The Herpetological Journal

Authors: Maletzky, Andreas; Mikulíček, Peter; Franzen, Michael; Goldschmid, Alfred; Gruber, Hans-Jürgen; Horák, Ales & Kyek, Martin

Abstract: In the area between south-eastern Bavaria (Germany) and Upper Austria the distribution ranges of northern (Triturus cristatus) and Italian crested newts (T. carnifex) are narrowly sympatric and a hybrid zone has been suggested on the basis of morphological data. In our study of 35 autochthonous populations in this region, we compared distribution patterns and hybridization on the basis of one morphological (Wolterstorff index, WI) and two molecular (cytochrome b, microsatellites) markers. Furthermore, we studied the status of an introduced T. carnifex population, originating from Croatia and thriving in a locality near Munich for more than 15 years. Tissue samples from Bavarian populations (preserved phalanges) were already available from a previous study. Austrian samples were gained non-destructively, by collecting buccal cells with sterile cotton buds. Results showed good concordance for all markers in most populations. Average WI values per population were within the range of the species T. cristatus and T. carnifex. Six populations from Salzburg and Upper Austria showed intermediate index values in males and females. Applying standard measures of genetic diversity within populations as well as Bayesian analysis of population structure, we detected admixed populations and individuals in three regions of Salzburg and Upper Austria. No autochthonous population of T. carnifex could be detected in Bavaria. The hybrid zone is probably unimodal, with hybrid individuals predominating in the centre. As the present-day distribution ranges of both species in the surveyed area are fragmented and populations are heavily reduced in numbers, we only can observe their remains. The analysis of molecular markers revealed considerable genetic uniformity. The studied area has been colonized by a limited number of individuals and probably less often than areas with slightly higher diversity. Hybrid zones in the study region were most probably formed by one genetically different T. carnifex population and two different T. cristatus populations. The allochthonous T. carnifex population in Isen (Bavaria) showed no signs of interbreeding with native T. cristatus. The assumption that this population was based on offspring from one pair is highly questionable according to our data.

Keywords: MICROSATELLITES, HYBRID ZONE, MTDNA, SALAMANDRIDAE, ADMIXTURE, TRITURUS CRISTATUS SUPERSPECIES, BAYESIAN ANALYSIS, WOLTERSTORFF INDEX