A molecular phylogenetic perspective on the evolutionary radiation of the salamander family salamandridae

Phylogenetic relationships were examined within the salamander family Salamandridae using 18 species representing 14 salamandrid genera and six outgroup taxa from the families Ambystomatidae, Dicamptodontidae, Plethodontidae, and Proteidae. Mitochondrial DNA sequences encoding the 12S and 16S ribosomal RNA and the intervening valine transfer RNA provided 431 phylogenetically informative nucleotide sequence positions from a multiple alignment of approximately 1, 000 bases per species. This variation was analyzed in conjunction with 44 previously reported morphological characters representing primarily hyobranchial myology and osteology, cranial osteology, and reproductive biology. The molecular and morphological character sets were highly congruent, with only 2.8% of the total character incongruence attributable to conflict between them. Parsimony analysis of the combined molecular and morphological data produced a single most-parsimonious tree whose topology was identical to that of the mostparsimonious tree derived from the molecular data alone. This tree suggests that the salamanders (Chioglossa, Mertensiella, and Salamandra) form a monophyletic sister group to the newts (all remaining salamandrid genera). Within the newts, the first phylogenetic split separates Salamandrina from the remaining genera, within which Pleurodeles and Tylototriton form a monophyletic sister group to the remaining taxa. The genus Triturus appears not to be monophyletic. Using a phylogenetic reconstruction of character changes, we tested hypotheses of adaptation in the evolution of aquatic suction feeding and terrestrial feeding featuring tongue protrusion. Phylogenetic trends in the evolution of salamandrid courtship behavior were also examined.