Search

Frugivore-mediated seed dispersal drives ecological functioning across tropical forests. The biological mechanisms affecting seed dispersal outcomes, as well as the role of specific functional traits in plants and their dispersers, is still not well understood. To address this gap, we conducted germination experiments in eight species of captive and two species of wild lemurs, which disperse different plant species. We (1) quantified the effects of pulp removal, seed priming, and feces effects (nutrient/microbial fertilization) through gut passage as mechanisms, (2) determined the effect of frugivore species on germination, and (3) assessed how individual plant and animal traits affected two seed germination outcomes: success rates and time-to-germination. Accounting for phylogenetic non-independence of plants and estimating phylogenetic signal, we evaluated the effects of lemur gut passage and functional traits in a Bayesian framework. Seed priming during gut passage was the primary mechanism through which lemurs improved germination rates and decreased time-to-germination. Gut passage influenced the effect of seed length on germination probability but not time-to germination. Germination outcomes varied by disperser species and seed size. Furthermore, seeds passed by male lemurs were 40% more likely to germinate than those passed by female lemurs. Germination probability was more similar for closely related plant species compared to those that were more distantly related, while the plant phylogenetic effects on time-to-germination were weaker. Moreover, germination depended on experimental setting; for example, lemur gut passage decreased time-to-germination in captive, but not wild settings. Our results highlight the complexity of biological mechanisms determining seed dispersal outcomes; ecological and evolutionary factors were important drivers of germination. Considering a diversity of potential effects is critical for advancing a mechanistic understanding of species interactions and their outcomes.

Frugivory and seed dispersal are fundamental ecological interactions influencing plant population dynamics and distribution. Still, understanding how the ingestion of seeds by fruit-eating animals affects seedling emergence performance remains poorly documented. Seed dispersal through animal ingestion can either promote or hinder germination. In this study, we assessed how seed ingestion by Saguinus bicolor, a critically endangered primate from the Brazilian Amazon, affects germination rate and germinability. As primate seed ingestion often improves seed germination, we predicted that germination rate and germinability would be higher in seeds defecated by the tamarins if compared to hand-extracted seeds. Of the 23 species, five did not germinated in either the control or gut-passage treatments. Among the ones that germinated, nine had an average increase in germinability, two decreased in germinability, and seven had a neutral effect. The germination rate increased in four species, reduced in eight species and had a neutral effect in six of the species. Most of the seeds that passed through the tamarins' digestive tract successfully germinated, demonstrating that seed ingestion by pied tamarins can benefit the plant populations by dispersing viable seeds through the landscape. [ABSTRACT FROM AUTHOR]

ABSTRACT Frugivore‐mediated seed dispersal drives ecological functioning across tropical forests. The biological mechanisms affecting seed dispersal outcomes, as well as the role of specific functional traits in plants and their dispersers, is still not well understood. To address this gap, we conducted germination experiments in eight species of captive and two species of wild lemurs, which disperse different plant species. We (1) quantified the effects of pulp removal, seed priming, and feces effects (nutrient/microbial fertilization) through gut passage as mechanisms, (2) determined the effect of frugivore species on germination, and (3) assessed how individual plant and animal traits affected two seed germination outcomes: success rates and time‐to‐germination. Accounting for phylogenetic non‐independence of plants and estimating phylogenetic signal, we evaluated the effects of lemur gut passage and functional traits in a Bayesian framework. Seed priming during gut passage was the primary mechanism through which lemurs improved germination rates and decreased time‐to‐germination. Gut passage influenced the effect of seed length on germination probability but not time‐to germination. Germination outcomes varied by disperser species and seed size. Furthermore, seeds passed by male lemurs were 40% more likely to germinate than those passed by female lemurs. Germination probability was more similar for closely related plant species compared to those that were more distantly related, while the plant phylogenetic effects on time‐to‐germination were weaker. Moreover, germination depended on experimental setting; for example, lemur gut passage decreased time‐to‐germination in captive, but not wild settings. Our results highlight the complexity of biological mechanisms determining seed dispersal outcomes; ecological and evolutionary factors were important drivers of germination. Considering a diversity of potential effects is critical for advancing a mechanistic understanding of species interactions and their outcomes.

Buttonweed (Cotula coronopifolia) is native to South Africa but invasive in wetlands in Europe, North America, and Australasia, where it excludes native plants. Despite being dry-fruited, field studies suggest migratory waterbirds can disperse its seeds via gut passage (endozoochory), aiding its expansion. To explore the potential for endozoochory in different regions and habitats, we collected seeds from six populations in Spain, Sweden, and the UK. Germination was tested under different salinity levels (0, 5, 10, 15 g/L) and simulated gut passage treatments: scarification, acidification, or both. No germination occurred at 15 g/L. Higher salinity reduced and delayed germination, but full gut passage treatment (i.e., both scarification and acidification) increased germinability and accelerated germination. Scarification or acid treatment alone resulted in intermediate germination patterns. There were significant salinity × population and gut passage × population interactions on germinability. The acceleration effect of gut passage on germination was stronger at 5–10 g/L than at 0 g/L. This study highlights how migratory birds can facilitate the spread of alien plants introduced by humans. Endozoochory by waterbirds is an understudied mechanism for the long-distance dispersal of dry-fruited alien plants. Further research on C. coronopifolia, including population genetics, is necessary to understand dispersal mechanisms and facilitate management strategies. [ABSTRACT FROM AUTHOR]

ABSTRACT Invasive species affect ecosystems all over the world. Their impacts intensify when there are beneficial effects among different invasive species, an invasional meltdown. The Argentine black and white tegu lizard, Salvator merianae (Squamata: Teiidae), and the plant Eugenia uniflora (Myrtaceae) are native to mainland South America but behave as invasive species in other parts of the world. We tested the effectiveness of S. merianae as a seed disperser of E. uniflora. Tegu feces containing seeds of E. uniflora were collected to compare the seed germination of gut-passed seeds, manually de-pulped seeds, and seeds of whole fruits. Survival analysis indicated that Tegu lizards behave as seed dispersers of E. uniflora, and there was a tendency for gut-passed seeds to germinate faster than non-gut-passed seeds. Tegu lizards may carry seeds in their guts for considerable distances, facilitating the spread of E. uniflora where both species co-occur as native and invasive (e.g., southern USA). The results indicate a mutualistic interaction between the Tegu lizard and E. uniflora in their native range, which should be considered by initiatives to monitor and control the invasion of the lizard and the plant.

Seed dispersal influences the survival and distribution of plant species and is an important mechanism for maintaining floristic diversity. Bushpigs (Potamochoerus larvatus) are large mammals of indigenous forests and well-wooded areas of eastern and southern Africa and may play an important role as seed dispersers. However, the diversity of fruits consumed and the effect of digestion on seeds remains poorly understood. This study was conducted from October 2018 to January 2019 and gives first insights into seed dispersal by bushpigs in the Soutpansberg Mountain range, South Africa. Here, we collected bushpig faeces and assessed the number of seeds and seed species found. Furthermore, germination experiments with digested and nondigested seeds and fruits were conducted. Our results show that bushpigs are omnivorous, consuming fruits and seeds of 126 different plant species. The proportion of seeds per plant species found in faeces was unhomogeneously distributed with a few hyperabundant species, in particular Searsia chirindensis (55%). The germination experiments showed that gut passage did, overall, not influence germination or seedling growth rates. However, seeds remaining within fruits showed reduced growth, pointing to a high importance of fruit consumption for seed fate. Our results suggest that bushpigs are major seed dispersers of a large variety of fruiting plant species in wooded areas of Africa. [ABSTRACT FROM AUTHOR]

Buttonweed (Cotula coronopifolia) is native to South Africa but invasive in wetlands in Europe, North America, and Australasia, where it excludes native plants. Despite being dry-fruited, field studies suggest migratory waterbirds can disperse its seeds via gut passage (endozoochory), aiding its expansion. To explore the potential for endozoochory in different regions and habitats, we collected seeds from six populations in Spain, Sweden, and the UK. Germination was tested under different salinity levels (0, 5, 10, 15 g/L) and simulated gut passage treatments: scarification, acidification, or both. No germination occurred at 15 g/L. Higher salinity reduced and delayed germination, but full gut passage treatment (i.e., both scarification and acidification) increased germinability and accelerated germination. Scarification or acid treatment alone resulted in intermediate germination patterns. There were significant salinity × population and gut passage × population interactions on germinability. The acceleration effect of gut passage on germination was stronger at 5–10 g/L than at 0 g/L. This study highlights how migratory birds can facilitate the spread of alien plants introduced by humans. Endozoochory by waterbirds is an understudied mechanism for the long-distance dispersal of dry-fruited alien plants. Further research on C. coronopifolia, including population genetics, is necessary to understand dispersal mechanisms and facilitate management strategies.

Migratory 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 for Daphnia magna to 36 hr for Artemia salina and Thamnocephalus 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 (Q99 distance).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, Q95 and Q99), 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). [ABSTRACT FROM AUTHOR]

Exploitation competition occurs when one group of organisms reduces the availability of a resource for another group of organisms. For instance, plants produce a certain number of fruits for seed dispersal by fruit‐eating animals (hereafter frugivores), and fruit consumption by one group of frugivores can reduce the number of fruits available for other frugivores. However, it is uncertain whether exploitation competition is common among frugivores, particularly in novel ecosystems, where food resources are generally thought to be abundant and invasive species are dietary generalists. In a novel ecosystem in Hawai'i, we used gut passage experiments with captive birds to identify roles of introduced frugivores and found they were either distinctly seed dispersers or predators. We then experimentally tested how frugivory by seed predators influenced frugivory by seed dispersers. Specifically, we used exclosures around fruiting plants that blocked seed predator access, while permitting seed disperser access, and we had two control treatments that allowed for access by all frugivores (n = 139 plants). When seed predators were excluded from plants, there was more frugivory by dispersers compared to controls, and results varied by year and plant species. Overall, we show that introduced frugivores occupied distinct ecological roles (seed predator or seed disperser), exploitation competition occurred between these introduced frugivore groups, and seed predators had both direct (via seed destruction) and indirect (via reduction in frugivory by dispersers) effects on seed dispersal. Thus, in this novel ecosystem, multiple frugivory is subtractive, and competition for fruit between introduced seed predators and seed dispersers scales up to affect invasions and the conservation of native flora. [ABSTRACT FROM AUTHOR]

Waterbirds disperse plant species via ingestion and egestion of seeds (endozoochory). However, our understanding about the regulating effects of seed traits, underlying mechanisms and possible (co)evolutionary processes is limited by our traditional reliance on data from feeding experiments with living waterbirds. Here, we overcome these limitations by developing and applying a new bioassay that realistically simulates digestive processes for Anseriformes waterbirds. We test three hypotheses: 1) seed survival and germination are most affected by mechanical digestion in the waterbird gizzard; 2) seed size, hardness, imbibition and shape regulate seed survival; and 3) plants growing in aquatic habitats benefit most from endozoochory by waterbirds. Experiments with 28 200 seeds of 48 plant species demonstrated species‐specific seed survival that was entirely determined by digestion in the avian gizzard. Intestinal digestion did not affect seed survival but affected seed establishment (germinability and germination time) for 21% of the species. Large, hard seeds survived the simulations the best, in contrast to generally higher seed survival for smaller seeds during in vivo experiments. This mechanistically explains that small seeds escape digestive processes rather than being inherently more resistant (the 'escape mechanism'), while large seeds are retained until fully digested or regurgitated (the 'resistance and regurgitation mechanism'). Plants growing in wetter habitats had similar seed survival, but digestive processes stimulated their germinability and accelerated their germination more than for terrestrial plants. This indicates a relative advantage of endozoochory for plant species growing in wet habitats, possibly reflecting a co‐evolutionary response related to dormancy breaking by gut passage. Simulating seed gut passage using a bioassay allowed establishing mechanisms and identifying relevant seed traits involved in seed dispersal by waterbirds. This information enhances our understanding of how animal species shape plant species distributions, which is extremely relevant now that current anthropogenic pressures already severely impact plant dispersal capacities. [ABSTRACT FROM AUTHOR]

Earthworms are keystone animals stimulating litter decomposition and nutrient cycling. However, earthworms comprise diverse species which live in different soil layers and consume different types of food. Microorganisms in the gut of earthworms are likely to contribute significantly to their ability to digest organic matter, but this may vary among earthworm species. Here, we analyse the effect of food (litter) quality on gut microbiota and their changes during the gut passage (from foregut to hindgut) of earthworms of different ecological groups. The endogeic (soil living) species Aporrectodea caliginosa and the anecic (litter feeding) species Lumbricus terrestris were fed with high- (rape leaves) and low-quality litter (wheat straw) in a microcosm experiment for 18 weeks. Irrespective of earthworm species, alpha diversity of bacterial and fungal communities changed little during the gut passage, with the composition and diversity of microbial communities in the gut generally resembling those in soil more than in litter. In addition, the low-quality litter supported higher alpha diversity and more complex communities than high-quality litter. Further, gut microbial communities of the anecic L. terrestris changed less during gut passage than those of the endogeic A. caliginosa , especially when fed low-quality litter. Our findings indicate that earthworm gut microbial communities are predominantly shaped by the soil they ingest, but are modulated by the quality of litter they feed on and earthworm ecological group. Overall, the results suggest that earthworms primarily influence soil microbiota by mixing and spreading microorganisms from different microhabitats through bioturbation rather than by digesting microorganisms., Competing Interests: The authors declare no conflicting interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.)

Large herbivores can disperse seeds over long distances through endozoochory. The Korean water deer (Hydropotes inermis argyropus), an internationally vulnerable species but locally considered a vermin, is a potential endozoochorous seed dispersal vector. In this study, feeding experiments were conducted to test the efficiency of seed dispersal through gut ingestion by the Korean water deer, its temporal pattern and the effect of gut passage on seed recovery and germination rate. Eight plant species, including species that formerly germinated from its faeces, were used to feed three Korean water deer. Once the deer had consumed all the provided seeds, their faeces were collected after 24, 48, 72 and 96 h. The collected faeces were air-dried, and the number of seeds retrieved from the faeces was counted every 24 h (0–24, 24–48, 48–72 and 72–96 h). Among the eight plant species, six species were retrieved with intact seeds. Panicum bisulcatum had the highest recovery rate of 33.7%, followed by Amaranthus mangostanus (24.5%) and Chenopodium album (14.4%). Most of the seeds were recovered within the 24–48 h time interval. Germination tests were conducted on the ingested and uningested seeds for the four species which had a sufficient recovery rate. The effects of gut passage on seed germination differed according to plant species. The germination rate substantially decreased after gut passage. The results suggest that the Korean water deer can disperse seeds, potentially over long distances albeit at a high cost of low seed recovery and germination rate. [ABSTRACT FROM AUTHOR]

Desiccation resistance is a key trait determining the distribution of aquatic insects, their potential for overland dispersal, and survival during drought periods in temporary waterbodies, as well as the spread of invasive species. Passive dispersal by waterbirds is considered to be a key process favouring the spread of invasive species and is more likely to occur for insects with eggs that are resistant to desiccation or gut passage.We investigated the hypothesis that the eggs of the alien boatman Trichocorixa verticalis verticalis are resistant to desiccation and digestion and thus able to disperse via waterbirds.We conducted experiments to test for egg resistance to desiccation in still air and under moving air conditions, to simulate bird flight. Oviposition on greater flamingo (Phoenicopterus roseus) legs and wetland plants was tested in the laboratory and in the field. Resistance of eggs to simulated gut passage was studied, as was the viability of eggs recovered from Eurasian coot (Fulica atra) droppings in the field.Only a fraction of eggs hatched after 8 hr of exposure to still air at 15°C (4% of exposed eggs), and after 2 hr exposure to air flow conditions at 20°C (8%). Oviposition on flamingo legs was confirmed in the laboratory but not in the field. However, oviposition rates were higher on plant stems than on flamingo legs. Digestion simulations showed very low resistance to chemical treatment and no resistance to scarification, and eggs recovered from coot droppings did not hatch.Our experiments demonstrated that T. v. verticalis cannot be considered to have eggs resistant to desiccation or gut passage. However, the dispersal of eggs on legs of flamingos or other waterbirds may occur as rare events. This epizoochory of eggs could potentially contribute to the expansion and gene flow of T. v. verticalis around the Mediterranean region. [ABSTRACT FROM AUTHOR]

Endozoochory is known as an important mechanism for the spread of weeds. We carried out experiments to assess the fate of seeds of several weed species (Convolvulus arvensis, Cuscuta campestris, Rumex crispus, Hordeum spontaneum and Sorghum halepense) after passing through the gut of sheep and goat. Eighteen animals of both sheep and goat received diet mixed with seeds of the weed species or control with only wheat bran (five weed species + control × three replications). Results showed that a higher proportion of seeds were missing after passage through the sheep gut than in goats. In goats, a greater proportion of seeds were dead after passage, but the number of seeds collected from dung was also greater. Weed species differed, with the highest seed recovery and viability in Cuscuta campestris. Based on time of seed passages through the animal gut estimated for the different weed species, we recommend that sheep should be kept in a corral for 96 hr to minimise seed transportation via their faeces. For goats, if R. crispus and C. arvensis seeds could be excluded from the diet, then maintaining them for 96 hr in an animal stall would ensure little seed transportation via dung, but we found R. crispus and C. arvensis seeds to be present and viable in goat dung even 120 hr after feeding. Very large numbers of viable seeds can be found in goat and sheep dung, so the use of rotted manure is highly recommended to avoid transportation of viable seeds via manure fertilisers. [ABSTRACT FROM AUTHOR]

Aims Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations. Seeds with dormancy may especially benefit after disperser gut passage. However, the ways in which gut passage affect the germination of plant species with physiological dormancy remain unclear. Here, we experimentally assessed the mutualistic interaction between the Austral parakeet (Enicognathus ferrugineus) as a disperser of calafate (Berberis microphylla), a thorny bush inhabiting the understory of the Austral temperate forests of South America with seeds that are characterized by deep physiological dormancy. Methods Germination success and viability of calafate seeds obtained from faeces and from intact fruits were tested under four treatments: (i) digested seeds, (ii) digested seeds with faecal extract, (iii) intact seeds from fruit and (iv) intact seeds from fruit with pulp. Important Findings About 65% of the Austral parakeet droppings contained calafate seeds. Viability of seeds did not differ between treatments. However, germination was significantly higher in digested seeds than in intact seeds from fruits, while no difference was found between faecal and pulp extracts. Neither faecal matter nor fruit pulp provided seeds with any ecological advantages derived from enhancing germinability, but did confer some disadvantage in germination time. Faecal matter is expected to be completely lacking around seeds after several months under snow before germinating in the following spring, given intense washing due to persistent rain and the spring thaw in the Patagonian Andes. The higher germinability along with faster germination of digested seeds supports the hypothesis of a legitimate mutualistic interaction between Austral parakeets and calafate. We hypothesized that the passage through the disperser digestive tract might break physiological dormancy as differences in germinability between ingested and non-ingested seeds. Our results highlight the relevant role of endozoochory in plant species with physiological dormancy living in highly seasonal environments. [ABSTRACT FROM AUTHOR]

Fruit ingestion by frugivores and the subsequent passage of seeds through their digestive tract can influence seed germination patterns. The removal of germination inhibitors contained in the fruit pulp (deinhibition effect), and/or the abrasion of the seed coat (scarification effect), can modify the probability and speed of seed germination. We followed seven groups of black-and-gold howler monkeys (Alouatta caraya) in northeastern Argentina between November 2012 and January 2013 to study the effect of seed passage through the howler monkeys' gut on seed germination. For three native and one exotic species, we compared the proportion of germination and germination times among seeds in three different treatments: gut-passed seeds (GP), manually extracted seeds from fruits (ME), and seeds in intact fruits (IF). Paired comparisons between treatments allowed us to assess the overall effect of seed passage (total effect without distinguishing individual effects, GP vs. IF), deinhibition effect (ME vs. IF), and scarification effect (GP vs. ME). Our results suggest that passage through the howler monkeys' gut enhances seed germination by an increase in the proportion of germinated seeds and/or by a reduction in germination times. We found that deinhibition enhanced germination in three out of the four studied species, while scarification enhanced germination in one and decreased germination in another species. Our work highlights that gut passage may affect seed germination by different mechanisms, and all of these mechanisms should be considered in germination studies. It also emphasizes the importance of A. caraya as a seed disperser in northeastern Argentina, showing the high quality of the treatment provided to seeds. [ABSTRACT FROM AUTHOR]

The use of goat browsing for invasive plant management is growing in the United States, but many questions remain about the efficacy of goat browsing for invasive plant control. One common concern of land managers and other stakeholders is whether goats can spread invasive plants through endozoochory (seed dispersal via ingestion and excretion in feces). We evaluated this possibility using common buckthorn (Rhamnus cathartica), an invasive shrub for which goats are often employed as a control method. Goats were fed buckthorn berries, and their feces were collected and examined at 24 hr, 48 hr, and 72 hr post-ingestion for intact seeds that survived gut passage. A low proportion of buckthorn seeds (2%) made it through the goat digestive system intact. Of these, only 11% remained viable, compared to 63% viability of control seeds. We conclude that consumption of buckthorn fruits by goats effectively destroys seeds, indicating low risk of dispersal via gut passage. To put these results in context, and provide more guidance for land managers, we additionally reviewed literature investigating seed recovery following ingestion by goats. Based on a synthetic analysis across 28 plant species, we found that seeds >4 mm long were unlikely to be recovered from feces intact, while smaller seeds posed higher dispersal risk. [ABSTRACT FROM AUTHOR]

Frugivorous birds are important in the dispersal of many fleshy-fruited plant species, including invasive plants. Consequently, we investigated three native frugivorous avian species' role in potential dispersal and germination success of the invasive American bramble (Rubus cuneifolius) in South Africa, particularly in terms of amount of fruit ingested, transit time, and their effects on seed germination. Three common species of frugivorous bird species were predicted to positively affect the spread of invasive R. cuneifolius. The bird species (speckled mousebirds Colius striatus, red-winged starlings Onychognathus morio and dark-capped bulbuls Pycnonotus tricolor) were fed R. cuneifolius fruit in captivity and amounts ingested were determined together with transit times. Seeds that were excreted and/or regurgitated by the three bird species, manually extracted seeds, and control whole fruit were then planted and their germination assessed daily. Although the three bird species varied in the amount of fruit consumed (~ 10–30 g), there was no significant difference in amount of R. cuneifolius fruit eaten per gram body mass among the species. Bird-ingested seeds emerged a mean 21–23 days after planting, while the seeds from the whole fruit took longer to emerge (mean 28 days). Germination of seeds ingested by the respective bird species was significantly higher (~ 60–75%) than seeds manually removed from fruits (~ 52%) or seeds in whole fruits (~ 7%). This suggests that removal of pulp and seed coat abrasion by the birds increased germination success. The three bird species all had R. cuneifolius seed transit times greater than 20 min, demonstrating their potential to disperse seeds a distance away from the parent plant. The results showed that the three bird species increased the germination success and suggests they are potentially important dispersers of the invasive R. cuneifolius. [ABSTRACT FROM AUTHOR]

Vermi-composting is considered to be a feasible method for reducing tetracycline resistance genes (TRGs) in the sludge. Nevertheless, the way different gut passages of earthworm might affect the fates of TRGs and whether this process is affected by tetracycline (TC) concentrations need to be further investigated. In this study, we examined the effects of TC concentrations on changes in TRGs and bacterial communities in gut passages of earthworm were determined by using quantitative PCR and Illumina high-throughput sequencing. TRGs and intI1 were mainly reduced in the hindgut under the TC concentrations ranging from 0 to 25 mg/kg, while they were enriched under higher TC stress exposure. Consequently, we suggest the TC limitation of 25 mg/kg in the domestic sludge (DS) for vermi-composting. Although the predominant genera were TC sensitive under TC stress, many bacterial hosts harboring multiple TRGs (especially those in the hindgut) should be paid further attention to. In the foregut, five genera with abundant tetracycline-resistant bacteria (TRB) were specialized taxa. Among these genera, Unclassified_Solirubrobacterales and Pirellulaceae were probably related to the digestion processes. Other unclassified taxa related to the TRGs were probably derived from the DS. Five genera with abundant TRB were shared in the gut passages, and three specialized genera in the hindgut. These genera could spread TRGs and intI1 to the environment. These results suggest that vermi-composting is a feasible approach for TRG control in the DS containing TC concentration that does not exceed 25 mg/kg. Fates of TRGs and intI1 widely differ in the gut passages, showing inevitable connections with bacterial communities. [ABSTRACT FROM AUTHOR]

On-going fragmentation of tropical forest ecosystems and associated depletion of seed dispersers threatens the long-term survival of animal-dispersed plants. These threats do not only affect biodiversity and species abundance, but ultimately ecosystem functions and services. Thus, seed dispersers such as the straw-coloured fruit bat, E. helvum, which traverse long distances across fragmented landscapes, are particularly important for maintaining genetic connectivity and colonizing new sites for plant species. Using high-resolution GPS-tracking of movements, field observations and gut retention experiments, we quantify dispersal distances for small- and large-seeded fruits foraged by E. helvum during periods of colony population low (wet season) and high (dry season) in an urban and a rural landscape in the forest zone of Ghana. Gut passage time averaged 116 min (range 4–1143 min), comparable to other fruit bats. Movements were generally longer in the urban than in the rural landscape and also longer in the dry than in the wet season. As the majority of seeds are dispersed only to feeding roosts, median dispersal distances were similar for both large (42–67 m) and small (42–65 m) seeds. However, small seeds were potentially dispersed up to 75.4 km, four times further than the previous maximum distance estimated for a similar-sized frugivore. Maximum seed dispersal distances for small seeds were almost twice as long in the rural (49.7 km) compare to the urban (31.2 km) landscape. Within the urban landscape, estimated maximum dispersal distances for small seeds were three times longer during the dry season (75.4 km) compared to the wet season (22.8 km); in contrast, distances in the rural landscape were three times longer in the wet season (67 km) compared to the dry season (24.4). Dispersal distances for large seeds during the dry season (551 m) in the rural landscape were almost twice that in the wet season (319 m). We found no influence of food phenology on dispersal distances. The maximum likelihood for seed dispersal beyond feeding roosts (mean distance from food tree 263 m) was 4.7%. Small seeds were dispersed over even longer distances, >500 and >1000 m, with a likelihood of 3.0 % and 2.3 % respectively. Our data show that E. helvum retains ingested seeds for very long periods and may traverse large distances, probably making it an important long distance seed disperser in tropical Africa. We suggest E. helvumis important for ecosystem functioning and urge its conservation.

Current understanding of mutualistic networks is grounded largely in data on interaction frequency, yet mutualistic network dynamics are also shaped by interaction quality—the functional outcomes of individual interactions on reproduction and survival. The difficulty of obtaining data on functional outcomes has resulted in limited understanding of functional variation among a network's pairwise species interactions, of the study designs that are necessary to capture major sources of functional variation, and of predictors of functional variation that may allow generalization across networks.In this community‐scale study, we targeted a key functional outcome in plant–frugivore networks: the impact of frugivore gut passage on seed germination. We used captive frugivore feeding trials and germination experiments in an island ecosystem, attaining species‐level coverage across all extant native frugivores and the plants they consume to (a) assess sources of functional variation, (b) separate effects of pulp removal from those of scarification via gut passage, and (c) test trait‐based correlates of gut passage effect sizes.We found antagonistic seed predation effects of a frugivore previously assumed to be a seed disperser, highlighting the need to consider functional outcomes rather than interaction frequency alone. The other frugivores each exhibited similar impacts for individual plant species, with benefits primarily caused by pulp removal rather than scarification, supporting the use of animal functional groups in this context. In contrast, plant species varied widely in impacts of gut passage on germination. Species with smaller seeds and more frugivore partners had larger benefits of gut passage, showing promise for network metrics and functional traits to predict functional variation among plants.Synthesis. Combining network and demographic approaches, we assessed the degree and sources of variation in a key functional outcome of plant–frugivore interactions across an entire network. Using a detailed study design, our work shows how simpler study designs can capture primary sources of functional variation and that functional traits and network metrics may allow generalization across networks. Efficiently measuring and generalizing sources of functional variation within mutualistic networks will strengthen our ability to model network dynamics and predict mutualist responses to global change. A challenge for mutualistic network research is to incorporate information on the functional outcomes of interactions rather than focus on interaction frequency alone. For an entire network, we measured a key functional outcome of plant–frugivore interactions: the impact of gut passage on germination. Demonstrating potential for generalization, we show support for using animal functional groupings, for simpler study designs to capture key functional variation, and for functional traits and network metrics as predictor of functional variation. [ABSTRACT FROM AUTHOR]

Heretofore, no study has determined how germination of ingested seeds is affected by the kind (class) of dormancy nor by seed dormancy x seed size interaction. Thus, we aimed to determine the effects of seed size, kind of dormancy and their interaction on germination of defecated seeds using a meta-analysis. We collected data for 366 plant species in 97 plant families from 76 publications. In general, gut passage significantly increased germination percentage of defecated seeds by 5% compared with that of control seeds. Germination percentages of non-dormant, physiologically dormant, and morphologically/morphophysiologically dormant seeds (all water-permeable) significantly decreased after gut passage by 40, 18, and 14%, respectively, compared with control seeds (non-gut-passed). Changes in germination percentage of seeds with physical dormancy (water-impermeable) were positive, and gut passage increased germination by 69% compared with control seeds. Germination of small seeds decreased 8% after gut passage, whereas germination of both medium and large seeds increased by 18%. However, changes in germination percentage differed between categories of seed size in each class of dormancy. In physically dormant seeds, germination of all seed sizes improved after gut passage, and the magnitude of increase was higher for large than for medium and small seeds. Thus, gut passage increased germination of medium-size water-permeable seeds (physiologically dormant and morphologically/morphophysiologically dormant) more than it did for large and small seeds. However, gut-passage decreased or did not change the germination percentage of non-dormant seeds. Seed size and kind of dormancy should be included in studies on the effect of gut passage on germination. [ABSTRACT FROM AUTHOR]

Abstract: Species interactions, both mutualistic and antagonistic, are widely recognized as providing important ecosystem services. Fruit‐eating animals influence plant recruitment by increasing germination during gut passage and moving seeds away from conspecifics. However, relative to studies focused on the importance of frugivores for plant population maintenance, few studies target frugivores as ecosystem service providers, and frugivores are underappreciated as ecosystem service providers relative to other mutualists such as pollinators. Here, we use an accidental experiment to elucidate the role of seed dispersal by frugivores for maintaining a culturally and economically important plant, the donne’ sali chili (Capsicum frutescens) in the Mariana Islands. One of the islands (Guam) has lost nearly all of its native forest birds due to an invasive snake (Boiga irregularis), whereas nearby islands have relatively intact bird populations. We hypothesized that frugivore loss would influence chili recruitment and abundance, which could have economic and cultural impacts. By using video cameras, we confirmed that birds were the primary seed dispersers. We used captive bird feeding trials to obtain gut‐passed seeds to use in a seedling emergence experiment. The experiment showed that gut‐passed seeds emerged sooner and at a higher proportion than seeds from whole fruits. Consistent with our findings that birds benefit chilies, we observed lower chili abundance on Guam than on islands with birds. In a survey questionnaire of island residents, the majority of residents reported an association between the wild chili and local cultural values and traditions. In addition, we identified a thriving market for chili products, suggesting benefits of wild chilies to people in the Marianas both as consumers and producers. Our study therefore documents seed dispersal as both a cultural and a supporting ecosystem service. We provide a comprehensive case study on how seed‐dispersed plants decline in the absence of their disperser, and how to apply mixed‐methods in ecosystem service assessments. Furthermore, we suggest that scientists and resource managers may utilize fruit–frugivore mutualisms concerning socially valuable plants to gather support for frugivore and forest conservation efforts. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mycophagists can influence fungal diversity within their home ranges by ensuring the continued and effective dispersal of spores from one site to another. However, the passage of spores through the digestive tract of vertebrates can affect the activity and viability of the spores ingested. This phenomenon has been rarely documented in opportunistic mycophagists consuming epigeous fungi. Using laboratory experiments, we investigated the activity and viability of spores of two epigeous ectomycorrhizal fungal species (Laccaria trichodermophora and Suillus tomentosus) after passage through the digestive tract of two opportunistic mycophagous small rodents, the volcano mouse Peromyscus alstoni and the deer mouse P. maniculatus. We found that passage through the gut of either species of rodent had a significant effect on spore activity and viability for both fungal species. The proportion of active spores (0.37–0.40) of L. trichodermophora in the feces of both species of rodents was less than that recorded for the control (0.82). However, the proportion of active spores (0.64–0.73) of S. tomentosus in the feces of each species of rodent was higher than in the control (0.40). On the other hand, the viability of spores was lower (0.26–0.30 in L. trichodermophora and 0.60–0.69 in S. tomentosus) for both fungi when consumed by either rodent relative to the controls (0.90 in L. trichodermophora and 0.82 in S. tomentosus). These findings suggest that these rodent species may be effective dispersers of both epigeous fungi [Current Zoology 57 (3): 293–299, 2011].

The degree of seed scarification in the frugivore gut, partly dependent on gut retention time, is a key component in determining the extent to which gut passage alters germination performances. Another potential benefit of gut passage arises as a result of the removal of fruit pulp which otherwise may act as a germination inhibitor. Using experiments designed to disentangle the respective effects of pulp removal (germination deinhibition) and seed scarification, and gut retention time as an explanatory variable, we investigated the effect of gut passage on germination performances (percentage and latency) of five tropical tree species dispersed by the western lowland gorilla ( Gorilla g. gorilla ). The percentage of seeds germinating after gut passage increased for three species, respectively, through the effects of scarification only, deinhibition only, and scarification and deinhibition combined. A negative scarification effect was observed for one species, and no effect of gut passage for another. Passage through the gut led to a decrease in germination latency of three species, as a result of the depulping of seeds. However, seed scarification resulted in germination delays for another species. The gut retention time of the five species averaged 39–56 h and had no effect on intra-specific germination performances except for one species whose germination probability increased as gut retention time increased. As gut retention time often correlates with dispersal distance, the fact that gut retention time per se does not reduce seed viability of these tropical tree species may have positive implications for their population dynamics and maintenance of genetic diversity. If no detrimental effect of gut retention time on germination performance is a general trait among tropical species, the extirpation of large frugivores with long gut retention time, such as the western lowland gorilla, would likely have negative long-term implications for tropical forests. [ABSTRACT FROM AUTHOR]

The round goby (Neogobius melanostomus) is a Ponto-Caspian invader of North America that preys heavily on dreissenid mussels (Dreissena polymorpha and Dreissena rostriformis bugensis) in its native and invaded ranges. Efficient predation on mollusks by fish requires crushing of shells so that digestive enzymes can access soft tissue of the prey. The purpose of this experiment was to determine if dreissenids and other prey survive passage through the digestive system of round gobies. N. melanostomus were collected from Presque Isle Bay of Lake Erie and a nearby invaded pond (Erie Co., Pennsylvania) and placed individually into containers filled with aged tap water. After 24-48 h of isolation, feces were surveyed under a stereomicroscope for moving prey. Neutral red, which stains lysosomes of living cells, was also used to determine if intact bivalves were alive. No dreissenids survived passage through the gut of N. melanostomus, but variable numbers of other prey, including 16.6% of ostracods, were recovered alive. These results suggest that N. melanostomus is adapted to feeding on dreissenids, but round gobies may be less well-adapted to feeding on other hard-bodied prey. Passage of live prey through the gut also has implications on energy budgets of the round goby and its ability to function as a dispersive agent for other species. [ABSTRACT FROM AUTHOR]

The growth and photosynthetic activities of Cyanobacteria passed through the gut of silver carp ( Hypophthalmichthys molitrix), bighead carp ( Aristichthys nobilis), and tilapia ( Oreochromis niloticus) were compared with those of phytoplankton taken directly from Lake Taihu during a 13-day in situ dialysis culture. After the first 3-5 days of reduced activity after excretion by silver carp and bighead carp, the photosynthetic activity of Cyanobacteria recovered and rose significantly higher ( P < 0.01) than levels in the control population, whereas there was a notable reduction of photosynthetic activity after passage through tilapia gut. The phytoplankton biomass showed a 2- to 3-fold increase of growth, and extracellular polysaccharide production was also stimulated after passage through silver carp and bighead carp gut. Chlorophyta fluorescence was detected at much higher levels than that of Cyanobacteria and Bacillariophyta after passage through tilapia gut. Scenedesmus obliqnus and Chlamydomonas sp. contributed much to the growth of the Chlorophyta during the in situ cultivation. However, the total phytoplankton biomass showed a distinct reduction in the tilapia treatment during the culture. The study indicated that Nile tilapia feeding and defecation may help remove Cyanobacteria from the water column and favor a community shift to Chlorophyta. [ABSTRACT FROM AUTHOR]

Long-distance dispersal of aquatic invertebrates is in many cases facilitated by resistant life stages surviving the passage through the gut of water birds. While this is well known for taxa like crustaceans and bryozoans, it has only very rarely been documented for aquatic insects., The fully aquatic leaf beetle Macroplea mutica shows a remarkably wide distribution throughout the whole Palearctic region, despite showing very little potential for active dispersal. The aim of this study was to test the potential for endozoochorous dispersal in Macroplea mutica by feeding beetle eggs to mallards ( Anas platyrhynchos). It was hypothesised that eggs of these water beetles might survive internal transport within birds., Approximately 1% of ingested M. mutica eggs could be retrieved from faeces of mallards 2-8 h after ingestion. Larvae hatched from 20% of the retrieved eggs after gut passage., These results represent one of the first documented cases of insects surviving the gut passage through a water bird, and the first experimental evidence of the potential for bird-mediated endozoochorous dispersal of aquatic beetles. The possibility of internal transport could help to explain the remarkably wide distribution of an otherwise strikingly immobile beetle species. [ABSTRACT FROM AUTHOR]

Microarthropods are known as vectors for soil microorganisms, predominantly fungi. This laboratory study uses the widespread unicellular green algae Chlorella vulgaris as model to assess the role of Collembola in algal dispersal and to determine the effects of gut passage on propagation. Living algal cells were observed in 70 % of the faecal pellets of Folsomia candida, Heteromurus nitidus and Protaphorura fimata. Moreover, marker fatty acids for green algae, i.e. 16:2ω6,9 and 16:3ω3,6,9, were consistently detected in the pellets. Compared to the algal diet, the high content of methyl-branched total lipid fatty acid (TLFA) with hydroxyl substitution indicated microbial colonisation during gut passage. The TLFA profile of faeces revealed no species-specific differences but similar changes in microbial communities over the duration of feeding, indicating comparable indigenous bacteria and colonisation mechanisms during gut passage. In sum, faecal pellets of soil microarthropods such as Collembola can act as a vector for both dietary algae and specific gut-associated microorganisms, with the latter likely involved in resource degradation inside and outside the gut habitat. [ABSTRACT FROM AUTHOR]

Abstract: The dispersion and seedling establishment of pioneering plants can be favoured by the presence of frugivorous bats because the bats usually improve seed germination after ingestion. Although seed germinability is known to vary greatly after ingestion by different bats, the relative contribution of each bat species to seed germination within plant communities is poorly understood. In this study, we first determined the fauna of frugivorous bats in a semideciduous seasonal forest remnant in southern Brazil and subsequently identified the plant species of the seeds passed through their guts. Second, the germination performance (i.e., germination percentage and speed) of the seeds of three pioneering plants (Piper aduncum, Piper hispidinervum and Solanum granuloso-leprosum) ingested by the most abundant bats was compared with that of the non-ingested seeds (seeds collected from fruits). Additionally, the effects on seed germination of different bat species were compared. During one year, five species of frugivorous bats were caught, and the seeds of eleven identifiable plant species (not counting those of undetermined species) were found in their faeces. We found that the germination performance of the seeds of Piper species was significantly enhanced after ingestion by bats, whereas S. granuloso-leprosum seeds had neutral or reduced germinability when seeds in faeces were compared with pulp-removed seeds. Our results revealed that the bat species that were captured exerted different effects upon seed germination; such a disparity is expected to result in different rates of early establishment of these pioneer plants in tropical forests, most likely affecting forest composition and structure, particularly during the initial stages of succession. [Copyright &y& Elsevier]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The introduction and spread of invasive species is of great concern to natural resource managers in the United States. To effectively control the spread of these species, managers must be aware of the multitude of dispersal methods used by the organisms. We investigated the potential for survival through the gut of a migrating fish (blue catfish, Ictalurus furcatus) as a dispersal mechanism for two invasive bivalves: zebra mussel ( Driessena polymorpha) and Asian clam ( Corbicula fluminea). Blue catfish (N = 62) were sampled over several months from Sooner Lake, Oklahoma, transported to a laboratory and held in individual tanks for 48 h. All fecal material was collected and inspected for live mussels. Survival was significantly related to water temperature in the lake at the time of collection, with no mussels surviving above 21.1 C°, whereas 12 % of zebra mussels (N = 939) and 39 % of Asian clams (N = 408) consumed in cooler water survived gut passage. This research demonstrates the potential for blue catfish to serve as a dispersal vector for invasive bivalves at low water temperatures. [ABSTRACT FROM AUTHOR]

Aims The use of exotic species as taxon substitutes to restore lost ecological interactions is currently hotly debated. Aldabrachelys gigantea giant tortoises have recently been introduced to three islands in the Mascarene archipelago (Ile aux Aigrettes, Round Island and Rodrigues) to resurrect herbivory and seed dispersal functions once performed by extinct giant tortoises. However, potential unintended impacts by frugivore substitutes on native ecosystems, e.g. whether they will facilitate the germination of exotic plant species, are largely unknown. We investigated whether A. gigantea introduced to Rodrigues in 2006 could enhance the germination percentage of four widespread fleshy-fruited exotic species on the island. Using germination trials to forecast unintended impacts that could arise from the introduction of a frugivorous taxon substitute enables conservation managers to limit potential adverse negative interactions before they occur. Methods In germination trials that ran over 4 months, we investigated the effects of ingestion (gut passage and deposition in faeces) by sub-adult and adult A. gigantea on the germination percentage of four exotic fleshy-fruited plant species introduced to Rodrigues. We fed fruits of these plant species to sub-adult and adult A. gigantea to test how variation in age and size of the frugivore would affect seed germination. Feeding of distinctly coloured plastic pellets together with the fruits allowed us to test for individual tortoise effects on seed germination. Important Findings Ingestion by A. gigantea increased the percentage of seeds germinating of Mimusops coriacea and Lantana camara, but not percentage of germination of Veitchia merrillii or Wikstroemia indica. Seeds were more likely to germinate following ingestion by sub-adult rather than adult tortoises, which may be a consequence of the shorter gut passage time observed for sub-adults. Our results demonstrate that introduced frugivorous taxon substitutes could facilitate germination of exotic and invasive plants and highlight the need for conservation managers to weigh the risk of taxon substitutes potentially facilitating the germination and recruitment of exotic fleshy-fruited plants against the benefit of restoring lost seed dispersal functions of threatened indigenous plants. Our findings also highlight the importance of considering age and size variation in frugivores, in particular in long-lived taxa such as giant tortoises, when studying ingestion effects on the germination performance of plants. [ABSTRACT FROM AUTHOR]

The spread of many invasive plants is facilitated through seed dispersal by frugivorous animals. The effectiveness of various frugivores as dispersers of the seeds of Melia azedarach, a highly invasive alien tree species, was evaluated in South Africa in savanna and bushveld vegetation. During 264 h of observation, seven bird species and one bat species were recorded foraging on fruiting trees of M. azedarach. The most common visitors were the dark-capped bulbul (Pycnonotus barbatus) followed by Wahlberg's epauletted fruit bat (Epomophorus wahlbergi), but both species dropped nearly as many seeds as they dispersed. Knysna turaco (Tauraco corythaix) dispersed the highest number of fruits per minute, but occurred in low abundance in our study sites. Seed germination differed significantly between de-pulped fruits and untreated fruits after 2 mo, but was similar after 4 mo. Germination success did not differ between animal-handled and hand-depulped fruits. In contrast to the high germination success in the greenhouse, seedlings showed very low recruitment in the field. Thus, M. azedarach seems likely to benefit from frugivores (particularly dark-capped bulbul and Wahlberg's epauletted fruit bat) dispersing seeds to suitable microsites. [ABSTRACT FROM PUBLISHER]

Mycophagists can influence fungal diversity within their home ranges by ensuring the continued and effective dispersal of spores from one site to another. However, the passage of spores through the digestive tract of vertebrates can affect the activity and viability of the spores ingested. This phenomenon has been rarely documented in opportunistic mycophagists consuming epigeous fungi. Using laboratory experiments, we investigated the activity and viability of spores of two epigeous ectomycorrhizal fungal species (Laccaria trichodermophora and Suillus tomentosus) after passage through the digestive tract of two opportunistic mycophagous small rodents, the volcano mouse Peromyscus alstoni and the deer mouse P. maniculatus. We found that passage through the gut of either species of rodent had a significant effect on spore activity and viability for both fungal species. The proportion of active spores (0.37–0.40) of L. trichodermophora in the feces of both species of rodents was less than that recorded for the control (0.82). However, the proportion of active spores (0.64–0.73) of S. tomentosus in the feces of each species of rodent was higher than in the control (0.40). On the other hand, the viability of spores was lower (0.26–0.30 in L. trichodermophora and 0.60–0.69 in S. tomentosus) for both fungi when consumed by either rodent relative to the controls (0.90 in L. trichodermophora and 0.82 in S. tomentosus). These findings suggest that these rodent species may be effective dispersers of both epigeous fungi [Current Zoology 57 (3): 293–299, 2011]. [ABSTRACT FROM AUTHOR]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fruit-eating animals can influence the germination success of seeds through transportation and handling. We experimentally tested the contribution of ingestion by the common fruit-eating bat, Artibeus jamaicensis (Phyllostomidae, Chiroptera), to the percentage and rate of seed germination of figs ( Ficus, Moraceae), which are considered keystone species for many frugivores. We collected fruits from three species of native free-standing figs (subgenus Pharmacosycea: F. insipida, F. maxima and F. yoponensis) and three species of native strangler figs (subgenus Urostigma: F. nymphiifolia, F. obtusifolia and F. popenoei) on Barro Colorado Island, Panama. The germination success of seeds removed from fruit pulp either manually or by ingestion was very high (>92%), while seeds that were not removed from fruit pulp were destroyed by fast-growing fungi within a few days. The dynamics of seed germination were not influenced by ingestion, but differed between the two subgenera of figs. In free-standing figs, germination started significantly earlier (5.3 ± 0.7 days) than in strangler figs (8.6 ± 1.4 days). Furthermore, strangler seeds were covered with a sticky coating and their seedlings developed cotyledons faster than fine roots, in contrast to free-standing figs that showed the opposite pattern. Our results demonstrate that the germination of fig seeds is positively influenced by passage through the gut of A. jamaicensis. Furthermore, free-standing and strangler figs revealed differences in germination parameters that might be adaptive with respect to the suitability of microsites such as tree fall gaps or host trees for establishment. [ABSTRACT FROM AUTHOR]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article discusses a study which investigated the use of both isotopically labeled and hygromycin-resistant fungus in tracing Aspergillus sydowii in corals. The study traced the pathogen through the guts of the snail Cyphoma gibbosum from ingestion to feces. It used a choice-feeding assay to assess the ecological likelihood of snails feeding on diseased corals. It showed that snails fed antifungal-resistant Aspergillus sydowii excrete viable spores and hyphae in their feces. The study affirmed the effectiveness of isotopic labeling and antifungal-resistant fungi in tracing the movement of pathogen propagules.

Copyright of Tropical Conservation Science is the property of Sage Publications Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The occurrence of new phytoplankton species in a coastal area may be explained by the import of shellfish containing whole live algal cells in their digestive tracts. Indeed, shellfish containing toxic algal cells can induce both primary contaminations in safe areas (initially free from toxic microalgae), and secondary contaminations of other shellfish growing in the same area via the faeces of the imported animals. To mitigate this problem, shellfish need to be placed in a separate holding tank and their intestinal content purged. For a deeper understanding of the risks associated with transferring contaminated shellfish, oysters (Crassostrea gigas) and mussels (Mytilus edulis) were purposely fed either Alexandrium minutum or A. catenella (Dinophyceae) or Pseudo-nitzschia calliantha (Bacillariophyceae) toxic algae for 2 h. They were then transferred into individual tanks where they were continuously fed with a non-toxic alga, Tetraselmis suecica. Biodeposit production, faeces composition, and filtration rates were monitored for the shellfish over a 6-h period. The effect of temperature differences and different initial toxic algae concentrations were compared. This study revealed a relationship between temperature and cell lysis in the oyster digestive tract. It also indicated that toxic algae concentration did not seem to influence gut passage time in oysters, while a significant effect was observed in mussels, and confirmed the existence of a difference between oyster and mussel feeding patterns. [ABSTRACT FROM AUTHOR]

Freshwater mollusks figure prominently in the diets of humpback whitefish (Coregonus pidschian) and broad whitefish (C. nasus), two benthic-feeding coregonid species. A recent examination of pea clams (Sphaeriidae), valve snails (Valvatidae), and pond snails (Lymnaeidae) from the lower digestive tracts of these fish found that many of the mollusks were alive. Survival completely through gut passage would indicate a dispersal mechanism for freshwater mollusks that has not been previously recognized. A field investigation was conducted with wild-caught humpback and broad whitefish to test the hypothesis that clams and snails are capable of surviving complete gut passage. Wild fish were captured alive and held in collection totes to obtain feces samples. Pea clams and valve snails were abundant in fish feces, and pond snails were present but not abundant. An average of 483 pea clams and 833 valve snails per fish were observed to have survived complete gut passage, while only a single surviving pond snail was found. These findings suggest that fish may play an important role in the dispersal of freshwater mollusks within freshwater systems. [ABSTRACT FROM AUTHOR]

1. The potential for seed dispersal by fish (ichthyochory) will vary among aquatic plants because of differences in seed size and morphology. 2. To examine how seed morphology influences the probability of dispersal by the common carp ( Cyprinus carpio), we studied seed ingestion, retention time and subsequent egestion and germination of seeds of Sparganium emersum and Sagittaria sagittifolia, two aquatic plant species with similar sized but morphologically different seeds. 3. We compared dispersal probabilities between the two plant species, in which the probability of dispersal is assumed to be a function of the probabilities of seed ingestion, egestion and germination, and the dispersal distance is assumed to be a function of seed egestion rate over time. 4. We found that, although the soft seeds of S. sagittifolia had an approximately 1.5 times higher probability of being ingested by the carp than the hard seeds of S. emersum (83.15% ± 1.8% versus 56.16% ± 2.7%, respectively), the latter had an almost twofold higher probability of surviving the passage through the digestive tract (38.58% ± 2.7% versus 20.97% ± 1.5%, respectively). Patterns of seed egestion over time did not differ between the two plant species, despite the difference in seed morphology. Gut passage had a different effect on seed germination between plant species. Compared with non-ingested controls, seeds of S. emersum showed a 12.6% increase in germination and a 2.1 day acceleration in germination rate, whereas seeds of S. sagittifolia displayed a 47.3% decrease and 5.1 day delay, respectively. 5. Our results suggest that seed morphology affects the dispersal probability and postdispersal establishment, but not the dispersal distance, of aquatic plants that are dispersed by fish. [ABSTRACT FROM AUTHOR]

Soil macrofauna play important roles in the mobilization of soil nutrients. The influence of gut passage on soil phosphorus availability was investigated using the larvae of the scarabaeid beetle Pachnoda ephippiata. Gut passage significantly increased the levels of available P in the feces over that of the soil consumed. 31P-NMR recorded the changes in the nature of organic P in alkaline extracts from gut content. Alkaline phosphatase activity was high in the alkaline midgut, but low in the hindgut and soil. Ferric iron (Fe3+) in the soil was reduced to ferrous iron (Fe2+) in the gut. The amount of Ca2+ was lower in the gut than in the soil. Iron reduction and the decrease of Ca2+ concentration in the gut would reduce P sorption. We think that the following effects are responsible for increased availability of P during the gut passage: alkaline extraction of soil organic matter; hydrolysis of organic phosphate esters with alkaline phosphatase; digestion by the resident microorganisms; and changes in the concentration of metal ions during gut passage. This study suggests that the feeding activities of humivorous larvae would affect the amount of soil P available to plant growth. [ABSTRACT FROM AUTHOR]

Abstract: Changes in the nature of the seed coat caused by gut passage are considered to be the proximate causes of changes in germination patterns. Modifications of seed coat permeability may be decisive in saline environments (e.g. Mediterranean wetlands), in which the response of the seed to osmotic stress, or its resistance to toxicity caused by some ions may be affected. We analysed how passage through a duck gut can change the response pattern of seeds of a Mediterranean helophyte Juncus subulatus to an experimental salinity gradient. Gut passage produced (1) a significant loss of seed viability (about 30%) across the whole salinity gradient and (2) no change in the intrinsic variability of the dormancy period or germination rate in J. subulatus seeds. However, J. subulatus seeds clearly have the potential to disperse via birds. We compare our results with those obtained previously for sympatric species of saline environments. [Copyright &y& Elsevier]