ant foraging. Moreover, the plasticity in plant response across locations, despite transplants being from the same source, suggests a high degree of portability in the seed-dispersing mutualism. However, we also find evidence for potential climate-driven facilitative failure that may lead to phenological asynchrony. Specifically, at the location where the early flowering species (Hepatica nobilis) is decreasing in abundance and distribution, we find far fewer seed-dispersing ants foraging during its fruit set than during that of the later flowering Hexastylis arifolia. Notably, the key seed disperser, Aphaenogaster rudis, fails to emerge during early fruit set at this location. At the second location, A. picea forages equally during early and late seed release. These results indicate that climate-driven changes might shift species-specific interactions in a plant‐ant mutualism resulting in winners and losers within the myrmecochorous plant guild.

Myrmecochory (seed dispersal by ants) is a common seed dispersal strategy of plants in fire-prone sclerophyll vegetation of Australia, yet there is little understanding of how fire history may influence this seed dispersal mutualism. We investigated the initial fate of seeds of two myrmecochorous plant species, the small-seeded Pultenaea daphnoides J.C. Wendl. and the large-seeded Acacia pycnantha Benth., in replicated burnt (3.25 years since fire) and unburnt (53 years since fire) forest plots in the Mount Lofty Ranges, South Australia. Specifically we measured (i) seed removal rates; (ii) the frequency of three ant–seed interactions (seed removal, elaiosome robbery and seed ignoring); (iii) the relative contribution of different ant species to ant–seed interactions; and (iv) the abundance of common interacting ant species. Rates of seed removal from depots and the proportion of seeds removed were higher in recently burnt vegetation and the magnitude of these effects was greater for the smaller-seeded P. daphnoides. The overall proportion of elaiosomes robbed was higher in unburnt vegetation; however, the decrease in elaiosome robbery in burnt vegetation was greater for P. daphnoides than for A. pycnantha. Ants ignored seeds more frequently in burnt vegetation and at similar rates for both seed species. In total, 20 ant species were observed interacting with seeds; however, three common ant species accounted for 66.3% of ant–seed interactions. Monomorium sydneyense almost exclusively robbed elaiosomes, Rhytidoponera metallica typically removed seeds and Anonychomyrma nr. nitidiceps showed a mix of the three behaviours towards seeds. Differences in the proportions of seeds removed, elaiosomes robbed and seeds ignored appeared to be largely driven by an increase in abundance of A. nr. nitidiceps and a decrease in abundance of M. sydneyense in burnt vegetation. Understanding how these fire-driven changes in the initial fate of myrmecochorous seeds affect plant fitness requires further investigation.

Myrmecochory (seed dispersal by ants) is an evolutionarily and ecologically common mutualism. Since the first study of the phenomenon, ecologists have sought to develop techniques to track ant-dispersed seeds. Often, thick leaf litter and the potential burial of seeds by ants make tracking of seeds difficult. Here we describe a seed-tracking technique for small seeds, which uses magnetic tags, developed for mark–recapture studies of fish, to track seeds after dispersal into the ant nest in temperate deciduous forests. We discuss our use of the technique as well as suggestions for improvement and other possible applications of the technique.

Summary 1. Whereas classic niche theory is based on the contraction of the niche via negative interactions, facilitative niche theory suggests that mutualisms can expand the niche via positive interactions. Specifically, animal-mediated seed dispersal can expand the utilization of physical space by plants and allow greater access to resources and other environmental requirements. Ant-mediated dispersal of plant propagules (myrmecochory) is a common mutualism throughout the world, particularly in the deciduous forests of the eastern United States where this research is conducted. 2. We examine two facets of niche expansion via ant-mediated seed dispersal: (1) increased utilization of resources along resource gradients and (2) escape from unfavourable density-dependent conditions. 3. We test these assumptions by introducing Hexastylis arifolia seeds in cafeteria-style bait stations along abiotic gradients (moisture, temperature, light) for removal by key seed dispersers from the ant genus Aphaenogaster. We also examine plant aggregation along the same gradients. 4. Ant-mediated dispersal services decrease significantly with increasing soil moisture and ultimately fail at levels that are demonstratively within the plant’s niche optima; further, the decline in dispersal services is correlated with increasing plant aggregation, suggesting that enemy escape also falters at relatively high levels of soil moisture. 5. Synthesis. Facilitated propagule dispersal fails to expand the Hexastylis arifolia niche in either enhanced resource utilization or decreased density dependence as the niche requirements for the ant disperser are nested within those for the plant. The strength of this interaction varies across space and time, and in doing so may undermine attempts to predict future distributions. Further, given that myrmecochores are typically poor dispersers, the incomplete niche overlap between the plant and its facilitator makes this plant guild particularly susceptible to climatic change if each participant responds individually to shifting environmental conditions.

Ant-dispersed herbs (myrmecochores) can account for more than one-third of the stems in the temperate deciduous forests of eastern North America. Because many ant species have been observed collecting the seeds, this interaction is often described as a generalized mutualism. Here, we combine fieldwork and meta-analyses to test this assumption. Our meta-analysis demonstrated that Aphaenogaster ants (predominantly A. rudis) collect approximately 74±26% (mean± SD) of the myrmecochorous seeds in eastern North American forests where any encounters with Aphaenogaster were reported, and approximately 61 ±37% of the seeds in all the eastern forests where any seed collection has been monitored. This remarkable monopolization of seeds is due to at least two factors: 1) Aphaenogaster are significantly more likely to collect the ant-adapted seeds they discover than are ten other ant genera found in these forests and 2) the densities of Aphaenogaster and myrmecochorous plants are positively correlated at three nested spatial scales (within 20 x 20 m patches, among patches within a forest, and among 41 forests in the eastern United States). Although other ants can collect seeds, our analyses demonstrate that A. rudis is the primary seed dispersal vector for most of this rich temperate ant-dispersed flora. The low levels of plant partner diversity for myrmecochores demonstrated here rivals that of tropical ant-plants (myrmecophytes) and well exceeds that typically observed in temperate plant-frugivore and plant-pollinator mutualisms and myrmecochory in other biomes.

For animal-dispersed plants, evolutionary direction of seed traits is largely determined by the trait preference of disperser animals. Thus, clarifying conditions determining the disperser's preferences is important for understanding the evolution of dispersal traits in animal-dispersed plants. The intensity of the interference competition among dispersers may be a factor affecting the seed trait preference of disperser animals, because it often weakens the food preference of various animals. To test this possibility, we examined correlation between the intensity of interference competition among disperser ants and their trait preference for seeds of an ant-dispersed sedge, Carex tristachya Thunb. (Cyperaceae). By a cafeteria experiment conducted in the field, we first confirmed the overall preference by disperser ants for the elaiosome, which is a seed appendage facilitating the dispersal by ants. Second, we detected the negative correlation between the preference for elaiosomes and the frequency of interference among ants at a depot. Third, we compared this trend between dominants and subordinates of ants and revealed that the negative correlation was seen only in dominant species. These results suggest that the intensity of interference competition and the variation in its effect on animal species at different social status play important roles for the evolution of seed traits via the modification of seed trait preference by disperser animals.

Post-dispersal seed predation is a key process determining the variability in seed survival in forests, where most seeds are handled by rodents. Seed predation is thought to affect seedling regeneration, colonization ability and spatial distribution of plants. Basic seed traits are the essential factors affecting rodent foraging preferences and thus seed survival and seedling recruitment. Many studies have discussed several seed traits and their effects upon seed predation by rodents. However, the results of those previous studies are usually equivocal, likely because few seed traits and/or plant species tend to be incorporated into these studies. In order to elucidate the relationships between seed predation and seed traits, we surveyed the predation of 48600 seeds in a natural pine forest, belonging to 30 species, for three consecutive years. The results demonstrated that: (i) seed size and seed coat hardness did not significantly affect seed predation; (ii) total phenolics had a negative effect upon seed predation; (iii) positive effects of nitrogen content upon seed predation were found. From our study, it seems that the better strategy to prevent heavy predation is for plants to produce seeds with higher total phenolics content rather than physical defenses (i.e. hard seed coat) or larger seeds. Additionally, rodent foraging preference may depend more on Nitrogen content than other nutrient content of seeds.

Workers of Aphaenogaster rudis collect seeds of many species of spring-flowering, perennial herbs. This is part of a seed-dispersal system (myrmecochory) for which benefits to plants are documented, but consequences to ants have not been quantified. To test the predictions that colony size or reproductive output will be enhanced as a consequence of ants collecting seeds, we conducted a field experiment in a forest near Gambier, Ohio, in June and July 1993. Experimental colonies receiving seeds of Sanguinaria canadensis (N = 24 colonies) had ∼3.5 times as many gynes as control colonies (N = 27). Only 25% of control colonies produced any gynes, whereas 65% of experimental colonies did so. Control colonies produced as many males as experimental colonies. Access to seeds shifted the mass and numerical investment ratio in colony reproductive output toward female bias but did not affect the number of workers or queen size. These data support the hypothesis that myrmecochory is a true mutualism. Additionally, the experiment indicates that resource levels influence investment ratios in reproductive ants.

Summary 1 This paper draws together geographical variation and various correlates of individual seed dispersal success to evaluate spatial variation in major determinants of seed removal rates of the myrmecochore Helleborus foetidus, whose ant assemblages and diaspores vary geographically. 2 We censused seed removal by ants directly from individual plants in 12 populations and four regions across the Iberian Peninsula, and measured the elaiosomed seed, plant fecundity, and the biotic and abiotic environment in the close vicinity of each plant. The relative effect of these three groups of variables on seed removal was then modelled at each region using structural equation models and path analyses. 3 We found a pervasive effect of the close surroundings of each plant on dispersal. We also found a geographically variable influence of diaspore traits on dispersal. Such variable influence of the diaspore was closely related to the compositional and functional variation in ant guilds. 4 Synthesis: The appearance of an effect of diaspore and plant traits on dispersal depended on the surroundings of the plant, the identity of the ant visitors and ant abundance. This dependence itself might lead to different directions of selection among populations, a conclusion that has not emerged from seed offerings to ants, which is the usual protocol in myrmecochory research.

This paper reviews the current knowledge on weed seed movement in an agricultural environment. Seed movement is analyzed both from an agronomic and ecological perspective, focusing predominantly on horizontal seed movement. Abiotic (anemochory and hydrochory), as well as biotic (autochory, myrmecochory, epizoochory, and endozoochory) weed seed dispersal typologies are examined, highlighting the mechanisms involved, the specializations displayed by weed species that have evolved by exploiting a particular dispersal mechanism, and their adaptive interaction with the surrounding ecosystem. Emphasis is also placed on the crucial role of human activity (anthropochory), which can affect natural (biotic and abiotic) weed seed dispersal at several stages, partly via the worldwide commercial seed trade but, above all, by crop management operations, thereby potentially facilitating the entry and spread of alien weed species. This phenomenon, together with the invasive expansion of existing weeds that more successfully coevolve and adapt to the new environment, might exert an adverse effect on biodiversity. In-depth knowledge of weed seed dispersal, survival, and germination mechanisms is therefore essential for effective and eco-compatible management of the weed phytocoenoses present in the agroecosystem in order to promote a rational trade-off between agricultural productivity and environmental protection.

The modes of seed dispersal in the prostrate annual, Chamaesyce maculata, with multiple overlapping generations were investigated. We found that C. maculata has two modes of seed dispersal; autochory in the summer and myrmecochory in the autumn. Seasonally different modes of seed dispersal have not been known in other plant species. The large proportion of seeds produced in the summer was positioned further than the expanse of the parent plants by automatic mechanical seed dispersal. Therefore, autochory would be effective for avoiding competition between parent and offspring plants. No autochory occurred in the seeds produced in the autumn. The seeds of C. maculata without an elaiosome were dispersed by seed-collecting ants in the autumn. Although 18 ant species in total visited the plants of C. maculata at the 50 sites investigated, only two ant species, Tetramorium tsushimae and Pheidole noda frequently carried the seeds of C. maculata. The low frequency of seeds carried out of the nest by P. noda suggests that the workers of P. noda carry the seeds as food into their nest. So, P. noda might be a less effective seed disperser for C. maculata, corresponding to the effectiveness of seed dispersal by harvester ants. However, T. tsushimae ants frequently carried the seeds into and out of their nest, suggesting that T. tsushimae do not regard the seeds of C. maculata as a food resource. Thus, T. tsushimae may be an effective seed disperser for C. maculata.

The life-history characteristics and demography of Erythronium japonicum Decne. (Liliaceae) are described here. This is a typical prevernal species of temperate broad-leaved deciduous forests in the Japanese Islands and adjacent Far East regions, and is one of the representative perennials of Arcto-Tertiary origin. It flushes in early to late April (in May at higher elevations) on the deciduous forest floor in the lowlands to lower montane zone in Hokkaido, Honshu, Shikoku and Kyushu. Flowering individuals bear a single but showy large purplish-red flower, blooming downward from the top of the scape. This species is a typical polycarpic perennial and bumblebee-pollinated outbreeder, with pollen/ovule ratios of 4800–6150, although occasional inbreeding is known in the northern populations of Hokkaido. Yellowish-brown seeds, 2–3 mm long, with a tiny elaiosome, are susceptible to ant-dispersal (i.e. myrmecochory). According to our long-term monitoring study that has continued for the past 25 years, since 1979, its mean life expectancy is extremely long (approximately 40 years).

Dispersal morphology based on the myrmecochorous adaptations for predator avoidance of sevenCorydalis species including two varieties are investigated in southern Japan. Three types of myrmecochory were distinguished: myrmecochory with autochory (diplochory), the explosive ejection of seeds followed by ant transportation; myrmecochory with vegetative reproduction, seed-transportation by ants and reproduction by tuber; and pure myrmecochory, seed-transporting by ants only. Diplochory occurs in one winter annual plant, which has explosive capsules, a smooth seed surface, a small elaiosome, long pedicels and large bracts. Myrmecochory with vegetative reproduction occurs in two perennials that reproduce by tuber, although they also produce a small number of seeds with a medium-sized elaiosome. the pedicels and bracts are medium in size. Pure myrmecochory occurs in five annuals or biennials that are characterized by a rough seed surface with a large elaiosome, comparatively high seed production, short pedicels and only small bracts. Diplochory is exhibited by only one species distributed widely throughout Japan. Myrmecochory with vegetative reproduction is exhibited by species mainly distributed in cool-temperate northern Japan, while true myrmecochory is exhibited by the majority ofCorydalis species in warm-temperate Japan.

Successful species interactions require that both partners share a similar cue. For many species, spring warming acts as a shared signal to synchronize mutualist behaviors. Spring flowering plants and the ants that disperse their seeds respond to warming temperatures so that ants forage when plants drop seeds. However, where warm-adapted ants replace cold-adapted ants, changes in this timing might leave early seeds stranded without a disperser. We investigate plant seed dispersal south and north of a distinct boundary between warm- and cold-adapted ants to determine if changes in the ant species influence local plant dispersal. The warm-adapted ants forage much later than the cold-adapted ants, and so we first assess natural populations of early and late blooming plants. We then transplant these plants south and north of the ant boundary to test whether distinct ant climate requirements disrupt the ant-plant mutualism. Whereas the early blooming plant's inability to synchronize with the warm-adapted ant leaves its populations clumped and patchy and its seedlings clustered around the parents in natural populations, when transplanted into the range of the cold-adapted ant, effective seed dispersal recovers. In contrast, the mutualism persists for the later blooming plant regardless of location because it sets seed later in spring when both warm- and cold-adapted ant species forage, resulting in effective seed dispersal. These results indicate that the climate response of species interactions, not just the species themselves, is integral in understanding ecological responses to a changing climate. Data linking phenological synchrony and dispersal are rare, and these results suggest a viable mechanism by which a species' range is limited more by biotic than abiotic interactions - despite the general assumption that biotic influences are buried within larger climate drivers. These results show that biotic partner can be as fundamental a niche requirement as abiotic resources.

Summary This account presents information on all aspects of the biology of Pulmonaria officinalis L. (Common Lungwort) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characteristics, herbivores and disease, history and conservation. Pulmonaria officinalis is a distylous, perennial rosette hemicryptophyte that is naturalized in Britain. It occurs predominantly in the understory of broadleaved, mixed, open woods rich in hornbeam, beech and oak, but is has also been recorded from hedges, banks alongside streams, (sunken) roadsides, built-up areas, gardens, rubbish tips, yew woodland and, less frequently, coniferous woodland. Its native range stretches from southern Sweden, in the north, to northern Italy, in the south, and from western Germany to Poland and Lithuania. It is most common in central Europe. Pulmonaria officinalis reproduces both by sexual and vegetative means. The underground parts consist of a slowly creeping rhizome with adventitious roots. Despite the presence of an elaiosome that is attractive to ants that likely facilitates seed dispersal, populations often show a significant fine-scale spatial genetic structure and small neighbourhood sizes. The leaves and flowering stalks are covered in hairs of varied length and stiffness, and stems and inflorescences are sparsely covered with glandular hairs. Flowers of P. officinalis are heterostylous, with distinct pin and thrum morphs. The corolla varies from purple, violet or blue to shades of pink and red, or sometimes white. The flowers are mainly pollinated by solitary bees and bumblebees. Pulmonaria officinalis has significantly expanded its distribution in the British Isles since the 18th century, especially in southern England. P. officinalis is currently not regarded as threatened in Europe. Nonetheless, small, isolated populations of the species often show reduced reproductive success and lower genetic diversity, potentially affecting their long-term survival. Preservation of local habitat conditions by regular opening of the forest canopy and restoration of gene flow among populations are required to maintain viable populations of P. officinalis in the long term.

Aim We estimated the patterns of seed deposition provided by the eyed lizard, Timon lepidus, and evaluated whether these patterns can be generalized across plant species with different traits (fruit and seed size) and spatial distributions. Location Monteagudo Island, Atlantic Islands National Park (north-western Spain). Methods We radio-tracked seven lizards for 14 days and estimated their home ranges using fixed kernels. We also geo-referenced all fruit-bearing individuals of four plant species dispersed by eyed lizards in the study area (Corema album, Osyris alba, Rubus ulmifolius and Tamus communis), measured the passage time of their seeds through the lizard gut, and estimated seed predation in four habitats (bare sand, grassland, shrub and gorse). Seed dispersal kernels were estimated using a combination of these data and were combined with seed predation probability maps to incorporate post-dispersal seed fate (‘seed survival kernels’). Results Median seed gut-passage times were around 52–98 h, with maximum values up to 250 h. Lizards achieved maximum displacement in their home ranges within 24–48 h. Seed predation was high (80–100% of seeds in 2 months), particularly under Corema shrub and gorse. Seed dispersal kernels showed a common pattern, with two areas of preferential seed deposition, but the importance of these varied among plant species. Interspecific differences among dispersal kernels were strongly reduced by post-dispersal seed predation; hence, seed survival kernels of the different plant species showed high auto- and pairwise-correlations at small distances (

Myrmecochores are plant species that bear seeds with food-bodies adapting them for dispersal by ants. Within Australia and South Africa, myrmecochores account for a large percentage of the flora in sclerophyll vegetation on very infertile soils. On fertile soils, there are few myrmecochores and more species with fleshy fruits adapted for dispersal by vertebrates. This effect of very infertile soils may also account for the high incidence of myrmecochores in the floras of Australia and South Africa compared with other continents. The taxonomic distribution of myrmecochory shows it has evolved many times within the Australian flora. Evidence has been collected in relation to eight hypotheses that might account for the prevalence of myrmecochory on very infertile soils: (1) Myrmecochore seeds do not appear to be relocated to nutrient-enriched microsites. Seed-removing ant species relocate their nest entrances frequently; active ant nests are not nutrient-enriched; and seedlings emerging after fire are not located in nutrient-enriched soil. (2) Traffic of seed-removing ants is not greater on infertile than on fertile soils. (3) Burial to avoid predation by small mammals is not a significant factor for seeds in Australian vegetation. (4) Experiments in which diaspore traits are manipulated support the idea that a larger food body increases the likelihood that a diaspore will be taken by a seed-disperser ant species that will not eat the embryo, rather than by a seed-predator ant. However, evidence so far does not support the hypothesis that, on very infertile soils, seed-disperser ants are consistently more available than seed-predator ants. (5) Removal rates of fruits adapted for dispersal by vertebrates were, on average, two and a half times greater in vegetation on fertile soils. Birds were the main removers. Our current opinion is that the fruit-removing bird assemblage is more likely to be a consequence of the high incidence of species with vertebrate-adapted fruits, rather than the reverse. (6) Fleshy fruits are more expensive in potassium than food bodies for ants, but not in nitrogen or phosphorus. This might be a reason why fleshy fruits are uneconomic on very infertile soils. (7) Species with smaller embryo-plus-endosperm weight are relatively more likely to be adapted for dispersal by ants rather than vertebrates. However, differences in the frequency distribution of embryo-plus-endosperm weights between infertile and fertile soils are moderate in the Sydney area. An indirect association between soil fertility and dispersal mode via embryo-plus-endosperm weight cannot account for much of the difference in dispersal spectrum. (8) Species growing to less than 2 m tall are relatively more likely to be adapted for dispersal by ants rather than vertebrates, and also account for more of the flora on infertile than on fertile soils. This indirect correlation is capable of accounting for as much as 80% of the higher incidence of myrmecochory on infertile soils.

Ants are effective at moving seeds toward their nests, something that may benefit the seeds. We evaluated whether seed movements that may be useful for the rehabilitation of degraded pastures in Colombia can be enhanced by local ants. An artificial aril was prepared and then evaluated in six open cattle pasture farms. Twenty paper disks (each holding seeds with an artificial aril, honey, tuna oil, and control) were set up along linear transects at each farm, and monitored five times in 48 hours. A total of 340 out of 480 seeds were moved from the experimental units by ants. Seeds with tuna oil and an artificial aril were removed twice as frequently as the control and honey smeared seeds. Ectatomma ruidum, Solenopsis geminata, and Pheidole sp. removed the majority of seeds. Advantages of the artificial aril over tuna oil are discussed. This inexpensive technique can enhance seed movement by generalist ants in degraded pastures, likely contributing to regeneration and ecological rehabilitation.

Summary Ants can play an important role in the success and impact of many species invasions, including weed species. This study, in a fragment of secondary forest in Vicosa, Minas Gerais State, Brazil, evaluates the role of native leafcutter ants in the spread of the exotic plant Murraya paniculata, an alternative host of bacteria causing citrus greening disease. The foraging activity of leafcutter ants on fruits of ten M. paniculata plants was observed daily during August 2010. The only leafcutter ant species observed was Acromyrmex niger (Smith, 1858) (Hymenoptera: Formicidae), which showed a preference to remove M. paniculata fruits to its nests, cleaning them and discarding the seeds on refuse piles afterwards. Murraya paniculata was the main plant whose seeds were deposited in refuse piles (61-82% of the seeds), where they commonly germinated. This study shows that dispersal of this weed is facilitated by native leafcutter ants. This may promote the spread and establishment of this alternative host of citrus greening disease and so lead to problems in monitoring and control of this disease.

Seeds are often carried by omnivorous ants even if they do not carry elaiosomes. Although many seeds carried by ants are consumed, both seeds abandoned during the seed carrying and leftover seeds are consequently dispersed (dyszoochory). These non-myrmecochorous seeds do not necessarily attract ants quickly. Therefore, these seeds often seem to be exposed to the danger of consumption by pre-dispersal seed predators. We propose the hypotheses, “seed predator deterrence hypothesis” that plants may benefit from seed-carrying ants if they deter seed predators from visiting plants, and seed-carrying ants may play additional roles in plant reproductive success, besides dyszoochory by ants. To test the hypotheses, we investigated the abundance of seed-carrying ants of the species Tetramorium tsushimae Linnaeus and Pheidole noda Smith F., and of the seed predatory stinkbug, Nysius plebeius Distat, on the spotted sandmat, Chamaesyce maculata L. Small, of which the seeds have no elaiosomes but are consumed by both ants and bugs. In the field, ants and stinkbugs seldom encountered each other on the plant. The number of stinkbugs beneath the plants with ants was smaller than that beneath the plants without ants. In laboratory experiments, the number of stinkbugs on the shoot was smaller when ants were present than when they were absent. These results might support the seed predator deterrence hypothesis: the probability of seed predation by stinkbugs seems to be reduced by the ant visits on plants and/or the existence of ants beneath the plants. This study highlights a new ant–plant interaction in seed dispersal by ants.

Summary 1. The dispersal capabilities of most plant species remain unknown. However, gaining basic dispersal information is a critical step for understanding species’ geographical distributions and for predicting the likely impacts of future climate change. Dispersal mechanisms can indicate short- or long-distance dispersers, and highlight important biological interactions. 2. To predict dispersal mechanisms for species where information is limited, we used generalized linear mixed models with basic life-history and ecological traits. Sets of models were created (using Australian species) for six dispersal categories: wind, unassisted, water, ant, vertebrate-ingestion and vertebrate-attachment dispersal mechanisms. We validated our models on the dispersal mechanisms of 50 Australian, 30 Californian, 30 Swiss plant species and a global compilation of 70 species. 3. Growth form, seed mass and vegetation type were the main predictor variables. Our models predicted dispersal mechanisms for Australian and Californian plant species equally well (c. 70% correct) and to a lesser extent for the Swiss flora (c. 50% correct). Our models predicted observed dispersal mechanisms (c. 50% correct) equally well to inferred dispersal mechanisms (based on seed morphology). 4. Synthesis. Our approach of using easily obtainable traits for predicting dispersal mechanisms of species allows dispersal information to be predicted for species where little is known. From here, the application of realistic dispersal curves to the predicted dispersal mechanisms will further understanding on the dispersal capabilities of species.

Summary 1. A substantial portion of the crop of fruiting trees falls beneath parent plants as a result of dispersal failure. Such diaspores are considered as waste because the likelihood of plant recruitment is usually very small close to parent trees. However, many animals may rescue fallen diaspores and provide them with another chance of dispersal and establishment. 2. We investigated the effectiveness of two broad types of seed dispersal vectors for the regeneration of Xylopia aromatica in the Brazilian cerrado savanna: birds that remove diaspores from plant canopies and ants that harvest diaspores on the ground under the parent plant (as rescuers) or from bird feces (as secondary dispersers). 3. Birds removed a mean of 32% of the crop from plant canopies, but removal was independent of crop size. A large part of the crop (mean of 25%) landed beneath parent plants or was dropped after manipulation by vertebrate frugivores as viable diaspores. Ants from at least five genera removed most fallen diaspores (up to 83%) within 24 h. Ants influenced the fate of a large amount of the crop, and for some trees ants removed as many diaspores as birds. 4. Large ants rescued some diaspores to distances beyond the parent plant crown, but birds may remove diaspores 40-fold farther. However, seedlings of X. aromatica were only found close to nests of large ants, probably due to diaspore rescuing and ⁄ or directed secondary dispersal by certain ant groups following primary dispersal by birds. Although an unknown percentage of seeds was lost to granivorous ants, diaspore removal by ants potentially enhances the likelihood of plant recruitment due to distance-related benefits and directed dispersal to ant nests, while birds play a premier role in long-distance seed dispersal and metapopulation dynamics. 5. Synthesis. Birds and ants provide complementary seed dispersal at different spatial scales to X. aromatica. Since ants remove most fallen diaspores beneath parent plants, the use of diaspore removal rates from plant canopy as a surrogate of plant fitness may be misleading. By acting as secondary dispersers, ants may also provide a fine-tuned dispersal following long-distance dispersal by birds (i.e. diplochory).

Most obligate seeder species build up a soil seed bank that is associated with massive seed germination in the year immediately after a fire. These species are also shade-intolerant and disappear when vegetation cover closes, creating unsuitable conditions for seedling recruitment. The only way for these plants to expand their populations is when habitats suitable for seedling recruitment arise (i.e. in years immediately after a fire). However, short primary seed dispersal of obligate seeders does not allow these plants to colonise the suitable habitats, and these habitats can only be colonised by secondary seed dispersion. We hypothesised that Fumana ericoides, an obligate-seeding small shrub, not only establishes abundantly in the first year after fire, but also expands its local range in the following years due to secondary dispersal by ants while suitable habitats are still available. We tested this hypothesis using experimental studies and a simulation model of potential population expansion in a recently burned area. Results showed that F. ericoides not only established prolifically in the year immediately after fire, but was also able to recruit new individuals and expand its population in the years following the fire, despite a low germination rate and short primary seed dispersal. Ant-mediated seed dispersal and availability of suitable habitats were key factors in this phenomenon: ants redistributed seeds in suitable habitats while they were available, which accelerated the expansion of F. ericoides because new plants established far away from the core population.

Questions: Is the red fox a potential vector for epizoochorous seed dispersal? Can seed attachment and retention be predicted from plant and seed traits? Location: Grasslands in southern Norway. Methods: Epizoochorous seed attachment on the red fox was studied by walking a dummy fox through the vegetation and comparing seeds found on the dummy with the estimated seed availability in the vegetation. Seed retention, i.e. the ability of different seeds to stay on the fox, was estimated in a separate experiment. Seed attachment and retention were related to plant and seed traits using statistical models that account for heteroscedasticity and zero-inflated data. Results: The majority of seeds attached to the fox originated from a few species, but also species without specific seed traits that are supposed to enhance epizoochory attached at least some seeds to the fox. The probability of seed attachment was positively related to plant height, bristle and hooked seed appendages, and negatively related to winged appendages, seed mass, and seed sphericity. Seed retention was positively related to the seed traits bristles, hooks and pappus. For several species, the results indicate a high potential for dispersal over long distances. Conclusions: In modern agricultural landscapes, large herbivores are often restricted in their mobility or are found at low densities, and other animal vectors may therefore be important for seed dispersal. In our study, a range of plant species were able to disperse by attaching seeds to, and having their seeds retained in, the fox fur some distance. We suggest that the red fox may be an important vector for epizoochorous seed dispersal in the agricultural landscape.

To elucidate roles of an omnivorous ant, Tetramorium tsushimae Emery, against pre-dispersal seed consumers in the seed dispersal of Chamaesyce maculata (L.) Small, the effects of the seed injury by a stinkbug, Nysius plebeius Distat, on the seed removal by the ant and the germination rate were examined in laboratory experiments. The ants of T. tsushimae removed more frequently non-injured seeds than injured seeds. Therefore, low removal frequency of injured seeds by T. tsushimae ants might facilitate the increase in removal frequency of non-injured seeds, consequently leading to efficient seed dispersal of C. maculata. The germination rate of injured seeds that N. plebeius nymphs sucked was conspicuously lower than the non-injured seeds. The germination rate of seeds that T. tsushimae ants carried out of their nest was similar to that of the non-injured seeds. Thus, seed removal by T. tsushimae ants has hardly effects on the germination of these seeds. Therefore, the preferential removal of non-injured seeds by T. tsushimae ants might contribute to the dispersal success of C. maculata seeds. These results might show a novel interaction between myrmecochorous plants and ants in which the assessment of seed quality by ants contributes to the reproductive success of plants.

Studies on embryology and seed morphology are complementary to molecular phylogenetics and of special value at the genus level. This paper discusses the delimitation and evolutionary relationships of genera within the tribe Hydrophylleae of the Boraginaceae. The seven Nemophila species characterized by a conspicuous seed appendage are similar in embryology and seed structure. The ovule is tenuinucellate and unitegmic with a meristematic tapetum. The embryo sac penetrating the nucellar apex is of the Polygonum type, has short-lived antipodal cells, and an embryo sac haustorium. The endosperm is cellular, producing two terminal endosperm haustoria, of which the chalazal has a lateral branch. Embryogeny is of the Chenopodiad type (as in Pholistoma). The seed coat is formed from the small-celled inner epidermis of the integument. The large-celled outer epidermis of the integument disintegrates into scattered cells. Seed pits evolve from irregularly placed inner epidermal cells of the integument. The chalazal part of the ovule produces a cucullus, that functions as an ant-attracting elaiosome. Those species of Nemophila with a conspicuous cucullus form a natural genus. Nemophila is most closely related to Pholistoma. The integumentary seed pits of Nemophila might have evolved from ovular seed pits similar to those in Pholistoma.

The mound building ant Formica exsecta Nyl. is widely distributed in grassland ecosystems of the Central European Alps. We studied the impact of these ants on seed bank and vegetation patterns in a 11 ha subalpine grassland, where we counted over 700 active ant mounds. The mounds showed a distinct spatial distribution with most of them being located in tall-grass, which was rarely visited by ungulates (red deer; Cervus elaphus L.). Heavily grazed short-grass, in contrast, seemed to be completely avoided by ants as only few mounds were found in this vegetation type. The species composition of the ant mound and grassland seed banks was quite similar, i.e. from 15 common plant species 12 were found in both seed bank types. We found the same proportions of myrmecochorous seeds in ant mound and grassland soil samples. In contrast, the number of seeds was 15 times higher in mound compared with the grassland soil samples. Also, the vegetation growing on ant mounds significantly differed from the vegetation outside the mounds: graminoids dominated on ant mounds, herbaceous and myrmecochorous species in the grassland vegetation. We found significant continuous changes in vegetation composition on gradients from the ant mound centre to 1 m away from the mound edge. Overall, F. exsecta was found to have a considerable impact on seed bank and vegetation patterns in the grassland ecosystem studied. These insects not only altered grassland characteristics in the close surrounding of their mounds, but also seem to affect the entire ecosystem including, for example, the spatial use of the grassland by red deer.

Summary 1 This account reviews information on all aspects of the biology of Mercurialis perennis that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. 2 Mercurialis perennis is a dioecious, clonal, perennial forb of woodland, hedgerows, limestone pavement, screes and tall-herb communities. It is very tolerant of low light; it can also grow in unshaded conditions, although higher light flux densities result in lower shoot biomass. It is Eurocaucasic, occurring throughout temperate areas of Europe as far east as the Russian border. 3 Mercurialis perennis occurs on a wide variety of soil types over a pH range from 4.3 to 8.5, although it is most abundant on more base-rich clay or loam soils with a low organic content. It seldom occurs on peat or very sandy soils. It can grow in soils with low availability of macronutrients but it responds positively to nutrient addition from atmospheric or agricultural sources. It is intolerant of waterlogging, mainly because of poor aerenchyma development; its limited capacity to oxygenate the root environment can lead to ferrous ion toxicity. The resulting superficial root development on heavy soils may confer drought susceptibility in summer. 4 Mercurialis perennis is predominantly wind-pollinated. Ants are the main dispersal agents and the seed bears an elaiosome which offers them a lipid-rich reward. Establishment from seed is uncommon and vegetative propagation is the main means of expansion, often leading to dense clonal stands of aerial shoots. 5 Mercurialis perennis has been described as a stress-tolerant competitor. The persistence of its clones and slow dispersal have led to it being regarded an as indicator of ancient, semi-natural woodland.

Australia, the flattest, driest, and geologically oldest vegetated continent, has a uniquely high proportion of nutrient-poor soils. We develop a "Nutrient-Poverty/Intense-Fire Theory," which postulates that most anomalous features of organisms and ecosystems of Australia are the evolutionary consequences of adaptations to nutrient poverty, compounded by intense fire that tends to occur as a result of nutrient poverty. The fundamental tenet of the theory is that plants growing in environments with plentiful light and periodic adequate moisture, but on soils poor in phosphorus, zinc, and other indispensible nutrients, can synthesize carbohydrates in excess of the amount that can be combined with, or catalyzed by, these nutrients for metabolism and production of nutrient-rich foliage and reproductive tissues. They use this "expendable energy" to produce well-defended foliage, large quantities of lignified tissues, and readily digestible exudates. Rapid accumulation of nutrient-poor biomass, a result of low rates of herbivory, provides fuel for intense fire. Intense fire exacerbates nutrient poverty by volatilizing certain micronutrients critical for animals. Anomalous features of organisms of Australia that can be explained by this theory, rather than by climate or phylogenetic history alone, include the following: most woody plants have long-lived, durable foliage; plants defend their tissues primarily with carbon-rich but nutrient-poor compounds; an unusually high proportion of plants protects seeds from fire and granivores in sturdy, woody capsules or follicles; plants allocate unusually large amounts of expendable energy to production of carbon-based exudates, such as nectar and gums; an unusually high proportion of plant species is pollinated by vertebrates that average larger size than pollinators on other continents; herbivores are small and have slow metabolism; there are no ruminants, mammals that eat mainly subterranean plant matter, or fungus-culturing termites and ants; vegetation dominated by leaf-spinescent plants is more extensive than vegetation dominated by stem-spinescent plants; nitrogen-fixing plants are major components of most vegetation types; there is a higher proportion of myrmecochorous plant species than on any other continent; there are hardly any stem-succulent and few leaf-succulent, perennial, non-halophytic plant species; and an unusually high proportion of bird species breeds cooperatively. Although the Nutrient-Poverty/Intense-Fire Theory can provide plausible explanations for these anomalous features, some puzzles remain, among them the great success of introduced herbivores, the lack of grazers on extensive grasslands on cracking clays, the apparently low productivity of ants, and the prominence of the parasitic plants of Australia. By examining the ratios of available energy to nutrients, particularly scarce nutrients, ecologists may identify processes not previously recognized as important for life forms or biotic adaptation on other continents.

Hunting can change abundances of vertebrate seed predators and seed dispersers, causing species-specific changes in seed dispersal and seed predation and altering seedling communities. What are the consequences of these changes for the adult plant community in the next generation and beyond? Here, I derive equations showing how reduced seed dispersal reduces plant reproduction by intensifying kin competition, increasing vulnerability to natural enemies, and reducing the proportion of seeds passing through disperser guts. I parameterize these equations with available empirical data to estimate the likely effects on next-generation abundances. I then consider the indirect effects and longer-term feedbacks of changed seed or adult abundances on reproductive rates due to density-dependent interactions with natural enemies and mutualists, as well as niche differentiation with competitors, and discuss their likely qualitative effects. The factors limiting seed disperser and seed predator populations in natural and hunted forests emerge as critical for determining the long-term effects of hunting on rates of seed dispersal and seed predation. For example, where seed dispersers are held to a constant abundance by hunters, decreases in the availability of their preferred food plants are expected to lead to increased per-seed dispersal probabilities, potentially to the point of compensating for the initial disperser decline. I close by discussing the likely reversibility of hunting-induced changes in tropical forests and key questions and directions for future research.

Myrmecochores are plants with seeds adapted for ant dispersal. This specialized dispersal syndrome may provide Erythronium americanum seeds with protection from predators within the eastern deciduous forests. To determine the adaptive significance of myrmecochory in E. americanum, seed removal rates and seed predation in relation to seed release date and location along the Potomac River in Langley, Virginia, were examined. The number of seeds removed from four exclosure treatments were monitored two times in 1992 and three times in 1993 within floodplain and hilltop populations of E. americanum. Overall, seed removal was greatest from control depots, and E. americanum seeds were removed at nearly the same rate from predator-exclusion depots, indicating that removal from open depots is largely due to ant removal. Ants removed significantly more seeds than predators in the first 48 h of seed exposure and could potentially remove all E. americanum seeds before nightfall. Aphaenogaster rudis was identified as the primary disperser of E. americanum. Seeds placed in depots after the natural seed release period were discovered more quickly and removed by ants at a significantly higher rate than seeds released at the natural date. These results suggest that ant dispersal of E. americanum seeds reduces the likelihood of seed predation.

Measuring the fate of seeds between seed production and seedling establishment is critical in understanding mechanisms of recruitment limitation of plants. We examined seed fates to better understand the recruitment dynamics of four resprouting shrubs from two families (Fabaceae and Epacridaceae) in temperate grassy woodlands. We tested whether: (i) pre-dispersal seed predation affected seed rain; (ii) post-dispersal seed predation limited seed bank accumulation; (iii) the size of the seed bank was related to seed size; and (iv) viable seeds accumulated in the soil after seed rain. There was a distinct difference in seed production per plant between plant families with the legumes producing significantly more seeds per individual than the epacrids. Seed viability ranged from 43% to 81% and all viable had seed or fruit coat dormancy broken by heat or scarification. Pre- dispersal predation by Lepidopteran larvae removed a large proportion of seed from the legume seed rain but not the epacrids. Four species of ants (Notoncus ectatomoides, Pheidole sp., Rhytidoponera tasmaniensis and Iridomyrmex purpureus) were major post-dispersal seed removers. Overall, a greater percentage of Hardenbergia (38%) and Pultenaea (59%) seeds were removed than the fleshy fruits of Lissanthe (14%) or Melichrus (0%). Seed bank sizes were small (

1 Despite three decades of intensive research on seed predation, rather little is known about how important a role it plays in plant demography. Here a balance sheet of seed predation is drawn up for Pinus sylvestris, based on mortality caused by its main seed predators. This species is of special interest because trees carry seeds throughout the year and can therefore support specialist as well as generalist seed predators. Also, its regeneration in Scotland is weak and some of its main seed predators (red squirrels, crossbills, wood ants) are themselves threatened. 2 Field data from two P. sylvestris forests were used to estimate rates of predation on seeds due to pre- and post-dispersal predators, including both specialists and generalists. The rates of predation changed systematically over time and were fitted to time-dependent functions. The resulting functions were incorporated into a model, which was solved numerically to determine the fate of a cohort of seeds. 3 On average, approximately 20% of seeds in the cohort were consumed by pre-dispersal seed predators, approximately 25% of seeds by post-dispersal seed predators, and approximately 55% of seeds were still alive at the end of 2 years. This reduces the seed pool for regeneration of P. sylvestris, but is unlikely to be a serious problem for regeneration. 4 Seed survival was most sensitive to the rate at which seeds became invulnerable to further seed predation, and to the rate of seed dispersal from cones on trees. Seed survival was less sensitive to seed predation. However, among seed predators, carabids feeding on loose seeds and birds eating seeds in open cones were the most important. 5 Cones open as they dry out, and the timing of seed dispersal is therefore weather-dependent. Late opening of cones had a deleterious effect on seed survival because it led to an increase in pre-dispersal seed predation. Thus, in a period of climate change, patterns of seed predation would be expected also to change, altering the success of regeneration.

Life-history characteristics and demography of Trillium tschonoskii (Trilliaceae) were studied and are described here. Trillium tschonoskii is the most wide-ranging species among Asiatic Trillium , ranging from southern Sakhalin, the Japanese Islands (excepting Kyushu) to the Korean Peninsula, Taiwan and further to inland China and the Himalayas. The ecological range of T. tschonoskii is broad, extending from lowland forests to montane and further to subalpine mixed forests consisting of conifers and subalpine birch, Betula ermani . This species is a typical polycarpic perennial, similar to all other Japanese Trillium species, and flowers in early to late April in lowland populations and in midJune to early July in subalpine habitats. Trillium tschonoskii typically has three white petals and three sepals, and its pollinators are diverse, for example, flies, beetles and bees such as Scatophagiae (Diptera), Oedemera lucidicollis (Coleoptera) and Andrena sp. (Hymenoptera). Pollen/ovule ratios of T. tschonoskii are approximately 700, thus T. tschonoskii is potentially an inbreeder. Seed outputs per plant are variable, 29–190 (mean 85.0) in 1980, and 28–168 (mean 79.8) in 1984. Seeds with a large soft juicy elaiosome attract ants, which are effective dispersal agents, but nocturnal elaiosome predators, mainly ground beetles, are also very active. Our long-term observations indicate that it takes approximately 10 years to reach a sexually mature stage and the life expectancy of mature plants is assumed to be exceedingly long, extending over 40 years.

Seed predation, an omnipresent phenomenon in tropical rain forests, is an important determinant of plant recruitment and forest regeneration. Although seed predation destroys large amounts of the seed crop of numerous tropical species, in many cases individual seed damage is only partial. The extent to which partial seed predation affects the recruitment of new individuals in the population depends on the type and magnitude of alteration of the germination behavior of the damaged seeds. We analyzed the germination dynamics of 11 tropical woody species subject to increasing levels of simulated seed predation (0–10% seed mass removal). Germination response to seed damage varied considerably among species but could be grouped into four distinct types: (1) complete inability to germinate under damage ≥1%, (2) no effect on germination dynamics, (3) reduced germination with increasing damage, and (4) reduced final germination but faster germination with increasing damage. We conclude that partial seed predation is often nonlethal and argue that different responses to predation may represent different proximal mechanisms for coping with partial damage, with potential to shape, in the long run, morphological and physiological adaptations in tropical, large-seeded species.

Long-distance dispersal of seeds is an important process in metapopulation dynamics and in plant migrations, but at the same time extremely difficult to observe or quantify directly. If seed dispersal ability were related to attributes of seeds or motherplants, long-distance seed dispersal would be predictable by indirect approximation using easy-to-measure traits. Seed size has been suggested to be such a key trait in seed dispersal ability. However, having smaller seeds also implies having more numerous seeds per plant individual (given equal reproductive effort), and consequently increases the probability of seeds being ingested accidentally. The question is whether small-seeded species are more abundant in herbivore dung because smaller seed size increases survival rate during gut passage or because they are produced (and ingested) in greater numbers than larger seeds. We investigated endozoochorous seed dispersal via cattle grazing a meadow, and related seed abundance in dung samples to seed attributes. We found that seeds were ingested and passed through the bovine intestinal tract in proportion to the numbers produced per unit area in the grazed vegetation. In contrast, no relationship could be found between endozoochorous dispersal potential (measured as abundance of seeds in dung samples corrected for seed output in the grazed vegetation) and seed attributes such as seed mass, seed shape (roundness), and thickness of the seed coat. This finding underlines the importance of seed number in plant dispersal ability. In addition, it shows that grazing mammals may constitute an important dispersal vector for many plant species conventionally classified as 'unspecialised'.

The life-history characteristics and demography of Trillium camschatcense (Trilliaceae) were studied and are described here. T. camschatcense, a typical polycarpic perennial, is a representative of the spring plants growing in temperate broad-leaved deciduous forests in the lowlands of Hokkaido and northern Honshu, and adjacent Far East regions. Flowering takes place in early to late April. T. camschatcense typically has three white petals and three sepals, is primarily pollinated by bumblebees (Bombus and Andrena spp.) and beetles (Carpophilus and Aphthonaltica spp.), with pollen/ovule ratios of 2200, and is a conditional outbreeder. Occasional inbreeders are also known in the north-eastern populations of Hokkaido. Capsules mature in late summer, late July to August. Light-brown seeds, 2–3 mm long, with a soft juicy elaiosome containing sugars such as fructose, glucose and saccharose attracts ants and beetles, but only ants are effective dispersal agents for Trillium seeds. Our long-term monitoring study has continued for 25 years from 1980 to 2004, and most of the flowering individuals turned out to be extremely long-lived, at ages of well over 20 years. Notably, frequent switches in growth stages occur, not only proceeding from the single-leaf sterile stage to the three-leaved sterile-stage but also reverting to earlier growth stages.

Many studies of postdispersal seed fate use seed removal as an index of seed predation. However, following primary seed dispersal, some seeds are transported intact by ants, dung beetles, scatter-hoarding animals, or abiotic processes to new microsites (secondary dispersal) where germination is possible. Despite a growing realization that secondary seed dispersal can play an important role in plant recruitment, many researchers continue to use seed removal as a proxy for seed predation and are focused too intently on only the initial step of seed fate. We describe, using examples from the recent literature, how the results of some seed removal studies may have been misinterpreted, present plausible, alternative explanations for the fate of seeds in those studies, and discuss the importance of detailed studies of seed fates. Following the fates of seeds can be difficult, but such studies contribute much more to our understanding of seed dynamics and plant fitness.

The services provided within a community can change as the species composition of that community changes. For example, ant–seed dispersal mutualisms can be disrupted in habitats dominated by invasive ants. We propose that this disruption is related to changes in mean ant body size, given that invasive ants are smaller than most native seed-dispersing ants. We demonstrate that the mean and maximum distances that ants transport seeds adapted for ant dispersal increase with worker body size, and that this relationship is an accelerating power function. This pattern is consistent among three ant subfamilies that include most seed-dispersing ants as well as most invasive ant species, is generalizable across ant species and communities, and is independent of diaspore mass. Using a case study, we demonstrate that both the mean body size of seed-collecting ants and seed dispersal distances are decreased in sites invaded by Solenopsis invicta, the imported red fire ant. Furthermore, we demonstrate that the mean si...

In moving seeds from one location to another, dispersers define the ecological context that a plant will experience throughout its lifetime. Because seed deposition sites may benefit one plant life cycle stage but not others, dispersal may give rise to a conflict between a plant's dispersal needs (e.g., predator escape) and its requirements for successful establishment (e.g., suitable habitat). In this study, we assessed the effects of two com- ponents of seed dispersal by ants (seed burial depth and elaiosome removal) at several stages during the recruitment of Leucospermum truncatulum, an ant-dispersed plant from the fynbos shrublands of South Africa. A seed-predator exclusion experiment revealed that the removal of elaiosomes significantly reduced rodent predation on seeds buried 1 cm deep and increased the viability of seeds that were not consumed. In contrast, we found that elaiosomes had no effect on the probability of a living seed emerging as a seedling. In a seed burial depth experiment in which predators were not excluded, deeper burial significantly enhanced seed survival, but this benefit came at the expense of reduced seedling emergence, delayed emergence, and smaller cotyledon size. Despite the potential importance of these seedling characteristics, elaiosomes and burial depth had no significant effect on seedling survival through the first year of this study. In contrast, burial depth had strong positive effects on the fraction of seeds that persisted in the seed bank. Although dormant individuals may die before germinating and reproducing, those that persist at greater soil depths can play a crucial role in rescuing populations from local extinction in unpredictable environments. Given the extreme variability in fire frequency in fynbos, the net effect of seed dispersal by ants on plant populations will depend on how temporal fluctuations in fire regimes influence cost-benefit thresholds related to seed dormancy and seed mortality.

We describe the role of leaf-litter ants (Pheidole spp.) in the seed bank dynamics of several small-seeded shrubs in a Costa Rican lowland rain forest. These ants harvest seeds from frugivore feces and cache them in their nests in partially decomposed twigs. Most harvested seeds are eaten but some are placed in viable condition on refuse piles. From 24 to 38% of the colonies (depending on ant species) contain cached seeds and 25-32% have seeds on refuse piles. Experiments with captive colonies of Pheidole nebulosa and P. nigricula demonstrated that - 6% of harvested Miconia nervosa and M. centrodesma seeds are deposited on refuse piles. Because seeds generally retain viability longer than the nest twig remains intact, harvested seeds are not trapped inside twigs. Experimental plant- ings of 4-d-old Miconia nervosa seedlings on two types of substrate (ant refuse pile vs. topsoil) under two light levels (equivalent to small and large clearings) demonstrated that seedlings grew faster and survived better on refuse piles under light levels typical of small clearings. Light levels typical of large gaps are not necessarily advantageous for establish- ment of understory rain forest plants. These results illustrate the dynamic nature of a tropical soil seed bank and the complexity of plant-animal interactions that occur there. Ants are simultaneously antagonistic and mutualistic towards seeds, killing most but significantly benefiting some. This interaction is extremely common (Pheidole density > 300 individuals/) and likely influences plant recruitment patterns. Our results challenge the generalizations that small seeds are largely protected from predation because of their size, that post-dispersal seed harvesting is equiv- alent to seed predation, that competition among seedlings from a frugivore defecation is common, and that small seeds accumulate over long periods of time in the seed bank. We hypothesize that differential harvesting and treatment of seeds by ant species may be a mechanism underlying community-level patterns of regeneration in small-seeded plants. Also, the incidental benefits to uneaten seeds deposited on refuse piles provide additional evidence that myrmecochory evolved in plants that strengthened rare but consistent benefits of being harvested by "granivorous" ants.

We studied influence of the Argentine ant's Linepithema humile occurrence on seed dispersal of Rhamnus alaternus (Rhamnaceae). Rhamnus alaternus is a fleshy fruit plant dispersed primarily by birds; the seeds have an elaiosome attractive to ants. The observations were made in two study plots of Mediterranean cork-oak forests (one invaded and the other not invaded by L. humile) over two years. For R. alaternus, presence of L. humile was associated with of the following: reduction of seed transport to ant nests (80.2% of seed offered were removed in non-invaded vs 7.1% in invaded area), a shorter seed dispersal distance (mean = 90.2 cm in non-invaded vs 1.1 cm in invaded area), increase in seed retention time on the soil surface (median time in non-invaded was 50 vs 209.2 min in invaded area) and increased vulnerability to predation. In addition there was lower probability of seedling emergence, due to little elaiosome removal from the seeds (82.0% of emergence for seeds without elaiosome and 57.3% for seeds with elaiosome) These results, similar to findings obtained in South African fynbos, confirm that the Argentine ant invasion can strongly affect ecosystem processes in the Mediterranean biome.