Home About us Contact
|
Home About us Contact | ||
|
|
||
Frugivores
Kinds of Frugivores Terms modified by Frugivores Selected AbstractsDependence of broad-scale geographical variation in fleshy-fruited plant species richness on disperser bird species richnessGLOBAL ECOLOGY, Issue 4 2004Ana L. Márquez ABSTRACT Aim, We analysed the interdependence of avian frugivore- and fruited plant-species richness at the scale of major river basins across Europe, taking into account several environmental factors along different spatial gradients. Location, Continental Europe and the British Isles. Methods, We focused on wintering birds and autumn/winter fruiting plants, and used major river basins as geographical units and Structural Equation Modelling as the principal analytical tool. Results, The statistical influence of disperser species richness on fleshy-fruited plant species richness is roughly double that of the reverse. Broad-scale variation in frugivore richness is more dependent on environmental factors than on fruited plant richness. However, the influence of disperser richness on plant richness is four times higher than the influence of environmental factors. Environmental influences on both birds and plants are greater than purely spatial influences. Main conclusions, Our results are interpreted as indicating that biotic dispersal of fruits strongly affects broad-scale geographical trends of fleshy-fruited plant species richness, whereas richness of fruited plants moderately affects frugivore richness. [source] Context-dependency of a complex fruit,frugivore mutualism: temporal variation in crop size and neighborhood effectsOIKOS, Issue 3 2010Soumya Prasad The quantity of fruit consumed by dispersers is highly variable among individuals within plant populations. The outcome of such selection operated by frugivores has been examined mostly with respect to changing spatial contexts. The influence of varying temporal contexts on frugivore choice, and their possible demographic and evolutionary consequences is poorly understood. We examined if temporal variation in fruit availability across a hierarchy of nested temporal levels (interannual, intraseasonal, 120 h, 24 h) altered frugivore choice for a complex seed dispersal system in dry tropical forests of southern India. The interactions between Phyllanthus emblica and its primary disperser (ruminants) was mediated by another frugivore (a primate), which made large quantities of fruit available on the ground to ruminants. The direction and strength of crop size and neighborhood effects on this interaction varied with changing temporal contexts. Fruit availability was higher in the first of the two study years, and at the start of the season in both years. Fruit persistence on trees, determined by primate foraging, was influenced by crop size and conspecific neighborhood densities only in the high fruit availability year. Fruit removal by ruminants was influenced by crop size in both years and neighborhood densities only in the high availability year. In both years, these effects were stronger at the start of the season. Intraseasonal reduction in fruit availability diminished inequalities in fruit removal by ruminants and the influence of crop size and fruiting neighborhoods. All trees were not equally attractive to frugivores in a P. emblica population at all points of time. Temporal asymmetry in frugivore-mediated selection could reduce potential for co-evolution between frugivores and plants by diluting selective pressures. Inter-dependencies formed between disparate animal consumers can add additional levels of complexity to plant,frugivore mutualistic networks and have potential reproductive consequences for specific individuals within populations. [source] Gap-crossing movements predict species occupancy in Amazonian forest fragmentsOIKOS, Issue 2 2009Alexander C. Lees In fragmented landscapes, species persistence within isolated habitat patches is governed by a myriad of species life-history, habitat patch and landscape characteristics. We investigated the inter-specific variation in non-forest gap-crossing abilities of an entire tropical forest-dependent avifauna. We then related this measure of dispersal ability to species life-history characteristics and occupancy data from 31 variable-sized forest patches sampled within the same fragmented forest landscape. A total of 5436 gap-crossing movements of 231 forest-dependent bird species were observed across ten linear forest gaps of varying widths, adjacent to large areas of undisturbed forest. Species persistence in isolated fragments was strongly linked to gap-crossing ability. The most capable gap-crossers were medium to large-bodied species in the large insectivore, frugivore and granivore guilds, matching the most prevalent subset of species in small forest patches. However, some competent gap-crossing species failed to occur in small patches, and minimum forest-patch area requirements were more important in determining patch occupancy for these species. Narrow forest gaps (4,70 m) created by roads and power-lines may become territory boundaries, thereby eliminating home-range gap-crossing movements for many forest species, but permit rarer dispersal events. Wider gaps (>70 m) may inhibit gap-crossing behaviour for all but the most vagile species. Although patch size and quality may be the most important factors in structuring species assemblages in forest fragments, our results show that the degree of patch isolation and permeability of the surrounding matrix also explain which species can persist in forest isolates. Reducing the number and width of forest-dividing gaps; maintaining and/or creating forest corridors and increasing matrix permeability through the creation and maintenance of ,stepping-stone' structures will maximise the species retention in fragmented tropical forest landscapes. [source] A neutral-niche theory of nestedness in mutualistic networksOIKOS, Issue 11 2008Abhay Krishna Recently, there has been a vigorous interest in community ecology about the structure of mutualistic networks and its importance for species persistence and coevolution. However, the mechanisms shaping mutualistic networks have been rarely explored. Here we extend for the first time the neutral theory of biodiversity to a multi trophic system. We focus on nestedness, a distinctive pattern of mutualistic community assembly showing two characteristics, namely, asymmetrical specialization (specialists interacting with generalists) and a generalist core (generalists interacting with generalists). We investigate the importance of relative species abundance (RSA) for the nested assembly of plant,animal mutualistic networks. Our results show that neutral mutualistic communities give rise to networks considerably more nested than real communities. RSA explains 60,70% of nested patterns in two real communities studied here, while 30,40% of nestedness is still unexplained. The nested pattern in real communities is better explained when we introduce interaction-specific species traits such as forbidden links and intensity of dependence (relative importance of fruits for the diet of a frugivore) in our analysis. The fact that neutral mutualistic communities exhibit a perfectly nested structure and do not show a random or compartmentalized structure, underlines the importance of RSA in the assembly of mutualistic networks. [source] Digestion in the common marmoset (Callithrix jacchus), a gummivore,frugivoreAMERICAN JOURNAL OF PRIMATOLOGY, Issue 12 2009Michael L. Power Abstract Wild common marmosets (Callithrix jacchus) feed on fruits, insects, and gums, all of which provide different digestive challenges. Much of the ingested mass of fruits consists of seeds. In general, seeds represent indigestible bulk to marmosets and could inhibit feeding if they are not eliminated rapidly. In contrast, gums are ,-linked polysaccharides that require microbial fermentation. Their digestion would benefit from an extended residence time within the gut. Earlier research found that mean retention time (MRT) for a liquid digestive marker (cobalt EDTA) was significantly longer than MRT for a particulate marker (chromium-mordanted fiber), suggesting that common marmosets preferentially retain liquid digesta. We conducted two four-day-long digestion trials on 13 individually housed adult common marmosets fed a single-item, purified diet in order to examine the relations among MRT of cobalt EDTA and chromium-mordanted fiber, food dry matter intake (DMI), and apparent digestibility of dry matter (ADDM). We compared the MRT values with the data from the previous study mentioned above and a study using polystyrene beads. There were no significant correlations among MRT, ADDM, or DMI, although increases in DMI between trials were associated with decreases in MRT. ADDM was consistent within individuals between trials; but the mean values ranged from 75.0 to 83.4% among individuals. We found no difference in MRT between the liquid (17.5±1.6,hr) and particulate (17.9±1.4 hr) markers. Although these values were not significantly different than found previously, the MRT for chromium-mordanted fiber tended to be longer. This probably reflects the relatively small size of the chromium-mordanted fiber particles used in this study. An inverse relationship between particle size and MRT was evident; the mean MRT of polysterene beads, the largest marker, was only 8.3±1.5,hr. Marmosets appear to retain liquids and small particles within the gut longer than large particles. Am. J. Primatol. 71:957,963, 2009. © 2009 Wiley-Liss, Inc. [source] Consequences of southern cassowary (Casuarius casuarius, L.) gut passage and deposition pattern on the germination of rainforest seedsAUSTRAL ECOLOGY, Issue 3 2010MATT G. BRADFORD Abstract In Australia's tropical rainforests the endangered southern cassowary, Casuarius casuarius, L., is the largest native frugivore and many plant species, because of the size of their fruits or seeds, are thought to be largely dependent on cassowaries for their dispersal. In this study we asked whether the contribution of cassowaries to plant recruitment extends beyond removing seeds from the vicinity of the parent. To do this we conducted germination trials involving 17 rainforest plant species to test whether cassowary consumption and seed deposition pattern alter germination probability or time to germination. Twenty-four per cent of species showed changed germination probabilities, with one species showing no germination without cassowary consumption, and 35% showed changed time to germination. However these differences did not translate into any significant effects when considered across all species. We examined gut scarification, fruit pulp removal (de-inhibition) and deposition in faecal material as mechanisms for changing germination success; each contributed to the changed success of individual species. There was a negative effect of seed clumping on five species. We conclude that cassowary consumption can modify germination performance in a minority of rainforest plants and that the effect is generally positive. Although the effect on large seeded species was small it is most likely to be important as the cassowary is the only animal in Australia able to internally process large numbers of these seeds. [source] Frugivory and seed dispersal by foxes in relation to mammalian prey abundance in a semiarid thornscrubAUSTRAL ECOLOGY, Issue 7 2005SERGIO I. SILVA Abstract We examine the role of the native fox, Pseudalopex culpaeus, as a frugivore and seed disperser in a semiarid thornscrub of Chile. We quantified the fruit and animal components in its diet versus the availability of fruits and small mammals in the field over a 2-year period (January 1998 through February 2000). We tested the legitimacy and effectiveness of foxes as dispersers by quantifying the percentages of seed viability and of germination of seeds that passed through fox gut versus those picked from plants. We also studied their efficiency as dispersers, monitoring the fate of seeds in faeces placed in the field. The highest frequencies of fruit consumption by foxes were observed when abundances of small mammal prey were <6 individuals per hectare, regardless of fruit abundance in the field. Thus, foxes consumed fruits as a supplementary food resource. Based on 326 faeces, the total number of fruits consumed was about 34 000 over the 2-year study period, and fruits from the alien shrub Schinus molle represented 98% of that total, with the native Porlieria chilensis a distant second. Germination and viability of defecated seeds of P. chilensis were reduced by 66% and 48%, respectively, in comparison to controls. In contrast, germination of seeds of S. molle increased by 50% and no effect on viability was observed. With regard to P. chilensis, foxes were legitimate (they defecated viable seeds), but ineffective (seeds in faeces had lower germination than those taken directly from parental plants and there was no seedling establishment in the field) and inefficient dispersers (seeds in faeces were deposited on microhabitats hostile to seed germination and seedling establishment). However, with regard to S. molle, foxes were legitimate, effective (seeds in faeces had higher germination than those taken directly from parental plants; there was germination but no establishment in the field), and efficient dispersers (over 41% of seeds were deposited on safe microsites). Thus, a native fox may be contributing to the spread of an alien shrub, co-opting existing community processes. [source] Early fate of Myristica hypargyraea seeds dispersed by Ducula pacifica in Tonga, Western PolynesiaAUSTRAL ECOLOGY, Issue 4 2005HAYLEY J. MEEHAN Abstract Although pigeons from the genus Ducula are considered among the best avian dispersers of large seeds in Asia and the Pacific, little has been documented on their role. The early fate of dispersed and undispersed seeds of the large-seeded tree Myristica hypargyraea A. Gray was studied in order to understand the advantage of seed dispersal by the Pacific Pigeon, Ducula pacifica Gmelin in Tonga. Frequency of visits by frugivores to fruiting trees and dispersal distance of seeds were measured. Pre-dispersal vertebrate seed predation was assessed, then post-dispersal predation was measured over 160 days. Overall, pre-dispersal seed predation by parrots was low but variable among trees sampled. Most seeds (54.7%) in the study area were estimated to be dispersed by D. pacifica; 79.7% of those ingested were expelled directly beneath conspecific fruiting crowns, 20% were dispersed locally and <,0.3% were dispersed more than 300 m into a different forest type. Flying foxes (Pteropus tonganus Quoy and Gaimard) dispersed very few seeds (0.7%) and all were dropped below fruiting crowns. Between 4% and 39% of dispersed and undispersed seeds were still viable, or had established seedlings after 160 days. Most seeds had been removed or killed by rats, and seed survival was highest for locally dispersed seeds (approx. 20 m from source trees and within the M. hypargyraea forest). Although D. pacifica was the only frugivore observed to disperse seeds into this higher zone of survival, overall they did not confer a great advantage to seed survival since significant numbers of seeds/seedlings also persisted under fruiting crowns (27% under crowns compared with 39% locally dispersed). Nevertheless, D. pacifica was the only vector by which seeds were regularly moved within the M. hypargyraea forest and over longer distances, and hence, D. pacifica still plays a significant role in the regeneration of M. hypargyraea. [source] Phenological patterns in monsoon rainforests in the Northern Territory, AustraliaAUSTRAL ECOLOGY, Issue 5 2002Christine Susanne Bach Abstract Monsoon rainforests occur as scattered patches within a landscape dominated by eucalypt savannas across the wet,dry tropics of northern Australia. This study formed part of a larger project that investigated the interactions between frugivores and monsoon rainforest patches in the Top End of the Northern Territory. Phenological patterns in a set of 12 wet monsoon forests (WMF) and four dry monsoon forests (DMF) were examined by monitoring individuals of more than 100 species over 30 months. Phenological patterns of both WMF and DMF were closely related to the strongly seasonal climate. Leaf flush occurred before the onset of the wet season in WMF, and coincided with the onset of the wet in DMF. Major flowering peaks coincided with leaf flush in both forest types. Fruiting was concentrated in the wet season in both forest types, but fruiting peaks of WMF and DMF were separated by 3,4 months. Variations in fruiting patterns among forest types, patches, seasons and groupings of plant species (based on life form and ecological positioning) provide a mosaic of food resources for frugivores. This has important implications for the conservation and maintenance of the frugivore,rainforest system in northern Australia. [source] Fig-eating by vertebrate frugivores: a global reviewBIOLOGICAL REVIEWS, Issue 4 2001MIKE SHANAHAN ABSTRACT The consumption of figs (the fruit of Ficus spp.; Moraceae) by vertebrates is reviewed using data from the literature, unpublished accounts and new field data from Borneo and Hong Kong. Records of frugivory from over 75 countries are presented for 260 Ficus species (approximately 30% of described species). Explanations are presented for geographical and taxonomic gaps in the otherwise extensive literature. In addition to a small number of reptiles and fishes, 1274 bird and mammal species in 523 genera and 92 families are known to eat figs. In terms of the number of species and genera of fig-eaters and the number of fig species eaten we identify the avian families interacting most with Ficus to be Columbidae, Psittacidae, Pycnonotidae, Bucerotidae, Sturnidae and Lybiidae. Among mammals, the major fig-eating families are Pteropodidae, Cercopithecidae, Sciuridae, Phyllostomidae and Cebidae. We assess the role these and other frugivores play in Ficus seed dispersal and identify fig-specialists. In most, but not all, cases fig specialists provide effective seed dispersal services to the Ficus species on which they feed. The diversity of fig-eaters is explained with respect to fig design and nutrient content, phenology of fig ripening and the diversity of fig presentation. Whilst at a gross level there exists considerable overlap between birds, arboreal mammals and fruit bats with regard to the fig species they consume, closer analysis, based on evidence from across the tropics, suggests that discrete guilds of Ficus species differentially attract subsets of sympatric frugivore communities. This dispersal guild structure is determined by interspecific differences in fig design and presentation. Throughout our examination of the fig-frugivore interaction we consider phylogenetic factors and make comparisons between large-scale biogeographical regions. Our dataset supports previous claims that Ficus is the most important plant genus for tropical frugivores. We explore the concept of figs as keystone resources and suggest criteria for future investigations of their dietary importance. Finally, fully referenced lists of frugivores recorded at each Ficus species and of Ficus species in the diet of each frugivore are presented as online appendices. In situations where ecological information is incomplete or its retrieval is impractical, this valuable resource will assist conservationists in evaluating the role of figs or their frugivores in tropical forest sites. [source] The role of fruit traits of bird-dispersed plants in invasiveness and weed risk assessmentDIVERSITY AND DISTRIBUTIONS, Issue 6 2009Carl R. Gosper Abstract Aim, Birds play a major role in the dispersal of seeds of many fleshy-fruited invasive plants. The fruits that birds choose to consume are influenced by fruit traits. However, little is known of how the traits of invasive plant fruits contribute to invasiveness or to their use by frugivores. We aim to gain a greater understanding of these relationships to improve invasive plant management. Location, South-east Queensland, Australia. Methods, We measure a variety of fruit morphology, pulp nutrient and phenology traits of a suite of bird-dispersed alien plants. Frugivore richness of these aliens was derived from the literature. Using regressions and multivariate methods, we investigate relationships between fruit traits, frugivore richness and invasiveness. Results, Plant invasiveness was negatively correlated to fruit size, and all highly invasive species had quite similar fruit morphology [smaller fruits, seeds of intermediate size and few (< 10) seeds per fruit]. Lower pulp water was the only pulp nutrient trait associated with invasiveness. There were strong positive relationships between the diversity of bird frugivores and plant invasiveness, and in the diversity of bird frugivores in the study region and another part of the plants' alien range. Main conclusions, Our results suggest that weed risk assessments (WRA) and predictions of invasive success for bird-dispersed plants can be improved. Scoring criteria for WRA regarding fruit size would need to be system-specific, depending on the fruit-processing capabilities of local frugivores. Frugivore richness could be quantified in the plant's natural range, its invasive range elsewhere, or predictions made based on functionally similar fruits. [source] Conservation value of degraded habitats for forest birds in southern Peninsular MalaysiaDIVERSITY AND DISTRIBUTIONS, Issue 5 2006Kelvin S.-H. ABSTRACT Clearance of tropical forest for agricultural purposes is generally assumed to seriously threaten the survival of forest species. In this study, we quantified the conservation value, for forest bird species, of three degraded habitat types in Peninsular Malaysia, namely rubber tree plantations, oil palm plantations, and open areas. We surveyed these degraded habitats using point counts to estimate their forest bird species richness and abundance. We assessed whether richness, abundance, and activities of different avian dietary groups (i.e. insectivores and frugivores) varied among the habitats. We identified the critical habitat elements that accounted for the distribution of forest avifauna in these degraded habitats. Our results showed that these habitats harboured a moderate fraction of forest avifauna (approximately 46,76 species) and their functions were complementary (i.e. rubber tree plantations for moving; open habitats for perching; shrubs in oil palm plantations for foraging). In terms of species richness and abundance, rubber tree plantations were more important than oil palm plantations and open habitats. The relatively high species richness of this agricultural landscape was partly due to the contiguity of our study areas with extensive forest areas. Forecasts of forest-species presence under various canopy cover scenarios suggest that leaving isolated trees among non-arboreal crops could greatly attract relatively tolerant species that require tree canopy. The conservation value of degraded habitats in agricultural landscapes seems to depend on factors such as the type of crops planted and distance to primary forest remnants. [source] Fragmentation, habitat composition and the dispersal/predation balance in interactions between the Mediterranean myrtle and avian frugivoresECOGRAPHY, Issue 1 2010Juan P. González-Varo Human-induced fragmentation and disturbance of natural habitats can shift abundance and composition of frugivore assemblages, which may alter patterns of frugivory and seed dispersal. However, despite their relevance to the functioning of ecosystems, plant-frugivore interactions in fragmented areas have been to date poorly studied. I investigated spatial variation of avian frugivore assemblages and fruit removal by dispersers and predators from Mediterranean myrtle shrubs (Myrtus communis) in relation to the degree of fragmentation and habitat features of nine woodland patches (72 plants). The study was conducted within the chronically fragmented landscape of the Guadalquivir Valley (SW Spain), characterized by ~1% of woodland cover. Results showed that the abundance and composition of the disperser guild was not affected by fragmentation, habitat features or geographical location. However, individual species and groups of resident/migrant birds responded differently: whereas resident dispersers were more abundant in large patches, wintering dispersers were more abundant in fruit-rich patches. Predator abundances were similar between patches, although the guild composition shifted with fragmentation. The proportion of myrtle fruits consumed by dispersers and predators varied greatly between patches, but did not depend on bird abundances. The geographical location of patches determined the presence or absence of interactions between myrtles and seed predators (six predated and three non-predated patches), a fact that greatly influenced fruit dispersal success. Moreover, predation rates were lower (and dispersal rates higher) in large patches with fruit-poor heterospecific environments (i.e. dominated by myrtle). Predator satiation and a higher preference for heterospecific fruits by dispersers may explain these patterns. These results show that 1) the frugivore assemblage in warm Mediterranean lowlands is mostly composed of fragmentation-tolerant species that respond differently to landscape changes; and 2) that the feeding behaviour of both dispersers and predators influenced by local fruit availability may be of great importance for interpreting patterns of frugivory throughout the study area. [source] Nutritional consequences of a change in diet from native to agricultural fruits for the Samoan fruit batECOGRAPHY, Issue 4 2000Suzanne L. Nelson The Samoan fruit bat Pteropus samoensis Peak, an endemic flying fox that inhabits the Samoan archipelago, prefers to forage on native fruit species. This species has recently been subjected to extreme population threats including hunting and severe storms, as well as large-scale habitat degradation. If habitat destruction continues at its present rate, P. samoensis may be forced to forage more within an agricultural matrix. In this study, we analyzed sixteen species of native fruits and four species of agricultural fruits for five organic components and eight minerals to test whether native fruits provided a higher quality diet or more varied diet than agricultural fruits. Within native fruits, we also focused on four species of figs, because these fruits are often considered an important food item for tropical frugivores. Overall, native fruits provided more variation and had higher average values for several nutrients than agricultural fruits. Native fruits were especially high in biologically important minerals (calcium, iron, and sodium), and provided up to 5 times more calcium, 10.5 times more iron, and 8 times more sodium than agricultural fruits. Figs were found to be an especially rich source of many nutrients, particularly for calcium. Thus. P. samoensis. a sequential specialist, may be better able to adjust its diet to obtain higher levels of minerals when consuming a variety of native fruits than when restricted to the consumption of only agricultural fruits. These findings suggest a need to preserve native habitat and to create parks to sustain the long term health and viability of P. samoensis. [source] Foraging by fearful frugivores: combined effect of fruit ripening and predation riskFUNCTIONAL ECOLOGY, Issue 6 2006J. M. FEDRIANI Summary 1Plant defensive compounds and predation risk are main determinants of herbivore foraging, though empirical studies have seldom measured the combined effects of these two factors. By considering the interaction between the herb Helleborus foetidus and its main fruit and seed predator, the Wood Mouse Apodemus sylvaticus, we evaluated whether the defensive role against seed predators of compounds present in H. foetidus unripe fruits holds across a micro-landscape that differs in foraging costs (i.e. predation risk). 2First, we used standardized food patches that simulated fruiting H. foetidus plants to ascertain fruit preferences of captive mice. Then, by means of field experiments, we assessed the combined effects of fruit ripening and predation risk on foraging by free-ranging mice. 3Captive mice avoided plants with unripe fruit and avoided consuming unripe fruits within a particular plant. Free-ranging mice also avoided unripe fruits in safe microhabitats (rocky substrate), but not in risky microhabitats (bare ground) where few fruits were consumed. This unexpected result may be driven by predation risk experienced by mice foraging on H. foetidus fruits, and/or plant defensive compounds acting in a dose-dependent manner. 4Frugivorous mice responded to both chemical defences present in unripe H. foetidus fruits as well as to predation cost though such response was sequential. Plant defence compounds appeared to play a part in mouse foraging only after mice selected low predation risk microhabitats. 5Our study indicates that both digestive and ecological factors influence foraging decisions, which in turn affects pressures exerted by herbivores on plant populations. [source] Assessing the benefits of frugivory for seed germination: the importance of the deinhibition effectFUNCTIONAL ECOLOGY, Issue 1 2006A. W. ROBERTSON Summary 1Many studies have examined the effects of frugivores on the germination of seeds of fleshy fruited plants. However, three key issues are rarely addressed: the need to measure germination of seeds in intact fruits; the effect of germination conditions on results; and the distinction between dead vs dormant seeds. 2A literature review including 51 plant species from 28 families found that the often-measured scarification effect (germination of bird-defecated vs hand-cleaned seeds) is significantly smaller than the rarely-measured deinhibition effect (germination of hand-cleaned seeds vs those in intact fruits). 3Both the literature review and new experimental data show that germination conditions affect germination. In particular, seeds in intact fruits have much lower germination percentages in Petri dishes than in the field. Poor germination from intact fruits in Petri dishes may be an artefact. 4A field experiment with three New Zealand species showed variable effects of non-removal of the fruit pericarp. The retention of the pericarp had no effect on germination in Nestegis cunninghamii; increased the proportion of seeds entering dormancy in Melicytus lanceolatus; and greatly increased seed mortality in Pennantia corymbosa. 5Germination experiments must be designed carefully to evaluate accurately the risks for plants of frugivory mutualism failures. [source] Diversity and species composition of West African ungulate assemblages: effects of fire, climate and soilGLOBAL ECOLOGY, Issue 6 2008Erik Klop ABSTRACT Aim, Anthropogenic fires are a major component of the ecology of rangelands throughout the world. To assess the effects of these fires on the diversity patterns of herbivores, we related gradients in fire occurrence, climate and soil fertility to patterns in alpha and beta diversity of African ungulates. Location, West Africa. Methods, We used a survey-based approach for ungulates in 37 protected areas in desert, savanna and rain forest habitats throughout West Africa, combined with satellite images of fire occurrence and digital maps of actual evapotranspiration and soil fertility. Alpha diversity was related to the environmental variables using conventional and spatial regression models. We investigated beta diversity using partial Mantel tests and ordination techniques, and by partitioning the variance in assemblage composition into environmental and spatial components. Results, The species richness of grazers showed a quadratic relationship with actual evapotranspiration, whereas that of browsers and frugivores showed a linear relationship. However, in the multiple regression models fire occurrence was the only variable that significantly correlated with the species richness of grazers. Soil fertility was weakly related to overall beta diversity and the species richness of browsers, but was non-significant in the multiple regression models. Fire occurrence was the most important variable explaining species composition of the overall species set and of grazers, whereas the assemblage composition of browsers and frugivores was explained mostly by actual evapotranspiration. Main conclusions, In contrast to previous studies, our analyses show that moisture and nutrients alone fail to adequately predict the diversity patterns of grazing ungulates. Rather, the species richness and assemblage composition of grazers are largely governed by anthropogenic fires that modify the quality and structure of the grass sward. Diversity patterns of browsers and frugivores are markedly different from grazers and depend mainly on the availability of moisture, which is positively correlated with the availability of foliage and fruits. Our study highlights the importance of incorporating major human-induced disturbances or habitat alterations into analyses of diversity patterns. [source] Barn Swallows Hirundo rustica disperse seeds of Rooikrans Acacia cyclops, an invasive alien plant in the Fynbos BiomeIBIS, Issue 3 2007LES G. UNDERHILL Rooikrans Acacia cyclops is an invasive plant species in the coastal region of South Africa, especially the Fynbos Biome. It is endemic to southwestern Australia. Seeds are bird-dispersed, mostly by frugivores and granivores. We report that at one locality in South Africa, Barn Swallows Hirundo rustica, normally regarded as obligate foragers of aerial arthropods, also consumed the seeds and associated arils of Rooikrans shrubs and trees. The seeds were voided and the arils digested. Three thousand Barn Swallows in the region where this was observed conceivably consumed and voided two million Rooikrans seeds during the 5-month non-breeding period. Barn Swallows are therefore dispersers of Rooikrans seeds. Many of the bird species known to consume Rooikrans seeds are territorial, so that seeds are not dispersed far beyond existing acacia stands. Barn Swallows cover large distances between feeding areas and roosts, and could therefore disperse seeds far from existing stands. This development adds urgency to the need to eradicate Rooikrans from the Fynbos Biome. [source] Avian distribution in treefall gaps and understorey of terra firme forest in the lowland AmazonIBIS, Issue 1 2005JOSEPH M. WUNDERLE JR We compared the bird distributions in the understorey of treefall gaps and sites with intact canopy in Amazonian terra firme forest in Brazil. We compiled 2216 mist-net captures (116 species) in 32 gap and 32 forest sites over 22.3 months. Gap habitats differed from forest habitats in having higher capture rates, total captures, species richness and diversity. Seventeen species showed a significantly different distribution of captures between the two habitats (13 higher in gap and four higher in forest). Gap habitats had higher capture rates for nectarivores, frugivores and insectivores. Among insectivores, capture rates for solitary insectivores and army ant followers did not differ between the two habitats. In contrast, capture rates were higher in gaps for members of mixed-species insectivore flocks and mixed-species insectivore,frugivore flocks. Insectivores, especially members of mixed-species flocks, were the predominant species in gap habitats, where frugivores and nectarivores were relatively uncommon. Although few canopy species were captured in gap or forest habitats, visitors from forest mid-storey constituted 42% of the gap specialist species (0% forest) and 46% of rare gap species (38% forest). Insectivore, and total, captures increased over time, but did so more rapidly in gap than in forest habitats, possibly as a response to gap succession. However, an influx of birds displaced by nearby timber harvest also may have caused these increases. Avian gap-use in Amazonian terra firme forests differs from gap-use elsewhere, partly because of differences in forest characteristics such as stature and soil fertility, indicating that the avian response to gaps is context dependent. [source] Ecological biogeography of North American mammals: species density and ecological structure in relation to environmental gradientsJOURNAL OF BIOGEOGRAPHY, Issue 6 2000Catherine Badgley Abstract Aim, To evaluate the relationship of climate and physiography to species density and ecological diversity of North American mammals. Location, North America, including Mexico and Central America. Methods, Species density, size structure and trophic structure of mammalian faunas and nine environmental variables were documented for quadrats covering the entire continent. Spatial autocorrelation of species density and the environmental variables illustrated differences in their spatial structure at the continental scale. We used principal component analysis to reduce the dimensionality of the climatic variables, linear multiple regression to determine which environmental variables best predict species density for the continent and several regions of the continent, and canonical ordination to evaluate how well the environmental variables predict ecological structure of mammalian faunas over North America. Results, In the best regression model, five environmental variables, representing seasonal extremes of temperature, annual energy and moisture, and elevation, predicted 88% of the variation in species density for the whole continent. Among different regions of North America, the environmental variables that predicted species density vary. Changes in the size and trophic structure of mammalian faunas accompany changes in species density. Redundancy analysis demonstrated that environmental variables representing winter temperature, frostfree period, potential and actual evapotranspiration, and elevation account for 77% of the variation in ecological structure. Main conclusions, The latitudinal gradient in mammalian species density is strong, but most of it is explained by variation in the environmental variables. Each ecological category peaks in species richness under particular environmental conditions. The changes of greatest magnitude involve the smallest size categories (< 10 g, 11,100 g), aerial insectivores and frugivores. Species in these categories, mostly bats, increase along a gradient of decreasing winter temperature and increasing annual moisture and frostfree period, trends correlated with latitude. At the opposite end of this gradient, species in the largest size category (101,1000 kg) increase in frequency. Species in size categories 3 (101,1000 g), 5 (11,100 kg) and 6 (101,1000 kg), herbivores, and granivores increase along a longitudinal gradient of increasing annual potential evapotranspiration and elevation. Much of the spatial pattern is consistent with ecological sorting of species ranges along environmental gradients, but differential rates of speciation and extinction also may have shaped the ecological diversity of extant North American mammals. [source] Fruit and fibre: the nutritional value of figs for a small tropical ruminant, the blue duiker (Cephalophus monticola)AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009Erin L. Kendrick Abstract Tropical forests throughout the world are home to a guild of small ruminants that consume fruit as a substantial portion of their diet. Because the rumen is relatively inefficient at digesting nonstructural carbohydrates and only slowly digests cellulose, the feeding adaptations of frugivorous ruminants are enigmatic. We examined the nutritional value of wild figs to blue duikers, one of the smallest and most frugivorous ruminants, through chemical analyses and a series of digestion trials with six species of wild African figs. These figs were high in fat, protein, cell wall, lignin and Ca : P ratios, low in sugar and starch, and high in unextractable, fibre-bound tannins when compared with many other fruits. The fibre-bound tannins and protein caused protein digestibility and nitrogen balance to be consistently low or negative. The high fibre content of the figs allowed duikers to only digest 30,60% of energy contained in the figs. However, duikers were able to consume enough digestible energy to maintain body mass during 4-day trials. Therefore, a ruminant digestive system is beneficial to mammals eating high fibre, high-tannin tropical fruit like figs, especially if the mammal is small enough to harvest a sufficient amount to meet its daily energy requirements and has adaptations for reducing the effects of tannins on protein digestibility. Résumé Les forêts tropicales du monde entier abritent toute une faune de petits ruminants dont les fruits constituent une part non négligeable de l'alimentation. Comme le rumen est relativement peu efficace pour digérer les hydrates de carbone non structuraux et ne digère que lentement la cellulose, les adaptations alimentaires des ruminants frugivores sont encore énigmatiques. Nous avons examiné la valeur nutritionnelle des figues sauvages pour le céphalophe bleu, un des ruminants les plus petits et parmi les plus frugivores, au moyen d'analyses chimiques et d'une série d'essais de digestion avec six espèces de figues sauvages africaines. Ces figues étaient riches en graisses, en protéines, en parois cellulaires, en lignine, et leur rapport Ca/P était élevé; elles avaient un contenu faible en sucre et en amidon, et beaucoup de tanins impossibles à extraire, liés aux fibres, comparés à de nombreux autres fruits. Les tanins liés aux fibres et les protéines faisaient que la digestibilité des protéines et l'équilibre azotéétaient en permanence faibles ou négatifs. Le contenu en fibres élevé des figues ne permettait aux céphalophes de digérer que 30 à 60% de l'énergie contenue dans les figues. Cependant, pendant les quatre jours du test, les céphalophes ont pu consommer suffisamment d'énergie digestible pour conserver leur masse corporelle. C'est pourquoi le système digestif des ruminants est bénéfique pour les mammifères qui consomment des fruits tropicaux riches en fibres et en tanins, comme les figues, spécialement si le mammifère est assez petit pour pouvoir en trouver une quantité suffisante pour répondre à ses besoins quotidiens en énergie, et qu'il possède des adaptations qui lui permettent de réduire les effets des tanins sur la digestibilité des protéines. [source] Connecting behaviour and performance: the evolution of biting behaviour and bite performance in batsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 11 2009S. E. SANTANA Abstract Variation in behaviour, performance and ecology are traditionally associated with variation in morphology. A neglected part of this ecomorphological paradigm is the interaction between behaviour and performance, the ability to carry out tasks that impact fitness. Here we investigate the relationship between biting behaviour and performance (bite force) among 20 species of ecologically diverse bats. We studied the patterns of evolution of plasticity in biting behaviour and bite force, and reconstructed ancestral states for behaviour and its plasticity. Both behavioural and performance plasticity exhibited accelerating evolution over time, and periods of rapid evolution coincided with major dietary shifts from insect-feeding to plant-feeding. We found a significant, positive correlation between behavioural plasticity and bite force. Bats modulated their performance by changing their biting behaviour to maximize bite force when feeding on hard foods. The ancestor of phyllostomids was likely a generalist characterized by high behavioural plasticity, a condition that also evolved in specialized frugivores and potentially contributed to their diversification. [source] Destination-based seed dispersal homogenizes genetic structure of a tropical palmMOLECULAR ECOLOGY, Issue 8 2010JORDAN KARUBIAN Abstract As the dominant seed dispersal agents in many ecosystems, frugivorous animals profoundly impact gene movement and fine-scale genetic structure of plants. Most frugivores engage in some form of destination-based dispersal, in that they move seeds towards specific destinations, resulting in clumped distributions of seeds away from the source tree. Molecular analyses of dispersed seeds and seedlings suggest that destination-based dispersal may often yield clusters of maternal genotypes and lead to pronounced local genetic structure. The long-wattled umbrellabird Cephalopterus penduliger is a frugivorous bird whose lek mating system creates a species-specific pattern of seed dispersal that can potentially be distinguished from background dispersal processes. We used this system to test how destination-based dispersal by umbrellabirds into the lek affects gene movement and genetic structure of one of their preferred food sources Oenocarpus bataua, a canopy palm tree. Relative to background dispersal processes, umbrellabird mating behaviour yielded more diverse seed pools in leks that included on average five times more seed sources and a higher incidence of long-distance dispersal events. This resulted in markedly lower fine-scale spatial genetic structure among established seedlings in leks than background areas. These species-specific impacts of destination-based dispersal illustrate how detailed knowledge of disperser behaviour can elucidate the mechanistic link driving observed patterns of seed movement and genetic structure. [source] Fruits, frugivores and the evolutionary arms raceNEW PHYTOLOGIST, Issue 2 2002Joshua J. Tewksbury No abstract is available for this article. [source] Phenology of neotropical pepper plants (Piperaceae) and their association with their main dispersers, two short-tailed fruit bats, Carollia perspicillata and C. castanea (Phyllostomidae)OIKOS, Issue 2 2004Wibke Thies To relate differences in phenological strategies of a group of closely related plants to biotic (pollinators, dispersers) and abiotic (water, light) factors, we studied leafing, flowering, and fruiting phenology of 12 species of Piper (Piperaceae) in a neotropical lowland forest in Panama for 28 months. We asked how Piper may partition time and vertebrate frugivores to minimize possible competition for dispersal agents. Based on habitat preferences and physiological characteristics we discriminate between forest Piper species (eight species) and gap Piper species (four species). Forest Piper species flowered synchronously mostly at the end of the dry season. Gap Piper species had broader or multiple flowering peaks distributed throughout the year with a trend towards the wet season. Both groups of Piper species showed continuous fruit production. Fruiting peaks of forest Piper species were short and staggered. Gap Piper species had extended fruiting seasons with multiple or broad peaks. Both groups of Piper species also differed in their time of ripening and disperser spectrum. Forest Piper species ripened in late afternoon and had a narrow spectrum consisting mainly of two species of frugivorous bats: Carollia perspicillata and C. castanea (Phyllostomidae). Fruits of gap Piper species, in contrast, ripened early in the morning and were eaten by a broader range of diurnal and nocturnal visitors, including bats, birds, and ants. We conclude that the differences in flowering phenology of forest and gap Piper species are primarily caused by abiotic factors, particularly the availability of water and light, whereas differences in fruiting patterns are mostly influenced by biotic factors. The staggered fruiting pattern of forest Piper species may reflect competition for a limited spectrum of dispersers. The long and overlapping fruiting periods of gap Piper species are associated with a larger spectrum of dispersers and may be a strategy to overcome the difficulty of seed dispersal into spatially unpredictable germination sites with suitable light conditions. [source] Correlated evolution of fruit and leaf size in bird-dispersed plants: species-level variance in fruit traits explained a bit further?OIKOS, Issue 3 2002Carlos M. Herrera The astounding morphological diversity exhibited by the fruits of vertebrate-dispersed plants has been traditionally interpreted as the adaptive outcome of divergent selective pressures exerted on plants by the broad array of frugivorous animals involved in seed dispersal. Although the selective capacity of frugivores provides support to this interpretation, recent studies have challenged it by documenting a strong phylogenetic component associated to interspecific variation in most fruit characteristics. Size-related fruit traits provide a conspicuous exception to this pattern, because they exhibit considerable variation at the between-species level which is largely independent of phylogeny and is correlated with consumption by differently-sized dispersal agents. Substantial species-level variance in size-related traits may reflect genuine disperser-driven diversification, but may also be partly influenced by correlated evolution of fruit size with the size of other plant structures. This latter possibility is tested here for bird-dispersed plants of the Iberian Peninsula using phylogenetically independent contrasts. Results demonstrate the existence of correlated evolution of fruit and leaf size at the species level. As all the plant taxa considered have their fruits eaten, and seeds dispersed, by the same relatively reduced set of frugivorous bird species, results suggest that a significant fraction of the variation in fruit size represented in the species sample may be explained as an indirect consequence of variation in leaf size, rather than being associated with adaptive divergence related to seed dispersal agents. [source] Effects of site and fruit size on the composition of avian frugivore assemblages in a fragmented Afrotropical forestOIKOS, Issue 2 2002M. Githiru Factors influencing the interaction between fruiting trees and their frugivorous seed dispersers in fragmented Afrotropical landscapes are poorly known. With the use of Mantel statistics we analysed assemblages of frugivorous birds on 58 individual trees belonging to 11 species growing in seven Kenyan cloud forest fragments. Overall, frugivores showed little specialization on particular trees. Fruit size explained a substantial amount of the variation in frugivore assemblages among different tree species at the same site. In addition, frugivore assemblages on conspecific trees were significantly more similar when the trees occurred at the same site. This location effect was attributable to the different sites and forest fragments (of different sizes and disturbance levels) varying in the densities and composition of their avian frugivores, vegetation composition and tree fruiting phenologies. It was consolidated further by the low mobility of most of these avian frugivores, particularly their reluctance to cross between forest fragments. Habitat disturbance and fragmentation may therefore have affected fruit selection, with implications for both seed dispersal and regeneration. [source] Density compensation in New World bat communitiesOIKOS, Issue 2 2000Richard D. Stevens Understanding the role of competitive interactions in shaping the structure of communities has been one the most unrelenting challenges to ecology. Traditionally, competitive interactions were assumed to be the most important agent of deterministic structure, with overdispersed morphological patterns based on body size and trophic status as their hallmark. However, models of community organization based solely on morphology have yielded only equivocal results for many taxa. Fortunately, morphological patterns may not be the only indications of competitively induced deterministic structure. Herein, we explore the degree to which the structure of five feeding guilds (aerial insectivores, frugivores, gleaning animalivores, molossid insectivores, and nectarivores) from 15 New World bat communities reflects density compensation. Nonrandom associations between abundance and morphological distance were detected in five communities, in three feeding guilds, and with respect to four competitive scenarios. Nonetheless, patterns consistent with the hypothesis of density compensation were neither pervasive nor consistent in New World bat communities. Competitively induced community structure may exist under only narrow temporal and environmental conditions, and may not be characteristic of organization in most situations. [source] Maximum ingested food size in captive strepsirrhine primates: Scaling and the effects of dietAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2010Jonathan M.G. Perry Abstract Little is known about ingested food size (Vb) in primates, even though this variable has potentially important effects on food intake and processing. This study provides the first data on Vb in strepsirrhine primates using a captive sample of 17 species. These data can be used for generating and testing models of feeding energetics. Strepsirrhines are of interest because they are hypometabolic and chewing rate and daily feeding time do not show a significant scaling relationship with body size. Using melon, carrot, and sweet potato we found that maximum Vb scales isometrically with body mass and mandible length. Low dietary quality in larger strepsirrhines might explain why Vb increases with body size at a greater rate than does resting metabolic rate. Relative to body size, Vb is large in frugivores but small in folivores; furthermore scaling slopes are higher in frugivores than in folivores. A gross estimate of dietary quality explains much of the variation in Vb that is not explained by body size. Gape adaptations might favor habitually large bites for frugivores and small ones for folivores. More data are required for several feeding variables and for wild populations. Am J Phys Anthropol 142:625,635, 2010. © 2010 Wiley-Liss, Inc. [source] Primate communities: Past, present, and possible futureAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S39 2004Kaye E. Reed Abstract An understanding of the fundamental causes of the structure of primate communities is important for studies of primate evolutionary history, primate behavioral ecology, and development of conservation strategies. Research into these structuring factors has benefited from new perspectives such as consideration of primate phylogenetic history, metacommunities, and interactions with predators and nonprimate competitors. This review presents the underlying factors of primate community structure within the biogeographic regions of Madagascar, the Neotropics, Africa, and Asia. One of the major differences among these locations likely resulted from the initial primate taxa that colonized each region (a single colonization event in the case of Madagascar and South America, and multiple radiations of higher-level taxa in Africa and Asia). As most primates live in forests, the differences among the forests in these locations, caused by various climatic influences, further influenced speciation and the development of primate communities. Within these habitats, species interactions with different groups of organisms were also instrumental in developing community dynamics. Through an investigation of these fundamental factors, we identify some of the most important effects on primate communities in each region. These findings suggest that low primate richness in Asia may be caused by either the abundance of dipterocarp trees or high levels of monsoon rains. High numbers of frugivores and a lack of folivores in neotropical communities may be associated with competiton with sloths that were already present at the time of initial radiation. Climatic patterns which affect forest structure and productivity in Madagascar may be responsible for high numbers of folivorous lemurs. The identification of these factors are important for the conservation of existing primate communities, and indicate directions for future studies. Yrbk Phys Anthropol 47:2,39, 2004. © 2004 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||