University of Oulu

Sultanova, Z., Downing, P. A., & Carazo, P. (2023). Genetic sex determination, sex chromosome size and sex-specific lifespans across tetrapods. Journal of Evolutionary Biology, 36, 480– 494.

Genetic sex determination, sex chromosome size and sex-specific lifespans across tetrapods

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Author: Sultanova, Zahida1; Downing, Philip A.2,3; Carazo, Pau4
Organizations: 1School of Biological Sciences, University of East Anglia, Norwich, UK
2Department of Biology, Lund University, Lund, Sweden
3Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
4Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.1 MB)
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Language: English
Published: John Wiley & Sons, 2023
Publish Date: 2023-07-12


Sex differences in lifespan are ubiquitous across the tree of life and exhibit broad taxonomic patterns that remain a puzzle, such as males living longer than females in birds and vice versa in mammals. The prevailing unguarded X hypothesis explains sex differences in lifespan by differential expression of recessive mutations on the X or Z chromosome of the heterogametic sex, but has only received indirect support to date. An alternative hypothesis is that the accumulation of deleterious mutations and repetitive elements on the Y or W chromosome might lower the survival of the heterogametic sex (‘toxic Y’ hypothesis). Here, we use a new database to report lower survival of the heterogametic relative to the homogametic sex across 136 species of birds, mammals, reptiles and amphibians, as expected if sex chromosomes shape sex-specific lifespans, and consistent with previous findings. We also found that the relative sizes of both the X and the Y chromosomes in mammals (but not the Z or the W chromosomes in birds) are associated with sex differences in lifespan, as predicted by the unguarded X and the ‘toxic Y’. Furthermore, we report that the relative size of the Y is negatively associated with male lifespan in mammals, so that small Y size correlates with increased male lifespan. In theory, toxic Y effects are expected to be particularly strong in mammals, and we did not find similar effects in birds. Our results confirm the role of sex chromosomes in explaining sex differences in lifespan across tetrapods and further suggest that, at least in mammals, ‘toxic Y’ effects may play an important part in this role.

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Series: Journal of evolutionary biology
ISSN: 1010-061X
ISSN-E: 1420-9101
ISSN-L: 1010-061X
Volume: 36
Issue: 2
Pages: 480 - 494
DOI: 10.1111/jeb.14130
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: PC was supported by a Ramón y Cajal Fellowship (RYC-2013-12998), Plan Nacional I + D + i Excelencia Research Grants (CGL2014-58722-P and CGL2017-89052-P) from the Plan Nacional I + D + i by the Spanish Government, co-funded by the European Regional Development Fund, a SEJI research grant by the Generalitat Valenciana (SEJI/2018/037) and a 2018 Leonardo Grant for Researchers and Cultural Creators from the BBVA Foundation. ZS was supported by the ‘Atracció de Talent’ grant (Universitat de València).
Copyright information: © 2022 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.