HETEROZYGOSIS IN AN ALLOGAMOUS POPULATION WITH PARTIAL SELF POLLINATION AND IN AN AUTOGAMOUS POPULATION WITH PARTIAL CROSSING

Abstract

Genetic or induced male sterility has been suggested as a mean of increasing genetic variability in autogamous plants. On the other hand, in some allogamous populations certain proportion of selfing exists. Thus, the two situations are apparently the same. However, in the autogamous population androsterile plants obviously can not be selfed. It is expected also that in the allogamous population heterozygocity would decrease due to partial selfing, while in the autogamous population it would increase due to partial crossing. The objective of this research is to compare quantitatively the heterozygosis in the two types of populations. A formula that estimates the heterozygosis for any generation in the allogamous population with partial selfing is derived. This formula is compared with the one that calculates the heterozygosis in the autogamous population with partial crossing. It is shown that even with 50 % of crossing, heterozygosis in the long run increases in only one-third with respect to the original population of homozygous plants. Finally, for the same proportion of partial selfing in the two kinds of populations, the difference between their levels of heterozygosis decreases as generations advance.