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The divergence of reproductive strategies is an important development toward intraspecific diversification. We describe contrasting spawning patterns of parapatric and sympatric Arctic charr forms in two interconnected lakes Kiryalta-3 and Kiryalta-4 in Transbaikalia for comparison to charr reproduction in nine more lakes of this region. In each Kiryalta lake, two charr forms (small and large) differing in growth and diet are present, in Kiryalta-3 they are morphologically more distinct than in Kiryalta-4. In Kiryalta-3, the spawning of the small form was recorded in autumn and spring suggesting two subpopulations; spawning time of the large form is unknown. In Kiryalta-4, both forms spawn in autumn. Overall, reproductive patterns of Transbaikalian charr vary greatly in spawning time, duration, location, depth, and bottom substrate. Different populations and sympatric forms spawn in early or late autumn, spring, summer, or during more than one season, including the littoral or profundal zone, over rocks or silt, and from 1–2 weeks to at least 7 months. Peak spawning time difference between sympatric forms can reach up to 5 months, and is correlated with morphological and genetic differences. Diversification of reproductive strategies largely contributed to the emergence of exceptionally high diversity of Transbaikalian charr.

Genetic variation at eight microsatellite loci was examined in 21 populations of Dolly Varden charrs, Salvelinus malma, representing five geographical regions (Kamchatka Peninsula, Sea of Okhotsk coast, Sea of Japan coast, Sakhalin Island, and Kuril islands). Hierarchical analysis of molecular variance showed that 11% (58% in terms of R-statistics) of the variation was distributed among of northern subspecies of Dolly Varden, Salvelinus malma malma and southern Asian Dolly Varden, S. m. krascheninnikovi while similar values were attributed to the among-regional level within northern Dolly Varden 9% (7%) and southern Asian Dolly Varden 11% (14%). Permutation-based tests indicated a mutational component to genetic differentiation based on allelic size variance and suggested that divergence of the two subspecies had occurred at least 3,000 generations ago. On large spatial scales (within the Asian range of the species), populations clustered according to their geographical location. On smaller scales (within regions and subregions) correlation between genetic and geographic distances was not significant. Northern Dolly Varden has higher allelic diversity and more private alleles than southern subspecies, this probably indicating differences in demographic history.

Chars of the genus Salvelinus, inhabiting lakes and lake-river systems, comprise morphological and ecological forms whose taxonomic status is under dispute. In the present work, we have examined genetic variation and divergence in various chars from the Kronotsky lake basin: the lacustrine chars (white, nose, and longhead) and riverine Dolly Varden Salvelinus malma. The study was conducted using analysis of allozyme and microsatellite loci, myogens, RAPD, and restriction analysis of two mtDNA segments. The estimates of heterozygosity at allozyme and microsatellite loci were similar to the corresponding parameters in populations of northern Dolly Varden and Arctic char. Heterozygote deficit was recorded in both samples of separate forms, and in the total sample of all chars from Kronotsky Lake. For allozyme and microsatellite loci, appreciable genetic differentiation among the samples of different char forms was found, which was comparable to that among the spatially isolated populations of northern Dolly Varden. This result indicates reproductive isolation among the char forms examined. However, this isolation is not complete, because no fixed differences between the forms by any of the genetic systems analyzed were found. The genetic differentiation among different forms of lacustrine chars, which corresponds to the interpopulation rather than interspecific level, is thought to be explained by their comparatively recent divergence.

Genetic parameters of pink salmon introduced into the White Sea basin in 1985 and 1998 were compared to the corresponding parameters of the donor population from the Ola River (Magadan oblast). The detected genetic differences indicate that colonization of a new area is accompanied by impoverishment of the gene pool of the native population. This effect was particularly marked in the odd-year broodline of pink salmon introduced in 1985. The probable causes of these genetic changes are discussed.