Testing landscape effects on the evolution of island arthropod assemblages

Abstract

Geographic isolation is a recognised driver of speciation within oceanic island archipelagos, with the chance colonisation and establishment of species from one island to another being a cornerstone for the origin of new evolutionary lineages. The importance of geographic isolation within islands is less clear, as current distributions of closely related species may not be reflective of the geography of their shared ancestors. It may also be that physical geographic distance has been less important than ecological distance for the initiation of the speciation process within islands. We are addressing this information gap by testing for geographical and ecological isolation effects through the sampling of whole arthropod communities within insular forest biomes. We combine standardised ecological sampling with DNA sequencing and apply both traditional (FST-based) and novel (Bayesian MCMC) analyses of molecular data. In this presentation I will outline our study system and our methodological approach for the investigation of geographic effects on genetic differentiation among the Coleoptera fauna sampled within a topographically complex insular forest biome. I will illustrate our approach with some preliminary results and discuss their significance.