Sex decreases the pleiotropic costs of local adaptation by purging hitchhiking load.

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Title: Sex decreases the pleiotropic costs of local adaptation by purging hitchhiking load.
Authors: Pai, Shreyas V. (AUTHOR), Humphrey, Parris T. (AUTHOR), Simonet, Camille (AUTHOR), Kosheleva, Katya (AUTHOR), Limdi, Anurag (AUTHOR), Desai, Michael M. (AUTHOR)
Source: Science. 4/23/2026, Vol. 392 Issue 6796, p415-420. 6p.
Subjects: Genetic recombination, Saccharomyces cerevisiae, Asexual reproduction, Evolutionary theories, Biological adaptation, Genetic load
Abstract: Understanding the evolutionary mechanisms that maintain sex despite its direct costs is a long-standing challenge. Previous work has shown that sexual recombination can accelerate adaptation, in part by separating beneficial mutations from deleterious hitchhikers. However, earlier studies focused on effects of sex in a constant environment. We show that recombination provides an advantage during changing conditions in promoting the evolution of generalist phenotypes by reducing pleiotropic costs caused by local adaptation. Using laboratory evolution in Saccharomyces cerevisiae, we show that hitchhiking load leads to pleiotropic costs and hence specialization in response to local adaptation in asexual but not sexual lineages. This provides evidence that sex can be maintained over long evolutionary timescales because it enables lineages to persist in the face of environmental change. Editor's summary: Sexual reproduction is a complex and costly undertaking for eukaryotes such as budding yeast, which can also divide asexually. The great advantage is that sexual recombination accelerates adaptation and leaves behind deleterious mutations. In an attempt to find out how sex is maintained, Pai et al. found that for yeast subjected to a changing growth environment, which is the norm for most organisms, recombination promotes the evolution of generalists. Sexual reproduction is thus maintained in the long term because it reduces the pleiotropic costs of local adaptation and permits the persistence of lineages. —Caroline Ash [ABSTRACT FROM AUTHOR]
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Database: Psychology and Behavioral Sciences Collection
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Abstract:Understanding the evolutionary mechanisms that maintain sex despite its direct costs is a long-standing challenge. Previous work has shown that sexual recombination can accelerate adaptation, in part by separating beneficial mutations from deleterious hitchhikers. However, earlier studies focused on effects of sex in a constant environment. We show that recombination provides an advantage during changing conditions in promoting the evolution of generalist phenotypes by reducing pleiotropic costs caused by local adaptation. Using laboratory evolution in Saccharomyces cerevisiae, we show that hitchhiking load leads to pleiotropic costs and hence specialization in response to local adaptation in asexual but not sexual lineages. This provides evidence that sex can be maintained over long evolutionary timescales because it enables lineages to persist in the face of environmental change. Editor's summary: Sexual reproduction is a complex and costly undertaking for eukaryotes such as budding yeast, which can also divide asexually. The great advantage is that sexual recombination accelerates adaptation and leaves behind deleterious mutations. In an attempt to find out how sex is maintained, Pai et al. found that for yeast subjected to a changing growth environment, which is the norm for most organisms, recombination promotes the evolution of generalists. Sexual reproduction is thus maintained in the long term because it reduces the pleiotropic costs of local adaptation and permits the persistence of lineages. —Caroline Ash [ABSTRACT FROM AUTHOR]
ISSN:00368075
DOI:10.1126/science.aec9708