Beerli, P., H. Hotz, E., and T. Uzzell. 1996. Geologically dated sea barriers calibrate a protein clock for Aegean water frogs. Evolution 50(4): 1676-1687.
Abstract -- Reliable estimates of phylogenetic relationships and divergence times are a crucial
requirement for many evolutionary studies, but are usually difficult because fossils
are scarce and their interpretation is often uncertain. Frogs are fresh water animals
that generally are unable to cross salt water barriers (their skin is readily permeable
to both salt and water). The geologically-determined ages of salt water barriers
that isolate related frog populations thus provide an independent measure of the
minimum date of genetic divergence between pairs of such populations. For the
genetically well-studied western Palearctic water frogs (Rana esculenta group), the
Aegean region provides an ideal area for determining the relationship between
genetic divergence and time of spatial isolation, using a nested set of geologically-
determined isolation times (12,000 y, 200,000 y, 1.8 My, 2-3 My, and 5.2 My).
Key words: rate of evolution, molecular clock, phylogeny, protein electrophoresis, frogs, Rana esculenta group, geology, Aegean region