Pre- and postcopulatory competition affect testes mass and organization differently in two monophyletic mole-rat species, georychus capensis and Fukomys damarensis

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Authors

Rainer, Sharna R.
Cameron, Elissa Z.
Edwards, Amy M.
Bennett, Nigel Charles
Thomas, Hannah Grace
Swanepoel, Daniel

Journal Title

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Volume Title

Publisher

Oxford University Press

Abstract

Sperm competition results from post-copulatory continuation of male–male competition for paternity. The level of sperm competition is predicted to be highest in species with greater polyandry and weakest in monogamous pairs. Sperm competition levels can be indexed using traits that reflect male investment in fertilization, particularly relative testes mass (RTM). However, the relationship between RTM and levels of sperm competition may also be influenced by precopulatory competition selecting for higher levels of testosterone, also produced by the testes. To test the relationship between RTM and both pre- and post-copulatory male–male competition we compared two bathyergid mole-rat species, the promiscuous Georychus capensis and the monogamous eusocial Fukomys damarensis. The promiscuous species had not only larger RTM, but also a greater proportion of spermatogenic tissue, maximizing germ cell production as well. Conversely, the eusocial species had smaller testes, but a higher proportion of interstitial tissue (which contains the androgenic Leydig cells) and higher levels of testosterone. Consequently, testicular traits as well as testes mass may be under selection, but these are not normally measured. More research is required on relative investment in different testicular traits in relation to both pre- and post-copulatory selection pressures.

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Keywords

Bathyergidae, Eusocial, Monogamous, Promiscuous, Spermatogenic tissue, Relative testes mass (RTM), Mole-rats, Georychus capensis, Cape mole-rat (Georychus capensis), Fukomys damarensis, Damaraland mole-rat (Fukomys damarensis), SDG-15: Life on land, SDG-03: Good health and well-being

Sustainable Development Goals

SDG-03:Good heatlh and well-being
SDG-15:Life on land

Citation

Rainer, S.R., Cameron, E.Z., Edwards, A.M. et al. 2023, 'Pre- and postcopulatory competition affect testes mass and organization differently in two monophyletic mole-rat species, Georychus capensis and Fukomys damarensis', Journal of Mammalogy, vol. 104, no. 5, pp. 993-1002. https://DOI.org/10.1093/jmammal/gyad021.