An evolutionary cost of separate genders revealed by male-limited evolution.
Theory predicts that intralocus sexual conflict can constrain the evolution of sexual dimorphism, preventing each sex from independently maximizing its fitness. To test this idea, we limited genome-wide gene expression to males in four replicate Drosophila melanogaster populations, removing female-specific selection. Over 25 generations, male fitness increased markedly, as sexually dimorphic traits evolved in the male direction. When male-evolved genomes were expressed in females, their fitness displayed a nearly symmetrical decrease. These results suggest that intralocus conflict strongly limits sex-specific adaptation, promoting the maintenance of genetic variation for fitness. Populations may carry a heavy genetic load as a result of selection for separate genders.
Prasad
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Department of Biology, Queen's University at Kingston, Biosciences Complex, 116 Barrie Street, Ontario K7L 3N6, Canada. prasad@biology.queensu.ca
Bedhomme
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S
Day
T
T
Chippindale
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AK
D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D008297:Male; D011995:Recombination, Genetic; D012727:Sex Characteristics