Two clades of north European pool frogs Rana lessonae identified by cytochrome b sequence analysis

A 410 base-pair region of the mitochondrial cytochrome b (cytb) gene, including the coding region for amino acids 44–179, was amplified and sequenced from a total of 53 pool frogs (Rana lessonae) sampled in nine European countries across the species' biogeographical range. Just two haplotypes were found, differing by single base pair (G–A transition) at a codon second position, corresponding to a conservative (serine–asparagine) change at amino acid 75. Only haplotype A (serine 75) was found in the samples from Italy, Hungary, Switzerland, Poland, Sweden, Norway and Britain (including museum specimens). Only haplotype B (asparagine 75) was found in France, and there were equal numbers of A and B haplotypes in a small sample from the Netherlands. Comparisons with other ranid cytb sequences together with an absence of stop codons indicated that the sequences were mitochondrial rather than nuclear copies. Using these north European cytb sequences and three more from other work based on individuals from Italy, Ukraine and Luxembourg, we discuss haplotype distribution with respect to the phylogeography of R. lessonae.