Signatures of speciation: From theoretical mechanisms to observable patterns
Species formation has traditionally been thought of as requiring genetic divergence between geographically segregated populations over geological timescales. More recent research has highlighted that, in contrast, species formation may occur frequently, and much faster, through local competition. While this alternative speciation mechanism, called adaptive speciation, is theoretically plausible, empirical evidence for its prevalence in nature is yet scant. This is mostly because the resulting biogeographic patterns are very similar to those resulting after species that initially diverged in geographic isolation again come into contact at a later stage.
The aim of this project is to identify post-speciation patterns—in terms of ecological, spatial, and reproductive differentiation among the resultant species—that allow the underlying speciation processes to be inferred, and in particular, a distinction to be made between adaptive speciation caused by local competition and its traditional alternative caused by geographic isolation. Guided by empirical data from a system of Mid-Atlantic island finches, I will investigate such patterns in different settings and evaluate their imprint on emerging patterns of genetic differentiation. By fostering insights into the mechanisms of speciation, the plausibility and prevalence of different such mechanisms, and our ability to infer underlying past processes from observations of present patterns more generally, this project will shed light on conditions promoting the formation of biodiversity.