[Relation between heterozygosity and fertility in Forest Nentzy and Nganasan tribes]

The relationship between heterozygosity for 13 polymorphic loci and fertility of women having passed the menopause was studied in two North-Siberian tribes: Forest Nentzy (N = 108) and Nganasans (N = 68). The number of pregnancies positively correlated with the individual heterozygosity (r = 0.2910 +/- 0.1063; P less than 0.01) in Forest Nentzy, while in Nganasans this correlation was absent. Women with the average level of individual heterozygosity were characterized by minimal values of variation in pregnancies' number and maximal Q index of realized fertility. It is concluded that the average level of individual heterozygosity is optimal for both tribes.