Population genetic structure and phylogeography of the oak gall wasp Andricus chodjaii (Hymenoptera: Cynipidae) in Turkey as inferred from mitochondrial and nuclear DNA sequences

Abstract

Sequence data of mitochondrial cytochrome b gene and nuclear ITS2 region were used to assess genetic diversity, intraspecific phylogeography and population genetic structure of the oak gall wasp Andricus chodjaii from Turkey. We examined 293 individuals from 21 localities which generated 57 cyt b haplotypes and 8 ITS2 alleles. The average genetic diversity was 0.575 for cyt b and 0.202 ITS2, and the average nucleotide diversity 0.015 for cyt b gene and 0.001 for the ITS2 region. Phylogenetic analyses of cyt b haplotypes produced mostly similar topologies with geographically significant groupings. The ITS2 data provided less resolution without robust and apparent geographic structure. Population demographic analysis indicated that some eastern populations expanded, however, some others underwent either expansion or decline resulting in genetically structured populations. Molecular clock applied to the mtDNA data indicated that ingroup haplotypes diversified from the outgroup haplotypes around Early Pliocene. Further diversification events throughout Pleistocene resulted in major clade formations. It appears that geographic formations and glacial and interglacial cycles of Pleistocene were crucial for shaping the phylogeographic structure of A. chodjaii in Turkey.