Genetic variation and its causes in the crested newt, Triturus carnifex (Laurenti, 1768), from Italy (Caudata : Salamandridae)

We studied genetic variation in 107 individuals from 12 Italian populations of the crested newt, Triturus carnifex, by horizontal starch-gel electroph oresis to test the hypothesis of disjunction along the Central Apennine, as has been found in other animals. Twenty-eight presumptive loci were eviden ced, 10 of which were monomorphic. Gene diversity was found to be high for salamandrids (mean percentage of polymorphic loci = 46.4, mean expected het erozygosity = 0.048, mean <(F-ST)over bar> = 0.358) with about two-thirds d ue to within-population diversity. Both multidimensional scaling and neighb or-joining analyses on genetic distances (mean Nei's D = 0.131) between pop ulations showed that these can be divided into two units, distributed north and south of the Central Apennines, respectively. Within-population gene d iversity was found to be lower in the north-cluster, following a pattern of isolation-by-distance; this pattern was not observed in the south. We conc lude that historical events (possibly glaciations) divided the populations into the two cited units. The genetic structure of T. carnifex in central a nd southern Italy somewhat parallels that of T. italicus from the same area s, thus suggesting a common evolutionary pattern of variation.