Evolutionary diversification of the lizard genus Bassiana (Scincidae) across Southern Australia.
BACKGROUND
Relatively recent (Plio-Pleistocene) climatic variations had strong impacts on the fauna and flora of temperate-zone North America and Europe; genetic analyses suggest that many lineages were restricted to unglaciated refuges during this time, and have expanded their ranges since then. Temperate-zone Australia experienced less severe glaciation, suggesting that patterns of genetic structure among species may reflect older (aridity-driven) divergence events rather than Plio-Pleistocene (thermally-mediated) divergences. The lizard genus Bassiana (Squamata, Scincidae) contains three species that occur across a wide area of southern Australia (including Tasmania), rendering them ideally-suited to studies on the impact of past climatic fluctuations.


RESULTS
We performed molecular phylogenetic and dating analyses using two partial mitochondrial genes (ND2 and ND4) of 97 samples of Bassiana spp. Our results reveal a pattern of diversification beginning in the Middle Miocene, with intraspecific diversification arising from 5.7 to 1.7 million years ago in the Upper Miocene-Lower Pleistocene.


CONCLUSIONS
In contrast to the temperate-zone Northern Hemisphere biota, patterns of evolutionary diversification within southern Australian taxa appear to reflect geologically ancient events, mostly relating to east-west discontinuities imposed by aridity rather than (as is the case in Europe and North America) relatively recent recolonisation of northern regions from unglaciated refugia to the south.
Dubey
Sylvain
S
School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia. sylvain.dubey@bio.usyd.edu.au
Shine
Richard
R
D000818:Animals; D001315:Australia; D044822:Biodiversity; D019143:Evolution, Molecular; D008116:Lizards / Q000145:classification* / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny
D024101:Mitochondrial Proteins