Introgressive Hybridization in the Secondary Contact Area of the Atlantic Herring Clupea harengus and the Pacific Herring C. pallasii (Clupeidae): Ecological Basis, Geographical Structure, and Temporal Variability of the Hybridization Zone

Abstract The geographical structure and dynamics of introgressive hybridization with Atlantic herring Clupea harengus were studied for the Pacific herring Clupea pallasii based on long-term monitoring of genetic variation of C. pallasii from the White, Barents, and Kara seas using multivariate statistical analysis procedures in the Structure and NewHybrids programs. An unequal level of introgression of the Atlantic herring’s genes have been reported for the population of the White Sea summer-spawning and spring-spawning herring as well as for the Chesha-Pechora herring. The factors involved in supporting the hybridization of herring species in the zone of their secondary contact were considered. The predominant role of hybridization and introgression of genes in the formation of intraspecific genetic diversity of the Pacific herring was revealed.