Abstracts (first author)
Divergence and gene flow in Lissotriton newts
Historical patterns and consequences of genetic exchange between hybridizing species are poorly understood, but new genomic and analytical tools promise a rapid progress. We will present the results of research on historical demography and genome-wide patterns of gene flow between hybridizing newts Lissotriton montandoni (Lm) and L. vulgaris (Lv). These newts are characterized by a long history of genetic exchange, as evidenced by the mitochondrial DNA (mtDNA) data. Multiple, spatially and temporally distinct introgression events from Lv resulted in complete mtDNA replacement in Lm. We used various classes of molecular nuclear markers to obtain information about the extent and historical patterns of gene flow between the two species. Fifteen microsatellite loci and 139 coding SNPs surveyed in multiple populations demonstrated a very limited recent admixture in the nuclear genome. Genome-wide patterns of long-term gene flow were assessed by analyzing of over 300 000 SNPs derived from high-throughput transcriptome sequencing. The inferences based on the joint two-population allele frequency spectrum revealed an extensive, asymmetric gene flow from Lv to Lm and models allowing for demographic changes and temporal variation in the strength of gene flow provided best fit to the data. The species distribution modeling based on contemporary and historical climatic data suggests that temporal variation in gene flow between Lm and Lv may be linked to range changes the newts experienced during the Pleistocene climatic oscillations. Sequences of over 50 nuclear markers collected throughout the species ranges and analyzed within the coalescent framework provided evidence for genomic heterogeneity in gene flow. Our study demonstrates the complexity of long-term genetic exchange between hybridizing species and the power of new sequencing technologies for a comprehensive characterization of interspecific gene flow in non-model organisms possessing huge genomes.