Phylogenetic relationships of the heath dragons (Rankinia adelaidensis and R. parviceps) from the south-western Australian biodiversity hotspot

Abstract

Although the south-western Australian region is recognised as a global biodiversity hotspot, there are still significant gaps in our understanding of the biodiversity of this region. We present a phylogenetic study of the heath dragons (Rankinia adelaidensis and R. parviceps) from this region, incorporating a 1612-bp section of mtDNA and two nuclear introns, Gapdh (~244 bp) and Enol (~330 bp). In addition, we present a generic-level analysis of three gene regions (mtDNA, Gapdh, BDNF), which provides clear evidence that Rankinia adelaidensis and R. parviceps are not closely related to Rankinia diemensis from eastern Australia. Instead, the heath dragons are strongly supported as forming a clade with the genus Ctenophorus. In addition, we find that there are significant levels of haplotype divergence between currently recognised subspecies of the heath dragons (R. a. adelaidensis, R. a. chapmani, R. p. parviceps, R. p. butleri). We suggest that the genetic divergences between subspecies result from geographic isolation in allopatry owing to habitat preferences, followed by drift and/or selection. On the basis of these deep divergences and consistent morphological differences between subspecies, we recommend elevating all taxa to full species, and provide a taxonomic revision of the genera Rankinia and Ctenophorus.