Two complete mitochondrial genomes of Crocodylus and implications for crocodilians phylogeny

Abstract

The complete mitochondrial (mt) genomes of two crocodilians: Crocodylus palustris and Crocodylus mindorensis, were sequenced in order to examine their gene and genome features. Additionally, we intended to increase the amount of molecular data suitable for phylogenetic analysis. Their gene orders conform to other crocodilians that have been sequenced, except the arrangement of two tRNA genes differ from other vertebrates, showing that the gene order of crocodilians is remarkably conserved. Phylogenetic analyses (maximum likelihood, Bayesian inference) based on the mt protein-coding genes at the nucleotide level were performed among crocodilians for which complete mt genomes were available. The results suggest that the gharial (Gavialis gangeticus) joins the false gharial (Tomistoma schlegelii) on a common branch, that constitutes a sister group to traditional Crocodylidae. In this report, Mecistops cataphractus is evidently most closely related to Osteolaemus tetraspis. They are isolated as sister taxon from the main clades in Crocodylus. Regarding Paleosuchus, it appears as sister group to Caiman within the Alligatoridae. In particular, relationships among species of Crocodylus (true crocodiles) are discussed. © 2010 Koninklijke Brill NV, Leiden.