Biogeography of Southern Hemisphere arthropods: a comparative molecular phylogenetic appraoch

Our understanding of the current distributions of the southern hemisphere biota remains controversial, despite recent studies finding that both vicariance and long-distance dispersal have each played major roles. The interplay between spatial isolation and gene flow is one that can be observed in modern-day species, but there is still a broad perception that much of the austral biota has an “ancient gondwanan” distribution.

Unlike the apparent situation in plants, which show a strong pattern of relatively frequent past long-distance dispersal, published animal studies (relying heavily on insect phylogenies inferred from morphological data, and not considering the timing of events) have found that animals better fit a pattern of Gondwana vicariance. Here we analyse newly available DNA sequence datasets for about 20 arthropod groups and explicitly consider the timing of inferred divergence events. Our results suggest that arthropod distributions are more similar to that of plants than to the more closely related vertebrates.