Genetic Introgression in Populations of Two Related Species Adalia frigida (Schneider, 1792) and Adalia bipunctata (Linnaeus, 1758) (Coleoptera: Coccinellidae) in the Zone of Sympatry

The haplotype diversity of mtDNA of the circumpolar species of ladybirds Adalia frigida collected in Yakutsk and Salekhard was studied. Based on the analysis of the nucleotide sequences of the cox1 gene, 18 mitochondrial haplotypes were identified, of which 14 were new. Of the 18 haplotypes of A. frigida , two (H32 and H9) are the most common. In the Salekhard region, the range of A. frigida overlaps with that of another closely related species, A. bipunctata . The value of divergence in the cox1 gene between A. frigida and A. bipunctata reaches 4.1–4.3% and corresponds to the level of differences characteristic of closely related species. These species are able to interbreed, and the share of hybrid specimens ( A. frigida and A. bipunctata ) in Salekhard is 56.5%. Hybridization between A. frigida and A. bipunctata led to mutual mitochondrial introgression, which resulted in the acquisition of the H1 haplotype by the A. frigida beetles and the H9 haplotype by the A. bipunctata beetles.