A molecular timescale for the early evolution of extant Amphibia.

The extant Amphibia (Lissamphibia) are divided in three orders each with a highly distinct body plan: (1) anura (frogs and toads), (2) Caudata (salamanders and newts), and (3) Gymnophiona (caecilians). Currently, a time scale for the early evolution of Amphibia, e.g. the divergence of the three orders, one of the main missing clues for the construction of an evolutionary synthesis for Amphibia. Morphological as well as traditional molecular-phylogenetic techniques lack the accuracy to resolve this questionwith statistical significance and several paleontological, biogeographical and molecular studies have resulted in controversial hypotheses, for which no consensus has been found. Complete resolution of divergences however is possible by screening the genome for Rara genomic changes (RGC's), being macro-mutations in the genome of a certain clade. Reliable estimations of divergence dates, even in the absence of a molecular clock, are possible by analysis of large datasets by means of a recently developped Bayesian approach.
In this project, we try to: (1) determine phylogenetic relationships and date the origin of main amphibian lineages, (2) formulate a biogeographic scenario by associating phylogenetic divergences with plate-tectonic events, and (3) interprete these results in terms of the phylogenetic position of several fossil lineages. A statistically fundated molecular phylogeny should reconcile the opposing points of view of paleontologists, biogeographists and evolutionary biologists.