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1.
In Neotropical regions, fruit bats are among the most important components of the remaining fauna in disturbed landscapes. These relatively small-bodied bats are well-known dispersal agents for many small-seeded plant species, but are assumed to play a negligible role in the dispersal of large-seeded plants. We investigated the importance of the small tent-roosting bat Artibeus watsoni for dispersal of large seeds in the Sarapiquí Basin, Costa Rica. We registered at least 43 seed species > 8 mm beneath bat roosts, but a species accumulation curve suggests that this number would increase with further sampling. Samples collected beneath bat feeding roosts had, on average, 10 times more seeds and species than samples collected 5 m away from bat feeding roosts. This difference was generally smaller in small, disturbed forest patches. Species-specific abundance of seeds found beneath bat roosts was positively correlated with abundance of seedlings, suggesting that bat dispersal may influence seedling recruitment. Our study demonstrates a greater role of small frugivorous bats as dispersers of large seeds than previously thought, particularly in regions where populations of large-bodied seed dispersers have been reduced or extirpated by hunting.  相似文献   

2.
In the tropical forests of SE Asia, only a few studies have dealt with the role animal dispersal plays in early forest succession and rehabilitation, and a comparison of bird and bat dispersal is even rarer. We investigated seed dispersal by birds and bats in a successional area in the lowland dipterocarp forest of the Subic Watershed Forest Reserve (SWFR) in Luzon Island, Philippines. Using pairs of day and night traps, we collected seeds during 3 mo of wet season and 3 mo of dry season in a 1.2-ha study site. Bird-dispersed seeds predominated over those dispersed by bats in terms of both seed abundance and number of seed species. The most abundant endozoochorous seed species were significantly biased toward either bird or bat dispersal. Birds and bats appeared to compete more strongly for fruit resources during the dry season than during the wet season, and bats responded more to changes in the seasons than birds did. GLM analyses showed that the factor that had the strongest influence on overall seed distribution was the number of fleshy-fruited trees surrounding the traps, and that the distribution pattern of day-dispersed seeds was affected by more physical factors (number of trees, size of trees, presence of fleshy-fruited and conspecific trees) in the study site than the pattern of night-dispersed seeds were. Given that birds are the more important dispersers in the study site, restoration efforts in SWFR might benefit by focusing on attracting these dispersers into its degraded habitats.  相似文献   

3.
Seed dispersal and pollination by animals play a crucial role in the maintenance of forest ecosystems worldwide. Frugivorous bats are important pollen and seed dispersers in both the Palaeo- and Neotropics, and at least 300 plant species are known to rely on Old World fruit bats (Megachiroptera, Pteropodidae) for their propagation. However, rapid food transit times (generally less than 30 minutes) in frugivorous bats have been thought to limit their ability to disperse seeds to just a few tens of kilometres. Here we demonstrate regular daytime (greater than 12 hours) retention of food and viable fig seeds (Ficus, Moraceae) in the gut of the Old World fruit bat Cynopterus sphinx: a behaviour not previously reported for any frugivorous bat. Field observations indicate that this behaviour also occurs in other genera. Old World fruit bats are highly mobile and many species undertake considerable foraging and migration flights. Our findings indicate that Old World fruit bats have the potential to disperse small seeds hundreds of kilometres. This necessitates a reappraisal of their importance in transporting zoochorous seeds to remote areas and facilitating gene flow between isolated populations of plants, both within mainlands and across ocean barriers.  相似文献   

4.
The dispersal of Morus macroura seeds by two species of frugivorous bats ( Rousettus leschenaulti and Cynopterus sphinx ) was studied in a forest at Xishuangbanna Tropical Botanical Garden in Southwest China from March to May 2005. Feeding roosts were identified within 500 m around parent trees and the types and number of seed loads under each roost were recorded. We found feeding roost density decreased with increasing distance from the parent, but found no correlation between distance and seed deposition. The effect of bat digestion on seed germination was investigated, and we found that germination percentage of all treatments involving ingestion by bats was significantly lower than control seeds and some germination parameters of seeds from different treatments changed.  相似文献   

5.
Although fleshy fruits function primarily to attract seed dispersers, many animal‐dispersed fruits contain potentially toxic secondary metabolites. These metabolites can provide defense against seed predators and pathogens, but their effects on dispersers are still poorly understood. In some cases plants may experience a tradeoff, where the metabolites that provide fruit defense also reduce seed disperser preferences. In other cases the bioactivity of fruit secondary metabolites may be directed primarily at pests with no negative effects on seed‐dispersing vertebrates. We tested the effects of amides, a group of nitrogen‐based defensive compounds common in the plant genus Piper (Piperaceae), in interactions with the primary seed dispersers of Piper in the neotropics – fruit‐feeding bats in the genus Carollia (Phyllostomidae). In a series of flight cage experiments, pure amides and amide‐rich fruit extracts reduced the preferences of bats for Piper fruit, affecting both the bats’ initial choices to remove Piper infructescences and the proportion of fruit consumed from individual infructescences once they were removed. However, the effects of amides varied considerably among three species of Carollia and among the specific individual amides and extracts tested. Overall, our results support the hypothesis that plants experience a tradeoff between seed dispersal and fruit defense, but the strength of this tradeoff and the overall fitness consequences may depend strongly on ecological context.  相似文献   

6.
Seed dispersal, a key process in terrestrial landscapes, is increasingly important in the face of habitat fragmentation and global climate change. Seed dispersal is also notoriously difficult to characterize, especially in species rich and spatially complex tropical forests. We contrasted assemblages of biotically dispersed seeds collected from four sites using two methods: deposition into seed traps and interception by the capture of frugivorous birds. We also compared seed deposition and interception with local fruit production. Species accumulation curves for seeds deposited in seed traps began to level off sooner than curves for seeds collected from birds captured in mist nets, and extrapolation showed significantly greater estimated species richness for seeds collected from birds than for those deposited in traps. Assemblages from birds and from traps at each site were quite different, with an abundance‐based similarity index of 0.64; this dissimilarity increases if bat‐dispersed seeds are included in the analysis. Common bird‐dispersed species were retrieved from both mist‐netted birds and from seed traps, but numerous locally fruiting understory species were recovered only from birds. We conclude that the sampling of seeds carried by birds provides a valuable complement to other methods of studying seed dispersal in species‐rich tropical forests by revealing relationships between specific dispersers and their seed plants and by creating a more complete account of species diversity of seeds being transported at a given site.  相似文献   

7.
Despite considerable inter- and intraindividual variation in fruit and seed size in many plant species, researchers have given little attention to the relevance of the traits for primate fruit choice within a food plant species and its implications for tree regeneration. We studied feeding behavior and selectivity of olive baboons (Papio anubis) in the African locust bean (Parkia biglobosa, Mimosaceae), via direct observations of habituated groups and indirect evidence from leftovers of pods after feeding events. Olive baboons acted as both seed predators and dispersers for Parkia biglobosa. They fed on and destroyed unripe seeds, and swallowed intact ripe seeds when consuming mature fruit pulp. Predation rate was high, and only 10% of the seeds were dispersed. Predation and dispersal of seeds is linked to seed number and size. Digestible unripe seeds accounted for 10% of the unripe fruit mass, while indigestible ripe seeds made up 28% of the mature fruit mass. With these constraints, olive baboons increased food gain per fruit by selecting unripe pods containing a high number of large and heavy seeds. Consequently, only pods with fewer and smaller seeds remained for maturation. Thereafter, baboons fed on mature pods containing the smallest seeds, and exploited pods with more seeds to a greater extent than those with fewer seeds. Thus, fruits with small seeds and an intermediate seed number contributed the most to dispersal by baboons.  相似文献   

8.
Recent studies of new world parrots repeatedly document, with few exceptions, that parrots are wasteful and destructive predispersal seed predators that are unlikely to contribute towards pollination and seed dispersal. Few detailed studies, however, have assessed the contribution of African parrots to forest ecology by quantifying the potential net benefit of seed and flower predation by parrots for most tree species in their diet. Due to the incidence of pollen on the heads of Meyer’s Parrots when feeding on Leguminosae flowers and the dispersal of viable seeds to the ground during seed predation, we compared destruction rates, when feeding on pods, fruits and flowers, with dispersal rates of viable seeds to the ground and frequency of head contact with reproductive apparatus to estimate net benefit from Meyer’s Parrot feeding activity. Meyer’s Parrots were not implicated in endo‐ or epizoochory, but they dropped uneaten fruit pulp and seeds to the ground during feeding bouts, thus providing ripe, undamaged seeds to secondary seed dispersers. This link with forest recruitment was weak, as all tree species utilized by Meyer’s Parrots either had more significant primary dispersal agents or were primarily wind‐dispersed. In most cases, the negative effect of seed predation outweighed any positive effects in terms of dispersal, whereby almost three times more seeds were consumed or destroyed than were dispersed to the ground. Significantly, only Sclerocarya birrea caffra recorded marginal net dispersal benefit from utilization by Meyer’s Parrots. Due to low relative resource abundance and high destruction rate, feeding activity on Berchemia discolor may be significant enough to influence its spatial distribution and abundance. Utilization of flowers of Kigelia africana and Adansonia digitata by parrots likely had a significant negative impact on pollination. Feeding on Acacia nigrescens flowers, however, was potentially advantageous to their pollination. We conclude that Poicephalus parrots are net consumers of ripe, undamaged seeds and flowers, thus having an overall negative impact on forest recruitment in subtropical Africa.  相似文献   

9.
Neotropical fruit bats (family Phyllostomidae) facilitate forest regeneration on degraded lands by dispersing shrub and tree seeds. Accordingly, if fruit bats can be attracted to restoration sites, seed dispersal could be enhanced. We surveyed bat communities at 10 sites in southern Costa Rica to evaluate whether restoration treatments attracted more fruit bats if trees were planted on degraded farmlands in plantations or island configurations versus natural regeneration. We also compared the relative influence of tree cover at local and landscape spatial scales on bat abundances. We captured 68% more fruit bat individuals in tree plantations as in controls, whereas tree island plots were intermediate. Bat activity also responded to landscape tree cover within a 200‐m radius of restoration plots, with greater abundance but lower species richness in deforested landscapes. Fruit bat captures in controls and tree island plots declined with increasing landscape tree cover, but captures in plantations were relatively constant. Individual species responded differentially to tree cover measured at different spatial scales. We attribute restoration effects primarily to habitat structure rather than food resources because no planted trees produced fruits regularly eaten by bats. The magnitude of tree planting effects on fruit bats was less than previous studies have found for frugivorous birds, suggesting that bats may play a particularly important role in dispersing seeds in heavily deforested and naturally regenerating areas. Nonetheless, our results show that larger tree plantations in more intact landscapes are more likely to attract diverse fruit bats, potentially enhancing seed dispersal.  相似文献   

10.
从2005年3月到2006年5月,在中国科学院西双版纳热带植物园沟谷雨林保护区内研究了两种果蝠——棕果蝠(Rousettus leschenaulti)和犬蝠(Cynopterus sphinx)取食光叶桑(Morus macroura) 果实的行为、夜栖息地分布、散布种子方式及范围等。借助月光对果蝠的行为进行直接观察,发现它们的取食活动一般在天黑20~40 min开始,取食高峰发生在22: 00~22: 30 和23:00~23:30之间,这两个取食高峰期平均取食次数(平均值±标准误)为(13.5±2.5)和(15.0±2.3)次,最低的取食频率发生在19: 00~19: 30和20: 30~21: 00之间,分别取食(0.2±0.2)和(0.7±0.5)次。果蝠很少在母树上取食成熟的果实,相反它们用嘴叼下果实并携带到夜栖息地去进食,通常这些夜栖息地是具有密闭树冠、密集枝条的树种。夜栖息地在母树周围的分布根据环境中适合它们栖息的树种和分布而决定,不同母树周围其夜栖息地分布具有非常大的变异与空间异质性。钝叶榕(Ficus curtipes)、铁力木(Mesua ferrea) 和糖胶树(Alstonia scholaris) 是果蝠最喜爱的夜栖息地。在同样的情况下,尽管需要飞行更远的距离,两种果蝠都比较喜欢寻找具有许多枝条和小枝并且有复杂树冠的树木作为夜栖息地。两种果蝠取食光叶桑果实时,一部分种子通过消化道消化后被排泄出来,另外的一部分伴随着咀嚼后的果渣被吐出来,通过这两种方式,散布了大量的种子,再加上在飞行中也有排泄的习性,它们传播的种子在空间上更广泛。  相似文献   

11.
Summary This paper describes the nightly and seasonal production of ripe fruit by Piper amalago (Piperaceae), a patchily distributed, bat-dispersed forest shrub, at Parque Nacional Santa Rosa, Costa Rica. Phenological observations over several years indicate that individuals produce a low (usually 1–3) and variable number of ripe fruit each night for 3–4 wks in the early wet season (June and July). Observations of the disappearance rates of marked fruits and fruit manipulation experiments indicate that fruit removal probabilities are high (often nearly 1.0) and independent of nightly and seasonal ripe fruit crop size. Data from previous feeding and foraging studies of the bat Carollia perspicillata (Phyllostomidae) are used to estimate the mobility of P. amalago's seeds. Most seeds (>90%) are deposited 50 m from parent plants under night feeding roosts. Relatively few seeds move >300 m, and movements this long are more likely to occur early and late in the fruiting season when bats change feeding sites more frequently. Seed experiments indicate that P. amalago seedling establishment probabilities are higher in light gaps than under forest canopy. The dispersal quality (sensu McKey 1975) of P. amalago's chiropteran seed dispersers is directly proportional to the number of seeds they excrete in actual or incipient light gaps.  相似文献   

12.
Most predictions of vegetation responses to anthropogenic climate change over the next 100 yr are based on plant physiological tolerances and do not account for the ability of plant species to migrate over the distances required in the time available, or the impact of habitat fragmentation on this ability. This review assesses the maximum routine dispersal distances achievable in tropical East Asia and their vulnerability to human impacts. Estimates for various plant–vector combinations range from < 10 m, for species dispersed by ants or mechanical means, to > 10 km for some species dispersed by wind (tiny seeds), water, fruit pigeons, large fruit bats (tiny seeds), elephants, rhinoceroses, and people. Most plant species probably have maximum dispersal distances in the 100–1000 m range, but the widespread, canopy-dominant Dipterocarpaceae and Fagaceae are normally dispersed < 100 m. Large fruit bats and fruit pigeons are particularly important for long-distance dispersal in fragmented landscapes and should be protected from hunting. The maximum seed dispersal distances estimated in this study are potentially sufficient for many plant species to track temperature changes in steep topography, but are far too small for a significant role in mitigating climate change impacts in the lowlands, where temperature and rainfall gradients are much more shallow.  相似文献   

13.
Large vertebrates are important elements of mutualistic interactions and provide positive impacts on plant population and community dynamics. Despite the increasing interest on vertebrate frugivory we are still not able to disentangle the real contribution of seed dispersal to Neotropical forest functioning. Consuming fruits does not imply effective seed dispersal and many variables, such as seed size and animal diet, may influence the outcome of plant-animal interactions. Here, we performed a comprehensive literature search on seed dispersal by Neotropical vertebrates (with a focus on primates) to closely approach their role as seed dispersers, hypothesizing frugivory degree and seed size as main drivers of fruit handling behavior and diversity of dispersed seeds. We found that the great majority of seeds manipulated by Neotropical primates, with exception to the seed predators pitheciins, were swallowed and passed intact through their gut. Larger seeds (>12 mm) tended of being ingested exclusively by primates and other large vertebrates, such as tapirs and peccaries. Furthermore, primate feeding guild had a great influence on the richness and sizes of seeds dispersed, as primarily frugivores dispersed more species and had higher probabilities of ingesting larger seeds when compared to other feeding guilds. Organizing available knowledge and filling the main knowledge gaps allowed us to validate common sense assumptions and ultimately draw new conclusions about the role played by primates together with other major frugivores in Neotropical forests.  相似文献   

14.
The spread of invasive alien plants into natural habitats is of growing global concern. Several studies have investigated the role that avian frugivores play in the dispersal of these seeds and their effects on germination success. Fruit bats have however received little attention as important dispersal agents of invasive alien plants, despite their recognized role as long distance dispersal agents of various native flora. We investigated whether Wahlberg’s epauletted fruit bats, Epomophorus wahlbergi, would positively influence the germination of seeds of invasive alien plants. These fruit bats were fed fruits of four invasive alien plant species—Psidium guajava, Melia azedarach, Eriobotrya japonica, and Morus alba. Epomophorus wahlbergi were able to process more fruit per gram body mass than birds have been observed to do. Spat and de-pulped control seeds had similar germination success and germinated at approximately the same time for most species. While seeds retained in whole fruit had significantly less germination success than spat seeds for all species, except M. azedarach, they mostly germinated at approximately the same time. Epomophorus wahlbergi can swallow small seeds (< 2 mm), while seeds larger than this are generally spat out. Large fruit are usually carried away to feeding roosts where seeds are dropped, thereby dispersing seeds and fruits which are too large for some bird species to ingest. Epomophorus wahlbergi should not be underestimated as dispersers of these invasive alien plants as they consume proportionally large amounts (0.62 ± 0.09 to 0.99 ± 0.11 g.g−1 body mass) of fruit, except for M. azedarach, and positively affect their seed germination rates.  相似文献   

15.
Understanding the mutualisms between frugivores and plants is essential for developing successful forest management and conservation strategies, especially in tropical rainforests where the majority of plants are dispersed by animals. Gibbons are among the most effective seed dispersers in South East Asia's tropical forests, but are also one of the highly threatened arboreal mammals in the region. Here we studied the seed dispersal of the Pacific walnut (Dracontomelon dao), a canopy tree which produces fruit that are common in the diet of the endangered southern yellow-cheeked crested gibbon (Nomascus gabriellae). We found that gibbons were the most effective disperser for this species; they consumed approximately 45% of the fruit crop, which was four times more than that consumed by macaques – the only other legitimate disperser. Gibbons tracked the temporal (but not spatial) abundance of ripe fruits, indicating this fruit was a preferred species for the gibbon. Both gibbons and macaques dispersed the majority (>90%) of the seeds at least 20 m away from parent crowns, with mean dispersal distances by gibbons measuring 179.3 ± 98.0 m (range: 4–425 m). Seeds defecated by gibbons germinated quicker and at greater rates than seeds spat by macaques, or in undispersed fruits. Gibbon-dispersed seeds were also more likely to be removed by unknown seed predators or unknown secondary dispersers. Overall, gibbons play a key role in the regeneration of the Pacific walnut. Our findings have significant implications both for the management of the Pacific walnut tree dominating tropical rainforest as well as the reintroduction program of the Southern yellow-cheeked crested gibbon.  相似文献   

16.
17.
To assess the impact of bats on seed dispersal in a tropical mature forest (Nouragues, French Guiana), we conducted a bat exclusion experiment and tested the hypotheses that an artificial reduction in the abundance of bats would result in: (1) a decrease in seed species diversity, at the community level; and (2) an increase in seed limitation (a failure of seeds to reach all suitable sites for germination) at the species level. Seed rain was sampled in two contiguous forest plots for a total of 120 d, using 49 seed traps (1 m2) arranged in 7 × 7 grids and spaced at 5-m intervals. Using mist nets, bat activity was reduced in one forest plot for a total of 60 nights. Thirty-nine plant species, or species groups, likely to be consumed and dispersed by bats, were collected within a total sample of 50,063 seeds. The overall seed rain was dominated by epiphytic Araceae and Cyclanthaceae (83.3%) and tree species within the genera Cecropia and Ficus (16.0%). Seeds from bat-dispersed shrubs and treelets ( Piper , Solanum , and Vismia ) were relatively rare (0.7%). The bat exclusion resulted in a 30.5 percent reduction in seed species richness and increased seed limitation for most of the species sampled. Seed limitation was caused mainly by a reduced seed rain (seed source limitation) rather than a decrease in seed dispersal uniformity (seed dispersal limitation). Therefore, bat-dispersed plants with low seed production are likely to be particularly affected by a decline in bat abundance, as a result of anthropogenic change.  相似文献   

18.
Tracking the dispersal of seeds by fruit‐eating animals in tropical rain forests is crucial to further our understanding of plant–frugivore interactions and their impacts upon forest regeneration and plant population dynamics. We tested the feasibility of tracking bat‐dispersed seeds in a Philippine lowland rain forest with the help of fluorescent pigment. The powder was mixed with acetone and sprayed to ripe fruits of fig trees, i.e., Ficus septica and F. variegata. During nightly monitoring using a hand‐held ultraviolet lamp bat deposits (seed‐containing spat outs and feces) could successfully be detected. Distances and directions of deposit sites to the focal trees were recorded and seed shadow areas were analyzed. Bats dispersed most of the seeds less than 50 m away from the parent plants resulting in seed shadow areas < 0.30 ha in size. An in situ fruit preference experiment showed that fluorescent powder is unlikely to deter bats from feeding on ripe figs. In conclusion, the technique is simple, inexpensive, noninvasive, applicable to different fields of research and allows one to follow the fate of seeds from known sources.  相似文献   

19.
Few Neotropical plant species seem to depend on the same animal type both for pollination and seed dispersal, and the known instances refer mostly to birds as the agents in these two phases of a plant reproductive cycle. Dyssochroma viridiflorum (Solanaceae), an epiphyte endemic to the Atlantic rainforest in south-eastern Brazil, was found to be visited by phyllostomid bats for nectar as well as for fruits, with the pollination and seed dispersal of the plant ensured by these flying mammals. The greenish flowers open at night and are visited by the nectar-feeding bat Glossophaga soricina, whereas the yellowish-white fruits are consumed by two species of fruit-eating bats, Carollia perspicillata and Sturnira lilium. Only clinging visits, an uncommon behavioural pattern for glossophagine bats while feeding on flowers, were recorded. The small seeds of D. viridiflorum are swallowed along with the fruit pulp and later defecated on the bats' flying pathways. It is suggested that species of Dyssochroma and two other solanaceous bat-pollinated genera, Merinthopodium and Trianaea, form a derived and bat-dependent clade within the Juanulloeae.  相似文献   

20.
We examined seed dispersal by bats and birds in four habitats of the Selva Lacandona tropical rain forest region, Chiapas, Mexico. The four habitats represented a disturbance gradient: active cornfield, ten-year-old abandoned cornfield, cacao plantation, and forest. Using seed traps examined before sunrise (0400 h) and before sunset (1800 h), we compared volant vertebrate seed dispersal, assuming that seeds found at the end of the night were dispersed by bats and those found at the end of the day were dispersed by birds. We did not find seeds from other frugivores such as monkeys or opossums. In all habitats bats dispersed more seeds than birds. In most months bats also dispersed more seeds than birds, except in December when no seeds were found in the traps. Bats also consistently dispersed more species of seeds than birds, although a x2 comparison showed differences not to be significant. Fifty percent of the species represented in the dispersed seeds in all habitats were pioneer species. Cecropia seeds represented a high percentage (up to 87% of those dispersed by bats and up to 83% by birds) of dispersed seeds that fell in our traps. The influence of bats and birds on secondary successional processes is likely to be fundamental for the establishment of vegetation. Since bats dispersed more seeds than birds (primarily to disturbed areas and consisting primarily of pioneer species), they are likely to play an important role in successional and restoration processes among habitats as structurally and vegetationally different as cornfields, old fields, cacao plantations, and forest.  相似文献   

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