Assessment of population differentiation using DNA fingerprinting and modified Wright's Fst-statistics

Abstract

Using our results and literature data on multilocus DNA fingerprinting, we propose a method of obtaining unbiased estimates of the between--population genetic similarity index and a measure of population subdivision based on modified Wright's FST-statistics. On the basis of multiple comparison T2 Hotelling's test and Holmes' procedure, the FST-statistics was applied to assess differentiation of four (Pacific and Atlantic) subpopulations of humpback whale Megaptera novaeangliae, six populations of California island gray fox Urocyon littoralis, and geographically isolated Ob' and Yakutia populations of Siberian white crane Crus leucogeranus. It was shown that the regional humpback whale subpopulations do not constitute a single panmictic unit (P < 10(-4)). The subdivision index of the Pacific and Atlantic populations expressed in terms of FST-statistics varied from 0.101 to 0.157. The differentiation estimates for the island fox populations, which ranged from 0.2109 to 0.4027, indicate that subdivision of these populations is a function of the distance between the islands, island size, and population size. In particular, the smallest and the greatest differences were found respectively between the populations of the geographically closest northern islands (FST = 0.2157, FST = 0.2109) and between those of the most distant northern and southern islands (FST = 0.4027, FST = 0.3869). Subdivision of the island populations with minimum areas and low population number was intermediate (FST = 0.3789). Mean values of heterozygosity, within-population genetic similarity index, and the number of coinciding fragments for two random individuals of Siberian white crane from the Ob' and Yakutia population were not statistically significantly different (P > or = 0.852, (P > or = 0.491, (P > or = 0.325). However, pairwise comparisons of mean FST values indicated that the differentiation estimates for samples from these populations fall within the limits of population subdivision (P = 0.01). The subdivision estimate (0.108-0.133) of various groups of Siberian white cranes is comparable to interregional subdivision of humpback whale. Based on the results of this study, we recommend the approach based on modified Wright's FST-statistics for studying genetic population structure aimed at detecting population subdivision.