Endozoochorous Dispersal Research Articles

Red‐deer dung increases species diversity but does not influence species composition of open grasslands

AbstractQuestionsFree‐ranging herbivores are often seen as important endozoochorous dispersal vectors for plant propagules. Dispersal by free‐ranging animals, in contrast to domestic animals, and its effects on vegetation have rarely been studied. We ask what are the effects of deposition of dung on open landscape vegetation, how does it influence vegetation development after disturbance by soil removal, and does it change species richness or composition?LocationThe Doupov Mountains, Czech Republic.MethodsWe established a six‐year experiment in 2015 to study the effects of dung deposition on vegetation of an open grassland landscape. The experiment comprised 300 plots distributed across five fenced site locations and treatments were implemented in partially crossed design, with soil removed (disturbance) and dung pellets deposited; treatments were applied once to five replicates, from June to October 2015. We recorded plant species cover at the beginning of the vegetation seasons of 2016, 2017 and 2021.ResultsDung deposition increased species richness and Ellenberg Indicator Values for nutrients, and these effects were stronger in disturbed plots; however, these effects diminished with time. There were no effects of dung deposition on species composition. In contrast, disturbance affected species diversity, composition, Ellenberg Indicator Values for nutrients, proportion of dung‐dispersed species, but not species richness. Surprisingly, there were no effects of timing of dung deposition.ConclusionsOur results indicate that endozoochorous seed dispersal by red deer impacts vegetation dynamics of this open grassland landscape, but effects are weak and diminish with time. Considering the large seed load in dung, it is possible that endozoochorous seeds from wild herbivores are incorporated into the soil seed bank, where they persist until appropriate ecological conditions for germination arise.

Evidence that long‐distance dispersal of aquatic invertebrates by ducks increases with propagule size

AbstractMigratory ducks are key dispersal agents for aquatic organisms, yet differences in their potential for short‐ and long‐distance dispersal are still poorly understood, particularly differences among aquatic invertebrate taxa.Using seven species of aquatic invertebrates and a duck species known to feed on them in the wild (the northern shoveler) as a model system, we evaluated whether their potential for endozoochorous dispersal varies among five of the species and scales with propagule size for the seven species. We also tested the expectation of a lower dispersal potential for invertebrate propagules, as compared to plant seeds; and evaluated whether intra‐specific variation (in particular, sexual dimorphism) influences the potential of waterbirds as dispersal vectors.An experiment with five invertebrate species demonstrated that most resting eggs (68%–95%) were retrieved by 4 hr after ingestion, with maximum gut‐passage times ranging from 16 hr forDaphnia magnato 36 hr forArtemia salinaandThamnocephalus platyurus. Using models that combine migratory duck movements with gut‐passage times, we show that aquatic invertebrates may disperse frequently over distances of 15–16 km (median dispersal distance) and regularly over distances up to 110–166 km (Q99distance).Increasing propagule size resulted in increasing gut‐passage times, decreasing survival of gut passage and decreasing hatching success. While propagule size had no effects on “regular” dispersal distances (mean, median,Q95andQ99), the frequency of long‐distance dispersal increased with it.Increasing propagule size therefore had two contrasting effects on invertebrate dispersal potential, decreasing the frequency of dispersal (fewer seeds dispersed) but increasing the potential for long‐distance dispersal.Conclusions: We provide evidence that endozoochory of invertebrate propagules by waterbirds results in frequent dispersal among wetlands (tens of km) and regular dispersal at regional scale (over a hundred km).

The Potential for Endozoochorous Dispersal of Vachellia nilotica Seeds by Goats: Implications for Bush Encroachment

Seed dispersal has become an important component in understanding plant–animal interaction. Recently, there have been concerns about the role of ruminants, particularly browsers, in the dispersal of woody plant seeds. This study aimed to determine whether including Vachellia nilotica seeds in livestock, diets could reduce the spread of viable seeds in the rangelands and control bush encroachment. The shoots and seed pods of Vachellia nilotica were harvested and analyzed for fiber, protein, and mineral nutrients at different seed pods inclusion rates, with or without a feed additive. Six diets were selected for feeding 24 goats and quantifying seed recovery and germination after ingestion. Results indicated that including seed pods and feed additives to Vachellia nilotica shoots significantly improved the quality of the fodder. Chipping the seed pods prior to including them in the diet resulted in 13% intact seed recovery, and approximately 2% of these seeds were recovered after ingestion. These recovered seeds were mostly still viable but were still dormant as seed coats were not sufficiently damaged after ingestion. Therefore, viable seeds may still be dispersed in the rangeland, leading to further bush encroachment.

Connectivity and fragment size drive plant dispersal and persistence traits in forest steppe fragments

IntroductionLand use changes have seriously fragmented grasslands leading to extensive biodiversity loss worldwide. Habitat fragmentation affects grasslands at both local and landscape scales, adversely affecting the probability of species colonisation and extinction. In our study, we addressed the effects of fragment size and landscape-scale habitat connectivity on the vegetation composition in two grassland types, i.e., loess steppe fragments (situated on kurgans) and sand steppe fragments of the Pannonian forest steppe region.MethodsWe collected frequency data on vascular plant species in 12 1 m × 1 m quadrats in altogether 60 fragments along a connectivity gradient in sand steppes and loess steppe fragments. We analysed whether habitat specialists, generalists and exotic species were affected by the level of fragmentation based on species richness and traits related to local persistence (life span, clonality and soil seed bank type) and dispersal (dispersal strategy and seed mass) in the two grassland types using linear mixed-effects models.ResultsBased on our results, both fragment size and landscape-scale connectivity were important in shaping the trait composition of the vegetation. We observed more fragmentation effects in generalist than in specialist species. We found that isolation resulted in fewer specialist species with autochorous dispersal strategy in loess steppe fragments, but, at the same time, also fewer exotics. Isolated loess steppe fragments harboured fewer generalist species with persistent seed bank. Large loess steppe fragments supported more wind-dispersed species than smaller ones. In isolated sand steppe fragments, generalists were more frequent with endozoochorous dispersal strategy and without clonal propagation. Life span, clonal propagation and seed mass did not depend on the level of fragmentation in the two grassland types.DiscussionOur results imply that both sand and loess steppe fragments can rely to some extent on the persistence of clonal perennial specialist and generalist species in small and isolated patches to mitigate fragmentation effects. In conclusion, these processes should be supported by the preservation of large fragments, increase of habitat connectivity combined with targeted management of exotic species.

Acid scarification as a potent treatment for an in vitro germination of mature endozoochorous Vanilla planifolia seeds

BackgroundVanilla planifolia is the most widely cultivated species of vanilla with high economic importance. However, seed germination under artificial conditions is difficult and yields low germination percentages. The seeds are adapted to endozoochorous dispersal, and we therefore tried to simulate the conditions in the digestive tract by acid scarification of seeds.ResultsImmature seeds lacking dormancy, used as a control, showed the highest germination percentage. Among the treatments tested for mature seeds, the hydrochloric acid treatments were significantly the best in breaking dormancy and inducing germination, irrespective of the acid concentration and the presence of pepsin. Conventional treatment with a hypochlorite solution induced much lower germination percentage. Sulphuric acid at concentration 50% was too strong and caused damage to the seeds. Important factor is also high cultivation temperature 30 °C as there was nearly no germination at 25 °C.ConclusionsOur protocol significantly improves the efficiency of generative propagation of vanilla and allows for significantly higher germination percentages than previously described. The strongly positive effect of hydrochloric acid may be related to the adaptation of seeds to endozoochorous dispersal.

Bearing Fruit: Miocene Apes and Rosaceous Fruit Evolution

Extinct megafaunal mammals in the Americas are often linked to seed-dispersal mutualisms with large-fruiting tree species, but large-fruiting species in Europe and Asia have received far less attention. Several species of arboreal Maloideae (apples and pears) and Prunoideae (plums and peaches) evolved large fruits starting around nine million years ago, primarily in Eurasia. As evolutionary adaptations for seed dispersal by animals, the size, high sugar content, and bright colorful visual displays of ripeness suggest that mutualism with megafaunal mammals facilitated the evolutionary change. There has been little discussion as to which animals were likely candidate(s) on the late Miocene landscape of Eurasia. We argue that several possible dispersers could have consumed the large fruits, with endozoochoric dispersal usually relying on guilds of species. During the Pleistocene and Holocene, the dispersal guild likely included ursids, equids, and elephantids. During the late Miocene, large primates were likely also among the members of this guild, and the potential of a long-held mutualism between the ape and apple clades merits further discussion. If primates were a driving factor in the evolution of this large-fruit seed-dispersal system, it would represent an example of seed-dispersal-based mutualism with hominids millions of years prior to crop domestication or the development of cultural practices, such as farming.

Vitality of mycobionts and photobionts after passing through the digestive tract of Constrictotermes cyphergaster (Isoptera) workers.

Termites are among the insects that consume lichens and may be potential dispersers of these symbionts. This study evaluated the vitality of photobionts and mycobionts after passing through the digestive tract of Constrictotermes cyphergaster. The percentage of live and dead algae was verified throughout the alimentary canal of 450 workers, originating from five sampled colonies in the Caatinga Dry Forest, NE, Brazil. A progressive growth in algae mortality was observed in the crop, paunch and rectum, however more than 40% of the algae found in faeces presented signs of vitality. Photobiont morphology was different between cells extracted from thallus in natura and algae present in termite faeces. The photobiont cells presented more shrunken cytoplasms after passing through the alimentary canal of C. cyphergaster. There was also an increase between the cell wall space and the cytoplasm membrane of algae found in the termite faecal pellets. Only four broken spores were found in the intestine, which made the vitality analysis unfeasible for these cells. The record of photobiont vitality in termite faecal pellets is indicative of endozoochoric dispersal, suggesting that this relationship between insects and lichens extends beyond a trophic interaction.

Is endozoochoric seed dispersal by large herbivores an evolutionary adaptation? Revisiting the Janzen's ‘Foliage is the fruit’ hypothesis

Many plant species develop fruits to attract animals that will eat them and then disperse the seeds. However, there are many plant species, whose seeds are dispersed endozoochorically, but their fruits are not particularly attractive to animals. The “Foliage is the fruit” (FF) hypothesis proposes that entire biomass of the plant exists to encourage herbivores to eat it, in order to enhance seed intake and dispersal (Janzen, 1984).We tested the FF hypothesis by combining the results from the greenhouse seedling emergence method (GR) and DNA-metabarcoding of plant remnants in faeces of European moose (Alces alces L.). We processed 665 samples by the GR and 429 by the MB method, hypothesizing that if the safe passage of seeds through the gut of a large herbivore is the result of an evolutionary adaptation to endozoochoric dispersal, then the species composition of plants revealed by the two methods should largely overlap and the abundance of seedlings revealed by the GR method should be positively correlated in time with the read abundance of DNA of the same species. The large discrepancy between the lists of species detected by DNA metabarcoding and the GR method argues against the FF hypothesis. However, in the case of Urtica dioica, Lysimachia vulgaris and Lythrum salicaria, some clues of evolutionary adaptation to endozoochoric dispersal were revealed for: 1) their foliage is attractive to herbivores; 2) seeds are small, rounded in shape, yielded in large numbers and pass safely through the herbivore's gut; 3) the abundance of seeds (seedlings) was significantly and strongly influenced by the abundance of the plant biomass (DNA reads) in dung samples; 4) peaks in seed abundance and biomass consumption coincided in time. However, it should be considered that moose's diet is mostly composed of woody browse, which makes this animal not an optimal model for testing the Janzen's hypothesis and studies on typical grazers are needed in this respect.

Experimental assessment of endozoochorous dispersal of Prosopis flexuosa seeds by domestic ungulates

AbstractQuestionThe spatial and temporal dynamics of plant communities in various ecosystems are shaped by the movements of seeds expressed as different dispersal modes. In desert rangeland, many plants produce relatively large fruits that are limited in their long‐distance dispersal abilities and, therefore, depend on transport inside animals, a process termed endozoochory. Evaluating the effectiveness of this process from experimental data is crucial for assessing the potential of domestic ungulates as effective long‐distance seed dispersers and, consequently, as management and restoration tools in degraded rangelands.MethodsIn this study we jointly estimated recovery, gut retention time (RT) and germination probability of Prosopis flexuosa seeds (a tree species of Monte desert in Argentina) transported by goats, horses and cattle (n = 4) through a seed‐feeding experiment. Also, in horses and cattle, we used plastic particles to distinguish between seed loss due to mastication and due to degradation in the gut.ResultsResults showed higher seed recovery in horses (26%) than in cattle (3%) and goats (5%), and different values of RT and germination of seeds among species (in decreasing order, RT was: cattle > goats > horses; and germination was: goat > horses > cattle = control seeds).ConclusionsWe concluded that the quality of seed treatment by horses is better than by the other species, because of the high seed recovery and high germination compared to control seeds. To get a complete picture of this mutualistic interaction, future studies could inquire about the physical and chemical properties of faeces as substrate and the environmental conditions of sites where seeds are deposited.

Directed endozoochorous dispersal by scavengers facilitate sexual reproduction in otherwise clonal plants at cadaver sites.

The regeneration niche of many plant species involves spatially and temporally unpredictable disturbances, called recruitment windows of opportunity. However, even species with clear dispersal adaptations such as fleshy berries may not successfully reach such elusive regeneration microsites. Ericaceous, berry‐producing species in the northern hemisphere demonstrate this dispersal limitation. They are said to display a reproductive paradox owing to their lack of regeneration in apparently suitable microsites despite considerable investment in producing large quantities of berries.Cadavers generate vegetation‐denuded and nutrient‐rich disturbances termed cadaver decomposition islands (CDIs). Cadavers attract facultative scavengers with considerable capacity for endozoochorous seed dispersal. We hypothesize that CDIs facilitate recruitment in berry‐producing ericaceous species due to endozoochorous dispersal directed toward favorable microsites with low competition.We examined seedling establishment within a permanent, semi‐regular 10 × 10 m grid across an ungulate mass die‐off on the Hardangervidda plateau in southeastern Norway. Competing models regarding the relative importance of factors governing recruitment were evaluated, specifically cadaver location (elevated seed rain) and microsite conditions (competition).We found that CDIs did facilitate seedling establishment, as cadaver density was the best predictor of seedling distribution. Other important factors governing seedling establishment such as percentage cover of soil and vascular plants alone were inadequate to explain seedling establishment. Synthesis: This study provides a novel understanding of sexual reproduction in species with cryptic generative reproduction. The directed nature of endozoochorous dispersal combined with long‐distance dispersal abilities of medium to large vertebrate scavengers toward cadavers allows plants to exploit the advantageous but ephemeral resource provided by CDIs.

A predatory waterbird as a vector of plant seeds and aquatic invertebrates

AbstractOmnivorous waterbirds play an important role in aquatic ecosystems as dispersal vectors via direct ingestion, transportation, and egestion of plant and invertebrate propagules (i.e. endozoochory). Predatory birds also have the potential to disperse plants and invertebrates that were first carried internally or externally by their prey animals. However, the potential contribution of predatory waterbird species to propagule dispersal in aquatic ecosystems remains understudied.We chose the grey heronArdea cinerea(Ardeidae) to study the potential of predatory waterbirds to disperse propagules within and among aquatic ecosystems. We hypothesised that: (1) herons disperse a wide variety of plant and invertebrate propagules, from different habitats, with different morphologies (i.e. dispersal syndromes), and including both native and alien species; (2) propagules are ingested with prey species that are primary dispersal vectors (i.e., herons are secondary dispersers); (3) heron pellets show a similar abundance and richness of propagules across their widespread range. We collected 73 regurgitated heron pellets containing undigestible remains from 12 locations across the U.K. and The Netherlands, and examined the taxonomic diversity of plant seeds, invertebrates and prey remains.Pellets were dominated by mammal hairs (99% by volume), and bones confirmed the ingestion of small mammals (prevalence of 38%, e.g. water volesArvicola amphibius), fish (14%), and birds or amphibians (6%). A total of 266 intact plant seeds were recovered from 71% of the pellets, representing 50 taxa from 17 plant families, including the alienCotula coronopifolia. The cumulative number of plant species dispersed was lower at higher latitudes. Eight plant species recorded had not previously been recorded as dispersed via waterbirds, and only three species have anendozoochorous dispersal syndrome. Plant taxa were dominated by Caryophyllaceae, Cyperaceae, Juncaceae, and Poaceae, with 24 species from the littoral zone (Ellenberg moisture values of 7–12) and 21 terrestrial species (Ellenberg moisture values of 4–6). Intact invertebrate propagules were found in 30% of the pellets, dominated by Cladocera (Daphniidae) and Bryozoa (including the alienPlumatella casmiana).Our results demonstrate that grey herons disperse plant seeds and aquatic invertebrates widely in north‐western Europe. Herons regurgitate pellets that contain plant and invertebrate propagules from both aquatic or terrestrial habitats, for which secondary dispersal via ingestion along with prey is the likely underlying mechanism (i.e. propagules either attached to or in the digestive systems of the various prey). Our findings showcase the potential of predatory waterbirds as vectors of plants and invertebrates, and how they may facilitate connectivity between freshwater and terrestrial habitats.

Goats foster endozoochoric dispersal of exotic species in a seasonally dry tropical forest ecosystem

Goats at high densities are known to degrade vegetation in arid environments around the world. Their role as potential dispersers of seeds of native and exotic plant species, however, still remains uncertain. This study assesses whether goats, through endozoochorous seed dispersal, may potentially change the plant assemblage of seasonally dry tropical forests. We used seedling emergence as a method to analyze which plant species germinated from goat feces and thus may be dispersed by goats after passing through their intestinal tract. Seedling emergence data were analyzed with respect to the plot vegetation, water availability (permanent, temporary and no water courses), and altitude (as an indicator of anthropogenic pressure). We identified 18 species belonging to 14 families. Feces from the plots near permanent water with the largest anthropogenic pressure were characterized by the highest number of germinated plants. The most common plant species by far found in the experiment was the exotic Prosopis juliflora. This high abundance of P. juliflora seedlings shows that non-native grazers facilitate the spread of exotic plant species in threatened dry forest habitats. We therefore conclude that free-roaming goats may play an important ecological role in changing plant species assemblages of even remote areas.

Coexistence and bush encroachment in African savannas: The role of the regeneration niche

Abstract Globally there is increasing concern over the biodiversity and economic losses associated with bush encroachment. The dominant species responsible for bush encroachment in Africa belong to the mimosoid genera Senegalia and Vachellia, with previous research identifying Vachellia as the more aggressive invader. We asked whether these genera have evolved different traits to enable germination and establishment among competitively superior grasses. We hypothesised that these traits enable coexistence at local scales and underpin differences in invasiveness. We conducted a large greenhouse pot experiment to quantify functional trait differences between the two genera during seedling establishment both in the presence and absence of grasses. We also examined differences in seed morphology and tested whether co‐occurrence of the two genera at the plot scale is greater than expected by chance. Our results showed that Vachellia grew faster and taller than Senegalia in the absence of competition from grasses. In the presence of grasses, however, Senegalia increased root tissue density while Vachellia did not. The seed coats of Vachellia species were thicker than those of Senegalia, and their seeds were spherical while those of Senegalia were discoid. The two genera coexist at a local (plot) scale. We speculated that the thicker seed coat and spherical seed shape of Vachellia reflect its primarily endozoochorous dispersal mode, while the thinner seed coat and more discoid seeds of Senegalia reflect its use of wind dispersal. Since animal dispersal is directed, promoting the movement of seed into sites frequented by animals, and in which competition from grasses and fire has been removed, animal dispersal may contribute to the greater invasiveness of Vachellia. Once established in such sites, coexistence at the local scale is facilitated by differences in root tissue density with low‐density root tissue allowing for rapid resource acquisition and growth in Vachellia, and high‐density root tissue enabling slower but more persistent growth in Senegalia. Where previous research has focussed on environmental filtering, competition, predation or facilitation as explanations of plot‐scale phylogenetic overdispersion, our work suggests a potential role for regeneration niche in structuring local co‐occurrence. A free Plain Language Summary can be found within the Supporting Information of this article.

Endozoochorous dispersal by herbivores and omnivores is mediated by germination conditions

BackgroundVertebrate-mediated seed dispersal is probably the main long distance dispersal mode. Through endozoochory, large mammals act as mobile links between habitats within and among forest patches. Along with other factors, their feeding regimes do affect their contribution as dispersal vectors. We conducted a cross-species comparative experiment involving two herbivores, red deer and roe deer; and two opportunistic omnivores, wild boar and brown bear, all occurring in the forest and steppe-forest ecotone habitats of the south-eastern Caspian region. We compared their role as endozoochorous seed dispersal agents by monitoring seedling emergence in their dungs under greenhouse and natural conditions.ResultsIn total, 3078 seedlings, corresponding to 136 plant taxa sprouted from 445 paired dung sub-samples, under greenhouse and natural conditions. Only 336 seedlings, corresponding to 36 plant taxa, emerged under natural conditions, among which five taxa did not appear under greenhouse conditions. Graminoids and forbs composed 91% of the seedlings in the greenhouse whereas shrubs were more abundant under natural conditions, representing 55% of the emerged seedlings. Under greenhouse conditions, first red deer and then wild boar dispersed more species than the other two mammals, while under natural conditions brown bear was the most effective vector. We observed remarkably higher species richness and seedling abundance per dung sub-sample under buffered greenhouse conditions than we did under natural conditions.ConclusionsThe four sympatric mammals studied provided different seed dispersal services, both in terms of seedling abundance and species richness and may therefore be regarded as complementary. Our results highlight a positive bias when only considering germination under buffered greenhouse conditions. This must be taken into account when planning management options to benefit plant biodiversity based on the dispersal services concluded from greenhouse experiments.

Endozoochorous dispersal of forest seeds by carnivorous mammals in Sierra Fría, Aguascalientes, Mexico.

Some carnivorous mammals ingest fruit and disperse seeds of forest plant species capable of colonizing disturbed areas in ecosystems. The objective of the present study was to evaluate the dissemination of Arctostaphylos pungens and Juniperus deppeana seeds by the gray fox (Urocyon cinereoargenteus), coyote (Canis latrans), and other carnivores in the Protected Natural Area Sierra Fría, in Aguascalientes, Mexico. Scat collection was undertaken via transects using the direct search method, while the seasonal phenology of A. pungens and J. deppeana was evaluated by recording flower and fruit abundance on both the plant and the surrounding forest floor ground. Seed viability was assessed by optical densitometry via X‐ray and a germination test. It was found that the gray fox, coyote, ringtail (Bassariscus astutus), and bobcat (Lynx rufus) disseminated seeds of A. pungens (212 ± 48.9 seeds/scat) and J. deppeana (23.6 ± 4.9 seeds/scat), since a large proportion of the collected scat of these species contained seeds (28/30 = 93.33%, 12/43 = 27.9%, 6/12 = 50% and 7/25 = 28% respectively). The gray fox, coyote, ringtail, and bobcat presented an average of seed dispersion of both plant species of 185.4 ± 228.7, 4.0 ± 20.0, 12.1 ± 30.4, and 0.8 ± 1.5 per scat; the seed proportions in the gray fox, coyote, ringtail, and bobcat were 89.6/10.4%, 82.3/17.7%, 90.4/9.6%, and 38.1/61.9% for A. pungens and J. deppeana, respectively. The phenology indicated a finding related to the greater abundance of ripe fruit in autumn and winter (p < .01). This coincided with the greater abundance of seeds found in scats during these seasons. Endozoochory and diploendozoochory enhanced the viability and germination of the seeds (p > .05), except in those of A. pungens dispersed by coyote. These results suggest that carnivores, particularly the gray fox, the coyote, and the bobcat, play an important role in forest seed dissemination, and thus forest regeneration, by making both a quantitative and qualitative contribution to the dispersal of the two pioneer species under study.

Grazing animals drove domestication of grain crops.

In addition to large-seeded cereals, humans around the world during the mid-Holocene started to cultivate small-seeded species of herbaceous annuals for grain, including quinoa, amaranth, buckwheat, the millets and several lost crops domesticated in North America. The wild ancestors of these crops have small seeds with indigestible defences and do not germinate readily. Today, these wild plants exist in small fragmentary stands that are not appealing targets for foragers. This combination of traits has led many to argue that they must have been a food of last resort. We propose a new explanation: the domestication of small-seeded annuals involved a switch from endozoochoric dispersal (through animal ingestion) to human dispersal. Humans encountered these plants in dense stands created by grazing megafauna, making them easy to harvest. As humans began to cultivate these plants they took on the functional role of seed dispersers, and traits associated with endozoochory were lost or reduced. The earliest traits of domestication-thinning or loss of indigestible seed protections, loss of dormancy and increased seed size-can all be explained by the loss of the ruminant dispersal process and concomitant human management of wild stands. We demonstrate, by looking at rangeland ecology and herd animal herbivory patterns, that the progenitors of all of these species evolved to be dispersed by megafaunal ruminants and that heavy herbivory leads to dense homogenous clusters of endozoochoric plants. Hence, easily harvested stands on nitrogen hot spots near water sources would have existed in regions where these plants were domesticated. Future experimental and ecological studies could enhance our understanding of the relationships between specific crops and their possible ruminant dispersers.

Phylogeny of the Australian Solanum dioicum group using seven nuclear genes, with consideration of Symon's fruit and seed dispersal hypotheses.

The dioecious and andromonoecious Solanum taxa (the “S. dioicum group”) of the Australian Monsoon Tropics have been the subject of phylogenetic and taxonomic study for decades, yet much of their basic biology is still unknown. This is especially true for plant-animal interactions, including the influence of fruit form and calyx morphology on seed dispersal. We combine field/greenhouse observations and specimen-based study with phylogenetic analysis of seven nuclear regions obtained via a microfluidic PCR-based enrichment strategy and high-throughput sequencing, and present the first species-tree hypothesis for the S. dioicum group. Our results suggest that epizoochorous trample burr seed dispersal (strongly linked to calyx accrescence) is far more common among Australian Solanum than previously thought and support the hypothesis that the combination of large fleshy fruits and endozoochorous dispersal represents a reversal in this study group. The general lack of direct evidence related to biotic dispersal (epizoochorous or endozoochorous) may be a function of declines and/or extinctions of vertebrate dispersers. Because of this, some taxa might now rely on secondary dispersal mechanisms (e.g. shakers, tumbleweeds, rafting) as a means to maintain current populations and establish new ones.

Effects of grazing season and stocking rate on seed bank in sheep dung on the semiarid Loess Plateau

Endozoochorous dispersal of seeds by livestock has long attracted the attention of grassland scientists, but little is known about seed dispersal via Tan sheep dung on the dry grasslands of the Loess Plateau. We investigated the composition of dung seed bank of Tan sheep under summer and winter rotational grazing regimes at different stocking rates (2.7, 5.3 and 8.7sheepha–1), and assessed the relationships between seed mass and shape, egested seedling density and species richness and diversity. We also assessed the effects of stocking rate and grazing season on seedling density and species richness and diversity of the dung seed bank. Seeds of 10 pasture species germinated from Tan sheep dung with only two being annual species (Eragrostis pilosa and Chenopodium glaucum). The mean seed mass (±s.e.) was 2.59±0.23mg, ranging from 0.10mg (Cleistogenes songorica) to 10.59mg (Thermopsis lanceolata), and the mean seed shape index (±s.e.) was 0.10±0.02, ranging from 0.03 (Lespedeza bicolor) to 0.19 (Stipa bungeana). Species richness and diversity and seedling density decreased with increasing seed mass and shape index, suggesting that small, round seeds are most suitable for endozoochorous dispersal. Stocking rate had no effect on the number of germinated seeds that collected from summer or winter grazing pastures. Species richness and diversity and seedling density were greater in winter grazing pastures than in summer grazing pastures. Jaccard coefficients of similarity between the Tan sheep dung bank and aboveground vegetation were &amp;lt;0.5 for all stocking rates, indicating their weak relationship, but were significantly higher for winter than summer grazing. Plant seeds on the Loess Plateau could disperse through Tan sheep grazing, endozoochory can increase the heterogeneity of rotationally grazed plant communities, and this dispersal mode is an adaptation of plants to the harsh environment of the semiarid areas.

Endozoochorous seed dispersal by free-ranging herbivores in an abandoned landscape

Seed dispersal is a crucial process for the dynamics and maintenance of plant populations. Free-ranging animals are effective dispersal vectors because they can move between similar habitats and transport seeds into favourable environments. Dung samples from two species of common free-ranging mammals—deer and wild boar—were used to study endozoochorous dispersal of seeds in a military training area in western Bohemia. The area was abandoned after WWII, and the military training area was established in 1953. The vegetation consists of shrublands and dry grasslands. Data on the local species pool of grassland herbs and forbs were collected to compare the characteristics of dispersed versus non-dispersed plants. Deer and wild boar dispersed 84 plant species; however, species composition of seedlings emerging from dung samples showed significant differences between dispersal vectors and notable change across the growing season. 80% of all seedlings extracted from the dung samples belonged to stinging nettle, Urtica dioica. From trait analyses, seeds of endozoochorous plants had a higher longevity index in the soil seed bank than non-endozoochorous plants and more often possessed a mucilaginous surface. Our results show that deer and boar are successful, though not substitutable dispersers.

Endozoochorous dispersal of seeds of weedy rice (Oryza sativa L.) and barnyardgrass (Echinochloa crus-galli L.) by cattle

ABSTRACT: The objective of this study was to evaluate endozoochory dispersal, recuperation, and germination of weedy rice (Oryza sativa L.) and barnyardgrass (Echinochloa crus-galli L.) seeds passed through the digestive system of cattle. The experiment was divided into two phases: first, the daily seed recuperation rate was determined after passing through the digestive system of six steers. Each animal was dosed individually with 1000 weedy rice seeds and 13,818 barnyardgrass seeds, and these seeds were subsequently collected from feces. In the second phase, seed germination and emergence rate after passing or not passing through the digestive system of cattle were determined in two types of substrates (fecal plaque and soil) in a 2×2 factorial design. Seed recuperation in feces showed sigmoid behavior with maximum recovery on the second day after dosage. The recuperation of the species in the feces was 50.9% and 23.4% for weedy rice and barnyardgrass, respectively, which shows that both have potential endozoochory dispersal. However, seed germination of these species reduced after they passed through the digestive system, and they presented inferior emergence in the fecal plaque compared to the soil. The quarantine period for animals that ingest weedy rice and barnyardgrass seeds should be at least 6 and 7 days, respectively.