Abstract
Habitat loss and fragmentation rank high amongst the most pressing threats to biodiversity. Understanding how variation in functional traits is associated with species vulnerability in fragmented landscapes is central to the design of effective conservation strategies. Here, we used a whole-ecosystem ecological experiment in the Central Amazon to investigate which functional traits of aerial-hawking insectivorous bats best predict their sensitivity to forest fragmentation. During 2014, bats were surveyed using passive bat recorders in six continuous forest sites, eight forest fragments, eight fragment edges, and eight forest clearings. The interaction between functional traits, environmental characteristics, and species distribution was investigated using a combination of RLQ and fourth-corner analyses. Our results showed that echolocation call structure, vertical stratification, and wing aspect ratio were the strongest predictors of sensitivity to forest fragmentation. Frequency of maximum energy, body mass, and relative wing loading did not show any correlation with the environmental variables. Bat species with constant-frequency calls were associated with high vegetation density, being more susceptible to forest fragmentation than species with frequency-modulated calls. Vertical stratum preference was also correlated with vegetation structure, indicating that understory species were more sensitive to forest loss than canopy species. Finally, species with high aspect ratio wings were linked to forest edges and clearings. Our findings suggest that species functional traits determine the vulnerability of aerial-hawking insectivorous bats toward fragmentation and, similarly, environmental conditions determine if a species is likely to become locally extinct due to fragmentation. Preserving structurally complex forests will be crucial to ensure the long-term persistence of the most sensitive and vulnerable species of this bat ensemble in fragmented landscapes across the Neotropics.
Highlights
The exponential increase of the human population and growing per capita consumption of resources are causing widespread habitat loss and degradation, which are threatening the survival of numerous species worldwide (Dirzo et al, 2014; Laurance et al, 2014)
In the principal component analysis (PCA) of the R table (Figure 2), sites grouped according to the gradient made up by the different habitat categories, with all forest interior sites well-separated from clearings and fragment edges along the first axis
We found that a combination of species functional traits and environmental characteristics were relevant predictors of the sensitivity of AIB toward fragmentation, a finding that may apply across many human-modified Neotropical landscapes
Summary
The exponential increase of the human population and growing per capita consumption of resources are causing widespread habitat loss and degradation, which are threatening the survival of numerous species worldwide (Dirzo et al, 2014; Laurance et al, 2014). Human-induced habitat modification is creating increasingly fragmented landscapes composed of smaller and isolated primary habitat patches (Haddad et al, 2015; Taubert et al, 2018), usually embedded in a matrix that is often a mosaic of different habitats that affect both species diversity and composition (Ewers and Didham, 2006; Kupfer et al, 2006; Kennedy et al, 2011; Loureiro and Gregorin, 2015). Low matrix permeability negatively affects local biodiversity as it reduces connectivity and increases the effects of isolation of remnant patches (Ricketts, 2001; Estrada-Villegas et al, 2010)
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