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Updated: Jul 8, 2026

Mass-Rearing and Molecular Studies in Tortricidae Pest Insects
Published on: March 25, 2022
Rarity of males in pea aphids results in mutational decay
Jennifer A Brisson1, Sergey V Nuzhdin
1Section of Ecology and Evolution, University of California, Davis, CA 95616, USA. jabrisson@ucdavis.edu
Abstract:
When females can reproduce without males, do males become an evolutionarily weaker sex whose genes experience mutational decay? We addressed this hypothesis in aphids, whose reproduction alternates between parthenogenetic and sexual forms: Over the course of a year, there can be 10 to 20 generations of asexual females but only a single, if any, generation with males. We used microarray analyses to identify male-biased, asexual female-biased, and neutral genes. Interspecific comparisons reveal accelerated evolution of male-biased genes, and intraspecific polymorphisms exhibit a significant excess of nonsynonymous coding variation in male-biased genes. We conclude that the ability of females to reproduce asexually without males reduces selection constraints on male-based genes, resulting in their mutational decay.
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