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Within-population Y-linked genetic variation for lifespan in Drosophila melanogaster
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
2015 (English)In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 28, no 11, 1940-1947 p.Article in journal (Other academic) Published
Abstract [en]

The view that the Y chromosome is of little importance for phenotypic evolution stems from early studies of Drosophila melanogaster. This species’ Y chromosome contains only 13 protein coding genes, is almost entirely heterochromatic, and is not necessary for male viability. Population genetic theory further suggests that non-neutral variation can only be maintained at the Y chromosome under special circumstances. Yet, recent studies suggest that the D. melanogaster Y chromosome trans-regulates hundreds to thousands of X and autosomal genes. This finding suggests that the Y chromosome may play a far more active role in adaptive evolution than has previously been assumed. To evaluate the potential for the Y chromosome to contribute to phenotypic evolution from standing genetic variation, we test for Y-linked variation in lifespan within a population of D. melanogaster. Assessing variation for lifespan provides a powerful test because lifespan i) shows sexual dimorphism, which the Y is primarily predicted to contribute to, ii) is influenced by many genes, which provides the Y with many potential regulatory targets, and iii) is sensitive to heterochromatin remodelling, a mechanism through which the Y chromosome is believed to regulate gene expression. Our results show a small but significant effect of the Y chromosome, and thus suggest that the Y chromosome has the potential to respond to selection from standing genetic variation. Despite its small effect size, Y-linked variation may still be important, in particular when evolution of sexual dimorphism is genetically constrained elsewhere in the genome.

Place, publisher, year, edition, pages
2015. Vol. 28, no 11, 1940-1947 p.
Keyword [en]
intralocus sexual conflict, longevity, sex chromosomes, sexual dimorphism, Y chromosome
National Category
Evolutionary Biology
Research subject
Biology with specialization in Evolutionary Genetics
URN: urn:nbn:se:uu:diva-258982DOI: 10.1111/jeb.12708ISI: 000364641900003PubMedID: 26230387OAI: oai:DiVA.org:uu-258982DiVA: diva2:842928
Swedish Foundation for Strategic Research Carl Tryggers foundation Swedish Research CouncilGerman Research Foundation (DFG), SCHI 1188/1-1
Available from: 2015-07-23 Created: 2015-07-23 Last updated: 2015-12-17Bibliographically approved
In thesis
1. The genetic architecture of sexual dimorphism
Open this publication in new window or tab >>The genetic architecture of sexual dimorphism
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Phenotypic differences between the sexes evolve largely because selection favours a different complement of traits in either sex. Theory suggests that, despite its frequency, sexual dimorphism should be generally constrained from evolving because the sexes share much of their genome. While selection can lead to adaptation in one sex, correlated responses to selection can be maladaptive in the other. In this thesis I use Drosophila to examine the extent to which the shared genome constrains the evolution of sexual dimorphism and whether the sex chromosomes might play a special role in resolving intralocus sexual conflict.

Gene expression data shows that intersexual genetic correlations are generally high, suggesting that genes often affect both sexes. The intersexual genetic correlation is negatively associated with sex-bias in expression in D. melanogaster, and the rate of change in sex-bias between D. melanogaster and six closely related species, showing that a sex-specific genetic architecture is a prerequisite for the evolution of sex difference. In further studies I find that genetic variance affecting lifespan is found in the male-limited Y chromosome within a population, which could offer a route to the evolution of further sexual dimorphism in lifespan, though the amount of variance was small suggesting adaptive potential from standing genetic variance is limited. Genetic variance on the X chromosome is also expected to be depleted once the sex chromosomes evolve, but here I find no evidence of depletion in either sex. Dosage compensation does not appear to double the male X-linked genetic variance, but this effect may be complex to detect. Finally, the X chromosome appears to be enriched for sex-specific genetic variance, and the consequences of this are explored using a variety of analytical methods to test biologically meaningful aspects of G-matrix structure.

In summary, this thesis suggests that the evolution of sexual dimorphism is generally constrained by the shared genome, but intralocus sexual conflict could be resolved by novel mutations on the Y chromosomes, and by standing sex-specific genetic variance on the X chromosome. It highlights a special role for the X chromosome in the evolution of sexual dimorphism.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 56 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1264
Drosophila melanogaster, evolution, intralocus sexual conflict, sex chromosomes, sexually antagonistic selection, sexual dimorphism
National Category
Evolutionary Biology
urn:nbn:se:uu:diva-258986 (URN)978-91-554-9278-6 (ISBN)
Public defence
2015-09-18, Lindahlsalen, Evolutionary Biology Centre, Norbyvägen 18, Uppsala, 10:00 (English)
Available from: 2015-08-28 Created: 2015-07-23 Last updated: 2015-10-01

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