Cytogenetics and molecular data in snakes: a phylogenetic approach.

Snakes are among the most successful groups of reptiles, numbering about 3,000 extant species. In spite of centuries of comparative anatomical and morphological studies, many aspects of snake systematics remain unsolved. To better understand the evolution and diversity of genomic characteristics in Serpentes, we analyzed online sequence data of mitochondrial and nuclear genes, as well as cytogenetic data and reviewed other genomic characteristics such as toxin genes. After the analysis of the whole-genome and chromosomal organization, we find that: (1) cytogenetic comparisons could provide a useful tool to investigate intergeneric and tribal relationships within the extremely diverse neotropical xenodontine snakes; (2) toxin genes could also help to understand snake evolution if special care is taken to choose the sequences because of the difficulty in avoiding paralogs; (3) snake phylogeny based on mitochondrial genome sequences is largely consistent with the relationship obtained using nuclear genes.