Within a Y-chromosome haplogroup defined by unique event mutations, variation in microsatellites can accumulate due to their rapid mutation. Estimates based on pedigrees for the Y-chromosome microsatellite mutation rate are 3 or more times greater than the same estimates from evolutionary considerations. We show by simulation that the haplogroups that survive the stochastic processes of drift and extinction accumulate microsatellite variation at a lower rate than predicted from corresponding pedigree estimates; in particular, under constant total population size, the accumulated variance is on average 3–4 times smaller.

Waples (2015) has suggested a formula for the Wahlund effect in a case of unequal contribution of samples from genetically different populations that relates Wright’s inbreeding coefficient, F _IS, and normalized variance in allele frequencies between populations, F _ST. I generalize this relationship to a case of multiple alleles and multiple populations not assuming Hardy–Weinberg ratios prior to mixing. This can help to evaluate the impact of a Wahlund effect on heterozygote deficiency relative to other factors such as null alleles, nonrandom mating, or selection. It is suggested that Wahlund effect cannot be an important factor of deviations from Hardy–Weinberg proportions in natural populations in the majority of instances, but it can have a substantial contribution to heterozygote deficiency in a population that has low genetic diversity compared to that among immigrants or in mixed samples that contain comparable fractions of individuals from genetically different populations.

Chum salmon populations in the Russian Far East have a complex multi-level genetic structure. A total of 53 samples (2446 fish) were grouped into five major regional clusters: the southern Kurils, eastern Sakhalin, southwestern Sakhalin, the Amur River, and a northern cluster. The northern cluster consists of chum salmon populations from a vast geographical region, including Chukotka, Kamchatka, and the continental coast of the Sea of Okhotsk. However, the degree of its genetic differentiation is low, 1.9%. In contrast, the southern population cluster exhibits much higher variation; for example, differentiation between chum salmon groups within Sakhalin Island reaches 4.6%, and the differentiation between Iturup Island and Sakhalin Island chum salmon is 7.7%. This suggests that southern populations of Asian chum salmon have a more ancient evolutionary history than northern populations. In contrast to the available data, our study indicates a great deviation of southwestern Sakhalin populations from other Sakhalin chum salmon. The Russian Far East chum salmon are genetically diverse and show statistically significant differentiation even within small geographic localities. This can be used to assign samples of unknown origins to definite local populations.