Effects of Selection Parameters on Effective Population Sizes for Mass Selection
1987
In a random mating population of constant size, the effective population size (Ne) is a function of the number of parents (n) and the variance of their gamete contributions (Vk). The objective of this study was to conduct a computer simulation of mass selection of maternal and paternal parents in order to determine the effects of n, selection intensity (i), and heritability (H²) on Vk. The computer simulation consisted of four independent runs of 10 consecutive repetitions of simulated mass selection at n = 20, 40, and 80, i = 1/40 and 4/40, and h² = 0.0 − 1.0/0.1. The mean Vk increased linearly as h² increased from 0.0 to 1.0, resulting in a decrease in the ratio Nₑ/n from 0.984 to 0.577 for i = 1/40, and from 0.986 to 0.741 for i = 4/40. The effect of n on Vₖ was small. The results of this study indicate that equating Nₑ with n will lead to a substantial underestimation of the cumulative effects of random drift and inbreeding depression when mass selection is carried out for a moderately or highly heritable trait.
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