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Sibling rivalry: Males with more brothers develop larger testes

When females mate with multiple partners in a reproductive cycle, the relative number of competing sperm from rival males is often the most critical factor in determining paternity. Gamete production is directly related to testis size in most species, and is associated with both mating behavior and...

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Autores principales: Fisher, Heidi S., Hook, Kristin A., Weber, W. David, Hoekstra, Hopi E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145022/
https://www.ncbi.nlm.nih.gov/pubmed/30250695
http://dx.doi.org/10.1002/ece3.4337
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author Fisher, Heidi S.
Hook, Kristin A.
Weber, W. David
Hoekstra, Hopi E.
author_facet Fisher, Heidi S.
Hook, Kristin A.
Weber, W. David
Hoekstra, Hopi E.
author_sort Fisher, Heidi S.
collection PubMed
description When females mate with multiple partners in a reproductive cycle, the relative number of competing sperm from rival males is often the most critical factor in determining paternity. Gamete production is directly related to testis size in most species, and is associated with both mating behavior and perceived risk of competition. Deer mice, Peromyscus maniculatus, are naturally promiscuous and males invest significantly more in sperm production than males of P. polionotus, their monogamous sister‐species. Here, we show that the larger testes in P. maniculatus are retained after decades of enforced monogamy in captivity. While these results suggest that differences in sperm production between species with divergent evolutionary histories can be maintained in captivity, we also show that the early rearing environment of males can strongly influence their testis size as adults. Using a second‐generation hybrid population to increase variation within the population, we show that males reared in litters with more brothers develop larger testes as adults. Importantly, this difference in testis size is also associated with increased fertility. Together, our findings suggest that sperm production may be both broadly shaped by natural selection over evolutionary timescales and also finely tuned during early development.
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spelling pubmed-61450222018-09-24 Sibling rivalry: Males with more brothers develop larger testes Fisher, Heidi S. Hook, Kristin A. Weber, W. David Hoekstra, Hopi E. Ecol Evol Original Research When females mate with multiple partners in a reproductive cycle, the relative number of competing sperm from rival males is often the most critical factor in determining paternity. Gamete production is directly related to testis size in most species, and is associated with both mating behavior and perceived risk of competition. Deer mice, Peromyscus maniculatus, are naturally promiscuous and males invest significantly more in sperm production than males of P. polionotus, their monogamous sister‐species. Here, we show that the larger testes in P. maniculatus are retained after decades of enforced monogamy in captivity. While these results suggest that differences in sperm production between species with divergent evolutionary histories can be maintained in captivity, we also show that the early rearing environment of males can strongly influence their testis size as adults. Using a second‐generation hybrid population to increase variation within the population, we show that males reared in litters with more brothers develop larger testes as adults. Importantly, this difference in testis size is also associated with increased fertility. Together, our findings suggest that sperm production may be both broadly shaped by natural selection over evolutionary timescales and also finely tuned during early development. John Wiley and Sons Inc. 2018-07-22 /pmc/articles/PMC6145022/ /pubmed/30250695 http://dx.doi.org/10.1002/ece3.4337 Text en © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Fisher, Heidi S.
Hook, Kristin A.
Weber, W. David
Hoekstra, Hopi E.
Sibling rivalry: Males with more brothers develop larger testes
title Sibling rivalry: Males with more brothers develop larger testes
title_full Sibling rivalry: Males with more brothers develop larger testes
title_fullStr Sibling rivalry: Males with more brothers develop larger testes
title_full_unstemmed Sibling rivalry: Males with more brothers develop larger testes
title_short Sibling rivalry: Males with more brothers develop larger testes
title_sort sibling rivalry: males with more brothers develop larger testes
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145022/
https://www.ncbi.nlm.nih.gov/pubmed/30250695
http://dx.doi.org/10.1002/ece3.4337
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