Comparative phylogeography of a sibling pair of rainforest Drosophila species (Drosophila serrata and D. birchii)

Abstract

Drosophila serrata and D. birchii are presumed sibling species; the former is a widespread generalist and the latter is restricted to rainforests. Comparison of the mtDNA sequence phylogeographies revealed two highly divergent, geographically distinct lineages of D. serrata that are as distinct from each other as either is from D. birchii. However, diversity in D. birchii is low and unstructured. The low diversity in D. birchii corresponds with a late-Pleistocene-Holocene contraction of lowland rainforests. We suggest that future studies of speciation and adaptation should compare the two lineages of D. serrata to each other as well as to D. birchii.