Biogeographic processes determining the distributions of European bats across spatial scales: the role of biotic interactions and habitat preferences

Abstract

A better comprehension of how natural systems will respond to global environmental changes requires a deeper understanding of the processes that drive diversity. In this thesis I show how environmental filtering and biotic interactions operate across spatial scales contributing to shaping biogeographic patterns. Among the different environmental filtering factors that drive species’ geographical ranges, habitat structure is thought to operate generally at more local scales than climatic factors. I show, however, that forest characteristics can be a primary factor driving the regional distribution of forest-specialist bats in a Mediterranean system, which has direct consequences for their vulnerability to climate change. The strength of this dependence on forests is driven by species’ roosting ecology, being higher in species that roost in trees. Alongside environmental filtering, biotic interactions can impact species distributions by preventing functionally similar species from coexisting. I show how local-scale trophic shift can facilitate coexistence between the morphologically almost identical forest bats Myotis escalerai and Myotis crypticus. Increasing evidence supports the effect of biotic interactions on broader scale biogeographic patterns. I develop a measure that uses outputs of Species Distribution Models to detect the expected broad-scale patterns of geographic avoidance between pairs of species if competition contributes to shaping their ranges. When applying it to different sets of bats with high potential for competition, the measure showed higher values than random for two pairs of species that are ecologically very similar and have no known local-scale coexistence mechanisms. This suggests that local-scale coexistence mechanisms are a key process preventing biotic interactions from scaling up and having broader-scale consequences. Overall, this thesis highlights the importance of integrating new molecular techniques, functional analyses and a careful consideration of spatial scale for disentangling ecological and biogeographic processes.

More information

Identifiers

ORCID for Orly Razgour: orcid.org/0000-0003-3186-0313

Catalogue record

Export record