Phylogenetic relationships of the Australo-Papuan Liasis pythons (Reptilia : Macrostomata), based on mitochondrial DNA

Abstract

The genus Liasis comprises two groups of pythons, the olive python, Liasis olivaceus, and the water pythons L. fuscus and L. mackloti. We used partial mitochondrial control region DNA sequences to examine (a) the phylogeography of water pythons from five Indonesian Lesser Sunda islands, New Guinea, and northern Australia, (b) the relationships of the two subspecies of olive pythons, and (c) the relationship of the Papuan python, Apodora papuana, with the species of Liasis. Maximum likelihood, parsimony and distance analyses showed that A. papuana is the sister lineage to all Liasis and that Liasis fuscus/L. mackloti and L. olivaceus are separate lineages. There is also support for the reciprocal monophyly of the two olive python subspecies, L. olivaceus barroni and L. o. olivaceus, and for distinction of island populations described previously as L. mackloti dunni from Wetar and L. mackloti savuensis from Sawu. These two island populations are as equally distinct as the populations from the island cluster of Babar/Semau/Timor. There is strong support for the recognition of two lineages ('eastern' and 'western') of water pythons in Australia. We propose that the drier interior of the Plio-Pleistocene land bridge between Australia and New Guinea acted as a barrier to gene flow, influencing the genetic divergence between the 'eastern' and 'western' lineages of the semi-aquatic water pythons.