28 research outputs found

    Secondary forest regeneration benefits old-growth specialist bats in a fragmented tropical landscape

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    Tropical forest loss and fragmentation are due to increase in coming decades. Understanding how matrix dynamics, especially secondary forest regrowth, can lessen fragmentation impacts is key to understanding species persistence in modified landscapes. Here, we use a whole-ecosystem fragmentation experiment to investigate how bat assemblages are influenced by the regeneration of the secondary forest matrix. We surveyed bats in continuous forest, forest fragments and secondary forest matrix habitats, similar to 15 and similar to 30 years after forest clearance, to investigate temporal changes in the occupancy and abundance of old-growth specialist and habitat generalist species. The regeneration of the second growth matrix had overall positive effects on the occupancy and abundance of specialists across all sampled habitats. Conversely, effects on generalist species were negligible for forest fragments and negative for secondary forest. Our results show that the conservation potential of secondary forests for reverting faunal declines in fragmented tropical landscapes increases with secondary forest age and that old-growth specialists, which are often of most conservation concern, are the greatest beneficiaries of secondary forest maturation. Our findings emphasize that the transposition of patterns of biodiversity persistence in island ecosystems to fragmented terrestrial settings can be hampered by the dynamic nature of human-dominated landscapes.Peer reviewe

    Predicting biodiversity loss in island and countryside ecosystems through the lens of taxonomic and functional biogeography

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    We investigate how variation in patch area and forest cover quantified for three different spatial scales (buffer size of 500, 1500 and 3000 m radius) affects species richness and functional diversity of bat assemblages in two ecosystems differing in fragment–matrix contrast: a landbridge island system in Panama and a countryside ecosystem in the Brazilian Amazon. Bats were sampled on 11 islands and the adjacent mainland in Panama, and in eight forest fragments and nearby continuous forest in Brazil. Species–area relationships (SAR) were assessed based on Chao1 species richness estimates, and functional diversity–area relationships (FAR) were quantified using Chao1 functional diversity estimates measured as the total branch length of a trait dendrogram. FARs were calculated using three trait sets: considering five species functional traits (FARALL), and trait subsets reflecting ‘diet breadth’ (FARDIET) and ‘dispersal ability’ (FARDISPERSAL). We found that in both study systems, FARALL was less sensitive to habitat loss than SAR, in the sense that an equal reduction in habitat loss led to a disproportionately smaller loss of functional diversity compared to species richness. However, the inhospitable and static aquatic matrix in the island ecosystem resulted in more pronounced species loss with increasing loss of habitat compared to the countryside ecosystem. Moreover, while we found a significant FARDISPERSAL for the island ecosystem in relation to forest cover within 500 m landscape buffers, FARDIET and FARDISPERSAL were not significant for the countryside ecosystem. Our findings highlight that species richness and functional diversity in island and countryside ecosystems scale fundamentally differently with habitat loss, and suggest that key bat ecological functions, such as pollination, seed dispersal and arthropod suppression, may be maintained in fragments despite a reduction in species richness. Our study reinforces the importance of increasing habitat availability for decreasing the chances of losing species richness in smaller fragments

    Consequences of a large-scale fragmentation experiment for Neotropical bats : disentangling the relative importance of local and landscape-scale effects

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    Context Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management. Objectives We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient. Methods We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics. Results Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats. Conclusions Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat

    Environmental factors are stronger predictors of primate species’ distributions than basic biological traits

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    Understanding the neutral, biological and environmental processes driving species distributions is valuable in informing conservation efforts because it will help us predict how species will respond to changes in environmental conditions. Environmental processes affect species differently according to their biological traits, which determine how they interact with their environment. Therefore, functional, trait-based modelling approaches are considered important for predicting distributions and species responses to change but even for data-rich primate communities our understanding of the relationships between traits and environmental conditions is limited. Here we use a large-scale, high-resolution dataset of African diurnal primate distributions, biological traits and environmental conditions to investigate the role of biological traits and environmental trait filtering in primate distributions. We collected data from published sources for 354 sites, and 14 genera with 57 species across Sub-Saharan Africa. We then combined a three-table ordination method, RLQ, with the Fourth Corner approach to test relationships between environmental variables and biological traits and used a mapping approach to visually assess patterning in primate genus and species’ distributions. We found no significant relationships between any groups of environmental variables and biological traits, despite a clear role of environmental filtering in driving genus and species’ distributions. The most important environmental driver of species distributions was temperature seasonality, followed by rainfall. We conclude that the relative flexibility of many primate genera means that not any one particular set of traits drives their species-environment associations, despite the clear role of such associations in their distribution patterns

    Forest area predicts all dimensions of small mammal and lizard diversity in Amazonian insular forest fragments

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    Context: Although hydropower development is one of the primary drivers of habitat loss and insular fragmentation, its impacts on species identity and their functional and phylogenetic roles have often been overlooked. Objectives: Here we use an integrative approach, considering taxonomic, functional and phylogenetic dimensions at multiple scales, to understand the processes underlying species (dis)assembly of two taxa exhibiting relatively low dispersal ability: small mammals and lizards. Methods: We surveyed 26 islands within the Balbina Hydroelectric Reservoir, and adjacent continuous forest, in Central Amazonia. Each dimension of diversity was related to spatial and habitat variables. We also examined functional composition using community-weighted mean trait values, and community redundancy using functional uniqueness. β-diversity was partitioned into their richness (βrich) and replacement (βrepl) components. Results: Functional and phylogenetic α-diversities of both taxa mirrored the taxonomic dimension, all of which increased with forest area. Individual small mammal (body mass and matrix tolerance), and lizard traits (body length, heliothermic mode and habitat type) were also predicted by forest area. For both groups, functional uniqueness decreased with forest area, and all dimensions of β-diversity were predominantly partitioned in βrich. Conclusions: The environmental filter created by forest area resulted in the low conservation value associated with small forest islands, only occupied by a small set of species comprised by generalist lizards and matrix-tolerant small mammals. On the other side, large forest sites ensured ecosystem resilience to disturbance. To maintain ecosystem integrity, creating myriad small islands over large expanses of floodwaters should be avoided in future hydropower development

    Reproductive phenologies of phyllostomid bats in the Central Amazon

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    Mammals tend to align their most energetically demanding phenological events with periods of peak resource availability. Their reproductive phenology is influenced by local resource availability, potentially leading to geographical variation in their breeding strategy. Although the Amazon is the world’s epicenter of bat diversity, the reproductive phenology of Amazonian bats remains poorly known. Seasonality induces fluctuations in resource availability and most phyllostomid species, crucial agents of seed dispersal, pollination and arthropod suppression in the Neotropics, have been described to exhibit seasonal bimodal polyestry. However, current understanding of phyllostomid reproductive phenology is impaired by the paucity of comparative examinations of the phenologies of sympatric species, using consistent classification schemes based on the number and timing of annual peaks in pregnancy and lactation. Using a multi-year dataset from Central Amazonia, we examined the reproductive phenology of nine bat species (Artibeus concolor, A. obscurus, A. lituratus, Carollia brevicauda, C. perspicillata, Gardnerycteris crenulatum, Lophostoma silvicolum, Rhinophylla pumilio, and Trachops cirrhosus), as well as two feeding ensembles (i.e., frugivores and gleaning animalivores). Only three of the nine species exhibited a bimodal reproductive phenology. Six species and the frugivore ensemble showed unimodal reproductive phenology, while gleaning animalivores displayed an amodal pregnancy pattern. All species except L. silvicolum had their primary pregnancy peak during the mid-dry season. A reproductive peak during the early wet season, or local variation in the duration of the fruiting season may explain the deviation of our observations from the expected bimodal polyestry

    Trait-mediated filtering predicts phyllostomid bat responses to habitat disturbance in the Orinoco Llanos

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    Which functional traits allow a bat species to survive habitat disturbance? Empirical evidence regarding this question remains limited for many tropical regions despite their importance for conservation. Here, we used body mass, wing morphology, trophic level, and diet to identify which traits make phyllostomid bat species more vulnerable to human impacts in the Colombian Orinoco Llanos. Bats were sampled using mist nets in riparian forests, unflooded forests, flooded savannahs, and conventional rice crops on traditional farmlands with high-intensity agriculture and in private reserves with greater ecosystem protection. We tested the associations between species traits and landscape-structure variables (habitat cover and type, number of habitat patches, shortest distance to water) using RLQ and fourth-corner analyses, accounting for both spatial and phylogenetic autocorrela-tion. Trophic level and diet were the most important traits linked to disturbance sensitivity. Our results indicated that rice crop cover, savannah patches, and altered unflooded forest act as a filter, benefiting disturbance-adapted frugivorous genera in farmlands (e.g., Ar-tibeus spp., Carollia spp., Platyrrhinus spp., Uroderma spp.). Conversely, animalivorous species were strongly associated with savannah cover and riparian forests within reserves (e.g., Lampronycteris brachyotis, Lophostoma brasiliense, Micronycteris minuta, Tra-chops cirrhosus). Encouraging the creation of more wildlife-friendly landscapes through payments for ecosystem services across the Colombian Llanos will ensure the long-term persistence of disturbance-sensitive species and sustain a complete set of ecological functions and ecosystem services that these bats provide
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