Genetic and Phylogeographic Structure of Tabanus bromius L., 1758 (Diptera: Tabanidae) in Turkey Fauna

Current distribution of a species is a result of its long evolutionary history, and its genetic and phylogeographic structure is governed by its ecological requirements and historical events. In this thesis, genetic diversity and phylogeographic structuring of Tabanus bromius L., 1758 (Diptera: Tabanidae) sampled from Turkey, Croatia and Iran were investigated. For this purpose, a 686 base pair fragment of mitochondrial cytochrome oxidase I gene and 1339 nucleotide-fragment of the nuclear ITS region (ITS1-5.8S rRNA- ITS2) were amplified, sequenced and data sets were analyzed. Two hundred thirty-three individuals of T. bromius generated 169 COI haplotypes and 247 samples produced 90 distinct alleles. Both data sets displayed a high level of genetic diversity. Higher haplotype diversity as compared to low nucleotide diversity, the high number of singleton and private haplotypes/alleles detected in T. bromius populations implied historical population expansion. Results of phylogenetic analysis using maximum parsimony, maximum likelihood and bayesian inference generated geographically significant groupings of lineages with regards to the entrance of the species into Anatolia and the location of the major geographic barriers. According to the current data, it seems that the species entered Turkey from Caucasia and Iran. Molecular clock applied to the COI lineages implied that T. bromius diverged from the outgroup species nearly 8,83 million years ago, around the end of the Miocene era. Main clade formation of the species coincides with Pliocene, and it seems that the Quaternary changes were also responsible for major structuring of the Turkish T. bromius populations.