Gondwanan relic or recent arrival? The biogeographic origins and systematics of Australian tarantulas
Molecular Phylogenetics and Evolution 204: 108246.
Abstract
The composition of Australia's fauna and flora has been largely assembled by two biogeographic processes, vicariance and long-distance dispersal and establishment. Tarantulas (Araneae, Theraphosidae) are largely pan-tropical but also have a low propensity for dispersal, and are thought to be Gondwanan in origin. However, the Australian tarantulas are unsampled for phylogenomic studies and, as such, their classification and biogeographic origins have been long debated and are unresolved. Here we test if their current, morphology-based classification in Selenocosmiinae is accurate and assess whether Australian tarantulas were present in Australia while it was part of Gondwana. We sample 369 tarantula specimens from across Australia, greatly expanding the geographic sampling of previous studies, to develop the first continent-wide phylogeny of the Australian tarantulas. We generate 20 new transcriptomes for species of Australian tarantulas representing distinct lineages uncovered using mitochondrial sequence data. Through the recovery of ultra-conserved element (UCE) loci from transcriptomes and testing multiple data occupancy matrices, we find that the Australian clade is monophyletic and nested inside the largely Asian Selenocosmiinae. We find the Australian fauna are a relatively young radiation with a crown age of 18.8-8.3 Ma and we therefore reject the hypothesis of a Gondwanan origin for these animals and, instead, infer a recent dispersal from south-east Asia. Our findings refute the monophyly of Selenocosmia and Coremiocnemis as currently recognised, and we remove Selenocosmia stalkeri from synonymy with Selenocosmia stirlingi.