Genetic variation and bone morphology of newts genus tylototriton in Thailand

Abstract

The genetic variation and bone morphology of the Himalayan newt (Tylototriton verrucosus) in Thailand were examined through field surveys, which were carried out at 14 locations in 7 provinces of Thailand, from December 2001 to September 2006. It was observed that, in Thailand, this species can be divided into two morphotypes based upon the body coloration (orange to yellow and dull colorations), and female sizes (orange to yellow type was noticeably bigger than dull type). The two morphotypes as described also coincided with their current distribution ranges (northern and northeastern mountain ranges). The current local distributions within Thailand of both two types of T. verrucosus were evaluated with new localities discovered and are reported. Other information including habitat, reproduction and external morphology were also recorded. Among 7 populations, genetic variation of 21 individuals was examined using DNA sequence analysis of two mitochondrial DNA gene fragments: 16S ribosomal RNA (498-500 base pairs) and D-loop (729-730 base pairs). Phylogenetic relationships were established using distance and maximum likelihood methods. The clear findings revealed the existences of two distinct genetic lineages, which are related to their geographic distributions and color patterns. Osteological investigation of 12 specimens, from 6 populations, revealed obvious differences between northern and northeastern populations of T. verrucosus. These data showed that there are two morphotypes of T. verrucosus in Thailand, based on the distribution patterns, molecular characters, and bone morphology.