Pre-pleistocene refugia and differentiation between populations of the Caucasian salamander (Mertensiella caucasica)

A 350-bp fragment of the mitochondrial cytochrome-b gene was sequenced in the Caucasian salamander, Mertensiella caucasica, representing 10 populations from across its range along the Black Sea coast. Five haplotypes were discovered among 65 fragments analyzed, differing at 2-50 positions, The highest differentiation between haplotypes was observed in animals from the eastern part of the species' range (Borjomi) compared to those from the remainder of the species' range. Randomly amplified nuclear DNA revealed a pattern of spatial genetic variation similar to that of the mitochondrial genome. M, caucasica, as currently known, represents two evolutionary lineages that evolved independently, perhaps since the lower Pliocene, These lineages represent tare, possibly to be described as species, distributed in the Borjomi area in central Georgia and in southwestern Georgia and northeastern Turkey. The multivariate analysis of morphological data did not reveal significant differences between the taxa, However, substantial morphological differentiation was observed within both lineages, showing parallel patterns in body proportions and coloration patterns. This variation is possibly associated with extant ecological conditions. Salamanders with reduced pigmentation from southwestern Georgia were not genetically distinguishable from neighboring populations. (C) 2000 Academic Press.