Abstracts (first author)
Occupation of a novel environmental niche via hybridization in Central Asian water frogs Pelophylax
Many animal groups inhabiting Central Asia (CA) have complex biogeography, shaped by Plio-Pleistocenic climate and geological events. Relatively recent aridization makes this region interesting from evolutionary perspective as it represents an ideal arena to study evolution of aquatic species as water frogs Pelophylax. Until recently, this genus was considered to be represented by a single species in CA, however our phylogenetic analysis of two mitochondrial and one nuclear loci revealed presence of two divergent water frog taxa: P. terentievi and P. sp., each inhabiting a distinct river drainage. Sympartic occurrence of the heterospecific mtDNA haplotypes in the interflow of these two rivers and presence of heterozygots for the nDNA locus pointed on existence of a complex hybrid zone. Subsequent analyses of 8 codominant loci with STRUCTURE and TESS confirmed presence of 2 distinct genotypic clusters (Fst=0.48) as well as area of their admixture. Inference of admixture classes (NEWHYBRIDS) and the cline analysis (CFit7) pointed on tension type of the hybrid zone. Further, the TESS spatial interpolation map combined with the mtDNA haplotypes distribution data pointed on a zone of unidirectional mitochondrial introgression from P. terentievi to the P. sp. population. We applied environmental niche modelling (MaxEnt) to verify how different are parental populations (n=24 of each P. terentievi and P. sp.) and ones with mt introgression (n=5), having used 19 bioclimatic and 13 other layers. The obtained prediction models were highly reliable (mean AUC=0.997). Mean winter temperature had unique and high (accounted for 36% of the predicted range) impact on the model of populations with introgressed mitochondrial DNA. Hence, we speculate that hybridization of the two divergent water frog species and subsequent introgression of heterospecific mitochondrial DNA into the marginal populations of P. sp. promoted them to occupy novel ecological niche.