The Thevenard Island mouse: historic and conservation implications from mitochondrial DNA sequence-variation

Abstract

The level of mitochondrial differentiation between Thevenard Island and mainland populations of the short-tailed mice Leggadina lakedownensis was determined using DNA sequencing of the Control Region. Using temperature gradient gel electrophoresis, outgroup heteroduplex analysis detected eight haplotypes. These were sequenced for 362 basepairs. Our results show that the Thevenard Island Short-tailed Mouse is indeed L. lakedownensis, and is most closely related to L. lakedownensis in the Pilbara in Western Australia. Together, Thevenard Island and adjacent mainland populations are sufficiently divergent from those in northern Australia as to be recognized as two clearly distinct mitochondrial DNA lineages. Conservation and taxonomic implications arising from a phylogeny of haplotypes suggest that two Management Units exist within L. lakedownensis ? a northern unit that includes individuals from the Kimberley (Western Australia) to Kakadu National Park (Northern Territory), and a western unit comprising individuals from Thevenard Island and the Pilbara (Western Australia). These conservation units should be managed as separate subspecies of L. lakedownensis, and a high conservation priority should be given to the Thevenard Island population because it provides an important refugium for L. lakedownensis not just in the Pilbara, but in Australia.