Reconstructing the Roots of the Amphibian Tree

Abstract

Amphibian systematics is experiencing an era of change. Integrative taxonomy and increased exploration, especially of tropical regions, have led to an explosion in species numbers, with more than a thousand species discovered and described between 2000 and 2009. Some of these new species were breakthroughs of great biogeographic importance, such as Karsenia koreana, the first Asian plethodontid salamander, or Nasikabatrachus sahyadrensis, a representative of a morphologically unique family of frogs in India. Furthermore, important advances in our knowledge of the deep phylogeny of extant amphibians have been achieved through the analysis of DNA sequences, and molecular clocks are coming to a consensus in dating the major nodes of the amphibian tree--leading to an improved understanding of how vicariance and dispersal shaped the current distribution of amphibians and created opportunities for their radiations. These major breakthroughs are reflected in new proposals for amphibian classification at the genus and family levels, which, although still partly disputed, reflect evolutionary history better than previous schemes.