Adaptive meiotic drive in selfing populations with heterozygote advantage

The egalitarian allotment of gametes to each allele at a locus (Mendel's law of segregation) is a near-universal phenomenon characterizing inheritance in sexual populations. As exceptions to Mendel's law are known to occur, one can investigate why non-Mendelian segregation is not more common using modifier theory. Earlier work assuming sex-independent modifier effects in a random mating population with heterozygote advantage concluded that equal segregation is stable over long-term evolution. Subsequent investigation, however, demonstrated that the stability of the Mendelian scheme disappears when sex-specific modifier effects are allowed. Here I derive invasion conditions favoring the repeal of Mendelian law in mixed and obligate selfing populations. Oppositely-directed segregation distortion in the production of male and female gametes is selected for in the presence of overdominant fitness. The conditions are less restrictive than under panmixia in that strong selection can occur even without differential viability of reciprocal heterozygotes (i.e. in the absence of parent-of-origin effects at the overdominant fitness locus). Generalized equilibria are derived for full selfing. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

The phenomenon of equal allotment of gametes to each allele at a locus, known as Mendel's law of segregation, is a common feature in sexual populations. This study explores the exceptions to Mendel's law and investigates the reasons behind the rarity of non-Mendelian segregation using modifier theory. The results show that the stability of the Mendelian scheme disappears when sex-specific modifier effects are allowed, and invasion conditions favoring the repeal of Mendelian law are derived for different populations.