Multiple paternity is common in many species. While its benefits for males are obvious, for females they are less clear. Female indirect benefits may include acquiring ‘good genes’ for offspring or increasing litter genetic diversity. The nutria (Myocastor coypus) is a successful invasive species. In its native habitat, it is polygynous, with larger and more aggressive males monopolizing paternity. Here, using culled nutria we genetically examined multiple paternity in-utero and found a high incidence of multiple paternity and maintenance of the number of fathers throughout gestation. Moreover, male fetuses sired by the prominent male have higher testosterone levels. Despite being retained, male fetuses of ‘rare’ fathers, siring commonly only one of the fetuses in the litter, have lower testosterone levels. Considering the reproductive skew of nutria males, if females are selected for sons with higher future reproductive success, low testosterone male fetuses are expected to be selected against. A possible ultimate explanation for maintaining multiple paternity could be that nutria females select for litter genetic diversity e.g., a bet-hedging strategy, even at the possible cost of reducing the reproductive success of some of their sons. Reproductive strategies that maintain genetic diversity may be especially beneficial for invasive species, as they often invade through a genetic bottleneck.
Bibliographical noteFunding Information:
We are grateful to Devorah Matas for her devoted support. We thank KKL-JNF for funding the nutria project and supporting the Hula Research Center. We further wish to thank the KKL-JNF Agmon Hula Park. We also wish to thank our undergraduate student assistants and volunteers, particularly Ester Shavalian, Or Danino, Noam Noylander and Nour Daief. We thank Gili Greenbaum for helpful comments. We further thank all members of the Koren lab and Anat Levi and the Vortman lab for their support throughout the project.
This work was supported by Keren Kayemeth LeIsrael (KKL-JNF) research fund (90-50-000-17).
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