Evaluating the macro and micro geographic mechanisms that modulate the coexistence between sympatric Sturnira bat species

Abstract

One of the key questions in ecology is to understand the mechanisms that modulate thecoexistence between sympatric species. Climate and habitat perturbation gradients havebeen proposed as moderators of species coexistence. The first is related to availability andthe diversity of food resources. The second is related to change in habitat structure that promoteschanges in plant structure and diversity that impacts the diversity of other organisms.Although there is empirical evidence that supports these mechanisms to explain coexistence,they have not been evaluated quantitatively and on a wide geographic scale. Usingphytophagous bat species of the genus Sturnira we evaluated both mechanisms. These batsare morphologically similar and are key organisms for the seed dispersal of Neotropicalforest plants. Using systematic review protocols, we obtained data of the occurrence andrelative abundance of sympatric Sturnira species of different Neotropical forests. We usedgeneralized linear models to evaluate the predictor power of Holdridge’s life zones andhabitat disturbance type to explain the evenness of sympatric Sturnira species. Life zonesdid not explain the variation in evenness of sympatric species of Sturnira. However, wefound that the type of disturbance and individuals captured explain the variation of evennessin Sturnira species. Grasslands present the higher Sturnira species evenness, whilesites with lower bat captures had higher evenness. These suggest that the reduction of vegetationcomplexity allows the coexistence among these highly related species, via the reductionof their relative abundances.