A molecular phylogeny of the Australian monitor lizards (Squamata:Varanidae) inferred from mitochondrial DNA sequences

Abstract

To date no complete phylogeny of all of the currently recognised Indo-Australian varanid species and subspecies has been published. This paper presents a comprehensive mitochondrial gene phylogeny of these lizards. A portion of the mitochondrial genome comprising part of the ND4 gene and three adjacent tRNA genes (hereafter referred to as ND4) was analysed alone and, for a subset of the taxa, combined with previously published mitochondrial data. Similar tree topologies were produced by both datasets although combining the data helped resolve some of the unresolved or weakly supported nodes in the ND4 analyses. The monophyly of the Indo-Australian group was strongly supported in all analyses. This group comprised three major lineages: the gouldii group, the Odatria group and the varius group. Mitochondrial ND4 nucleotide sequences were successfully amplified from all of the Indo-Australian monitor species and subspecies currently recognised and, as such, is the first comprehensive phylogenetic study of the Australian monitor lizards published. Analysis of the tempo of diversification and evolution of preferred habitat use identified six episodes of increased net speciation rate, with two closely adjacent episodes showing the highest rates of diversification and correlating with the appearance of all preferred habitat types. The comprehensive molecular phylogenetic framework will also be useful for the identification of varanid species and traded products derived from monitors and, as such, has important applications for wildlife management and conservation.

Molecular evidence for an Asian origin of monitor lizards followed by Tertiary dispersals to Africa and Australasia

“…Within the Indo-Australian group, four major groups are found: the 'varius group' which clusters with the 'gouldii group' and the 'acanthurus group' which clusters with the 'tristis group'. These relationships within Varanus are congruent with studies based on mitochondrial data only [6,[13][14][15][16]. It is interesting to note that independent evidence derived from genital morphological characters supports several molecular nodes both at the interfamilial (Shinisauridae/ Xenosauridae) and intrageneric (Varanus) level [17].…”

A new blue-tailed Monitor lizard (Reptilia, Squamata, Varanus) of the Varanus indicus group from Mussau Island, Papua New Guinea

“…The subgenus is geographically restricted to a large region east of Wallace’s line with the Solomon Islands and parts of Micronesia forming the eastern and northern boundaries (Ziegler et al 2007a, Sweet and Pianka 2007). The systematic arrangement is well-supported by molecular and morphological studies (Ziegler and Böhme 1997, Fitch et al 2006, Vidal et al 2012). Several new monitor lizards of the subgenus Euprepiosaurus have been discovered from islands in the southwest Pacific since the early 1990s.…”

Re-assessment of varanid evolution based on new data from Saniwa ensidens Leidy, 1870 (Squamata, Reptilia)

“…Pianka (1995) recovered a slightly different result, using different techniques. Fitch et al (2006) analyzed relationships among a subset of Varanus, and their results generally agree with those of Ast (2001).…”