Accelerated adaptive evolution on a newly formed X chromosome.

Sex chromosomes originated from ordinary autosomes, and their evolution is characterized by continuous gene loss from the ancestral Y chromosome. Here, we document a new feature of sex chromosome evolution: bursts of adaptive fixations on a newly formed X chromosome. Taking advantage of the recently...

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Autores principales:	Doris Bachtrog, Jeffrey D Jensen, Zhi Zhang
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2009
Materias:	Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/95385474ddad4a10885043c2978d3289
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spelling	oai:doaj.org-article:95385474ddad4a10885043c2978d32892021-11-25T05:34:13ZAccelerated adaptive evolution on a newly formed X chromosome.1544-91731545-788510.1371/journal.pbio.1000082https://doaj.org/article/95385474ddad4a10885043c2978d32892009-04-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/19402745/?tool=EBIhttps://doaj.org/toc/1544-9173https://doaj.org/toc/1545-7885Sex chromosomes originated from ordinary autosomes, and their evolution is characterized by continuous gene loss from the ancestral Y chromosome. Here, we document a new feature of sex chromosome evolution: bursts of adaptive fixations on a newly formed X chromosome. Taking advantage of the recently formed neo-X chromosome of Drosophila miranda, we compare patterns of DNA sequence variation at genes located on the neo-X to genes on the ancestral X chromosome. This contrast allows us to draw inferences of selection on a newly formed X chromosome relative to background levels of adaptation in the genome while controlling for demographic effects. Chromosome-wide synonymous diversity on the neo-X is reduced 2-fold relative to the ancestral X, as expected under recent and recurrent directional selection. Several statistical tests employing various features of the data consistently identify 10%-15% of neo-X genes as targets of recent adaptive evolution but only 1%-3% of genes on the ancestral X. In addition, both the rate of adaptation and the fitness effects of adaptive substitutions are estimated to be roughly an order of magnitude higher for neo-X genes relative to genes on the ancestral X. Thus, newly formed X chromosomes are not passive players in the evolutionary process of sex chromosome differentiation, but respond adaptively to both their sex-biased transmission and to Y chromosome degeneration, possibly through demasculinization of their gene content and the evolution of dosage compensation.Doris BachtrogJeffrey D JensenZhi ZhangPublic Library of Science (PLoS)articleBiology (General)QH301-705.5ENPLoS Biology, Vol 7, Iss 4, p e82 (2009)
institution	DOAJ
collection	DOAJ
language	EN
topic	Biology (General) QH301-705.5
spellingShingle	Biology (General) QH301-705.5 Doris Bachtrog Jeffrey D Jensen Zhi Zhang Accelerated adaptive evolution on a newly formed X chromosome.
description	Sex chromosomes originated from ordinary autosomes, and their evolution is characterized by continuous gene loss from the ancestral Y chromosome. Here, we document a new feature of sex chromosome evolution: bursts of adaptive fixations on a newly formed X chromosome. Taking advantage of the recently formed neo-X chromosome of Drosophila miranda, we compare patterns of DNA sequence variation at genes located on the neo-X to genes on the ancestral X chromosome. This contrast allows us to draw inferences of selection on a newly formed X chromosome relative to background levels of adaptation in the genome while controlling for demographic effects. Chromosome-wide synonymous diversity on the neo-X is reduced 2-fold relative to the ancestral X, as expected under recent and recurrent directional selection. Several statistical tests employing various features of the data consistently identify 10%-15% of neo-X genes as targets of recent adaptive evolution but only 1%-3% of genes on the ancestral X. In addition, both the rate of adaptation and the fitness effects of adaptive substitutions are estimated to be roughly an order of magnitude higher for neo-X genes relative to genes on the ancestral X. Thus, newly formed X chromosomes are not passive players in the evolutionary process of sex chromosome differentiation, but respond adaptively to both their sex-biased transmission and to Y chromosome degeneration, possibly through demasculinization of their gene content and the evolution of dosage compensation.
format	article
author	Doris Bachtrog Jeffrey D Jensen Zhi Zhang
author_facet	Doris Bachtrog Jeffrey D Jensen Zhi Zhang
author_sort	Doris Bachtrog
title	Accelerated adaptive evolution on a newly formed X chromosome.
title_short	Accelerated adaptive evolution on a newly formed X chromosome.
title_full	Accelerated adaptive evolution on a newly formed X chromosome.
title_fullStr	Accelerated adaptive evolution on a newly formed X chromosome.
title_full_unstemmed	Accelerated adaptive evolution on a newly formed X chromosome.
title_sort	accelerated adaptive evolution on a newly formed x chromosome.
publisher	Public Library of Science (PLoS)
publishDate	2009
url	https://doaj.org/article/95385474ddad4a10885043c2978d3289
work_keys_str_mv	AT dorisbachtrog acceleratedadaptiveevolutiononanewlyformedxchromosome AT jeffreydjensen acceleratedadaptiveevolutiononanewlyformedxchromosome AT zhizhang acceleratedadaptiveevolutiononanewlyformedxchromosome
_version_	1718414591583584256

Accelerated adaptive evolution on a newly formed X chromosome.

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