Male fitness increases when females are eliminated from gene pool: implications for the Y chromosome.
Because the two sexes share a common gene pool while performing many different biological functions, mutations benefiting one sex may not accumulate due to counter selection in the other sex. In these experiments 99% of a haploid genome of Drosophila melanogaster was constrained to segregate like a male-limited Y chromosome for 41 generations, thereby eliminating potential counter selection in females. The synthetic Y chromosomes rapidly accumulated genetic variation that increased male fitness and decreased female fitness. The survival and fertility of females declined when they were mated to males expressing the synthetic Y chromosomes. These results suggests that opposing selection between the sexes may substantially interfere with sex-specific adaptation. They also demonstrate how intersexual evolutionary conflict can lead to perpetual degeneration of the Y via genetic hitchhiking of deleterious mutations.
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Department of Biology, Earth and Marine Sciences Building, University of California, 1156 High Street, Santa Cruz, CA 95064, USA.
D000818:Animals; D001522:Behavior, Animal; D005075:Biological Evolution; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D008297:Male; D014998:Y Chromosome