Molecular diversity and phylogeography of Andricus curtisii (Hymenoptera, Cynipidae) in Turkey

• Mitochondrial and nuclear DNA sequences of Andricus curtisii in Turkey showed high level of genetic diversity across Turkey.
• Phylogenetic and phylogeographic analyses supported an eastern origin of haplotypes/alleles.
• Analysis showed that a splitting event of ingroup haplotypes from the outgroup lineages predated the Pleistocene.
• Two major haplogroup formation of the ingroup sequences coincided with the oscillation in the early Pleistocene glaciations.

A 433-bp fragment of the mitochondrial cytochrome b gene and the entire nuclear ITS2 region were sequenced in an oak gall wasp species, Andricus curtisii, which represents 21 populations across its range in Turkey. Forty cytochrome b haplotypes and 63 ITS2 alleles were discovered among the 161 individuals studied. Remarkable genetic variation was detected in the species, with an average haplotype diversity (h) of 0.72 and 0.76 and an average nucleotide diversity (π) of 0.06 and 0.01 for the cyt b gene and the ITS region, respectively. Most populations were genetically distinct, possessing unique cytochrome b haplotypes. Maximum likelihood and Bayesian phylogenetic analyses and application of the haplotype network to both datasets revealed that the most basally located haplotypes/alleles were from the eastern part of Turkey. The detection of older sequences in the phylogenetic trees of the easterly located populations implied an eastern origin of the species. The application of a conventional insect mitochondrial DNA clock to the dataset suggested a splitting of ingroup haplotypes from the outgroup lineages predating the Pleistocene epoch and the formation of two major haplogroups that coincided with the oscillation of the early Pleistocene glaciations.