Consecuencias evolutivas y ecológicas de las interacciones murciélago-planta en el caribe insular

Resumo

Ecological interactions are among the most important biotic factors influencing the processes of speciation and extinction. Research on the role of mutualistic interactions in diversification of insular lineages is very much needed because the evolution of mutualisms as mechanism of adaptive radiation has been poorly explored. This dissertation aimed to analyse the relationship between diet diversification and evolution of the New World family of leaf-nosed bats (Phyllostomidae), with special emphasis in specialisation for frugivory and for nectarivory. This family has undergone an ecological diversification throughout the Neotropics without parallel in mammals. Particularly in the West Indies, phyllostomids have diversified in extremely specialised and generalist endemic genera. Furthermore, evidence suggests that dietary specialisation even shapes the temporal activity patterns of these mammals. To meet the aim we estimated time-calibrated molecular phylogenies of phyllostomids and related families. We also performed ancestral state reconstructions of discrete characters, conducted analyses of diversification, and tested evolutionary correlation of different traits. Our results strongly support the parallel evolution of frugivory in at least three lineages and of nectarivory in at least two lineages of the family during the Miocene. This clarifies a 10-year debate about the origin and evolution of nectarivory in New World bats. However, we found no evidence for a phytophagous (or at least, omnivorous) ancestor of Phyllostomidae. In exploring the relation of ecological interactions and diversification of New World Noctilionoidea, we found that diversification rate of mutualistic clades has been higher than that of antagonistic. Geographical range and number of ecoregions were positively associated with species richness and diversification rate in continental and insular lineages. This supports the hypothesis that occupation of new habitats is a source of ecological opportunity that led to a significant increase in taxonomic diversification rates. Specialisation for frugivory was positively related to diversification in mainland, but was negatively related in the Antilles. Our results showed that feeding behaviour, including food handling, has a variable effect on brain volume after accounting for body mass and controlling for the strength of the phylogenetic signal. We also showed that comparative analysis may lead to misleading conclusions if the phylogenetic signal is not quantified appropriately. Finally, we developed an index of priority setting of site conservation based on network theory and evolutionary distinctiveness. We exemplified the application of the index with assemblages of cave-dwelling bats of the Greater Antilles. Including evolutionary distinctiveness in the index helped to establish priorities among the assemblages that play a similar role in the network of sites. The family Phyllostomidae still has much to offer as a study model. Embedding comparative phylogenetic methods into ecological research offer a great opportunity for an integrative approach to the study of adaptive radiations.