Genetic Distance and Heterozygosity Estimates in Electrophoretic Studies: Effects of Sample Size

Metazoan parasite species richness and genetic variation among freshwater fish species: cause or consequence?

“…richness in ®sh and other vertebrates, but ®sh body size is the most pervasive covariate among these [22,37]. We eliminated several ®sh species from our data set because they had been investigated at fewer than 20 loci and estimates of their genetic variability may have been imprecise [18,19]. In a further analysis in which we lowered our standards to include all ®sh species that had been investigated at more than 15 loci (this procedure allowed inclusion of species from three additional ®sh families: Centrarchidae, Gasterosteidae, and Clupeidae), the negative relationship between parasite species richness and heterozygosity remained approximately the same (r=À0.311, n = 42 sets of contrasts, P = 0.046).…”

“…We used two estimates of polymorphism, based on two di erent criteria for polymorphism: P99, for which the frequency of the most common allele had to be i0.99, and P95, for which the frequency of the most common allele had to be i0.95. Because of the high variance in singlelocus polymorphism among loci, estimates of genetic variation are far more severely in¯uenced by the number of loci sampled than by the number of individuals examined [18,19]. Thus, following Nei's [18] suggestions, estimates were only used if at least 20 loci had been investigated from at least ®ve individual ®sh, or if at least two individuals had been used and scored for at least 25 loci.…”

Biochemical variation in roe deer (Capreolus capreolus L.): are r-strategists among deer genetically less variable than K-strategists?

“…Generally the number as well as the composition of enzyme systems and serum proteins studied seem to have an important influence on estimates of genetic variation and genetic divergence (see e.g. Johnson, 1974;Ward, 1977;Sarich, 1977;Gorman and Renzi, 1979;Lewontin, 1985;Hartl and Csaikl, 1987, for further discussion of this problem). While our results support Nevo's (1984) conclusion that generalist species are genetically more variable than specialist species they provide further evidence against the argument that comparatively large mammals should be genetically less variable than small mammals.…”

Genic differentiation and phylogenetic relationships within two New World bat genera

“…Previous studies have demonstrated empirically that identity coefficients are affected somewhat by small samples sizes, with distance being magnified due to sampling error [7]. However, in the present study, the Nei identity values (Tables 3 and 4) are used only as an estimate of genetic divergence.…”