Female social preference for males that have evolved via monogamy: evidence of a trade-off between pre- and post-copulatory sexually selected traits?

Abstract

When females mate with multiple males both pre- and post-copulatory sexual selections occur. It has been suggested that females benefit from polyandry when better-quality males are successful in sperm competition and sire high-quality offspring. Indeed, studies of experimental evolution have confirmed that sperm competition selects for both increased ejaculate quality and elevated offspring viability. Fewer investigations have explored whether these fitness benefits are evident beyond early life-history stages. Here, I used house mice ( Mus domesticus ) from selection lines that had been evolving for 25 generations under either polygamy or monogamy to test whether females preferred males from lines that had evolved with sperm competition. Males from the polygamous lines had previously been shown to achieve a fitness advantage under semi-natural conditions, deeming them to be of high genetic quality and leading to the a priori expectation that females would prefer males that had evolved with sperm competition compared with males that had not. Contrary to expectation, the data showed that sexually receptive females spent more time associating with males from the monogamous lines. This unexpected but interesting result is discussed in relation to sperm competition theory that predicts a trade-off between male investment in pre- and post-copulatory sexually selected traits.

A competitive environment influences sperm production, but not testes tissue composition, in house mice

“…Modifications to traits that were not measured may have resulted in trade‐offs going undetected (e.g. see Firman, in mice and Simmons et al ., for a general review). However, as an ethical requirement our experimental animals were provisioned with unlimited access to food, water and shelter.…”

Evolutionary change in testes tissue composition among experimental populations of house mice

“…Therefore, a reduction in testes interstitial tissue, and consequently a reduction in the density of Leydig cells, could result in a reduction in testosterone production and influence the quality or frequency of scent‐marks produced by males. A recent study has revealed that sexually receptive females spent more time associating with males from the monogamous populations compared to males from the polygamous populations, suggesting that these males have a precopulatory advantage that could be attributable to an intrinsic quality associated with the scents that they produce (Firman ). The divergence in testes tissue composition among males evolving with and without sperm competition reported here certainly warrants further research into evolutionary trade‐offs between pre‐ and postcopulatory sexually selected traits.…”

Stabilizing selection on sperm number revealed by artificial selection and experimental evolution

“…) can be estimated in experimental‐evolution studieses (e.g., Simmons and Garcia‐Gonzalez ; Crudgington et al. ; Firman and Simmons ; Firman ; Perry et al. ).…”

“…Artificial selection allows to shed light on previously hidden covariances, either positive or negative, among sexually selected traits, or to highlight the limits imposed by selection on other fitness components (e.g., Wilkinson and Reillo 1994;Von Schantz et al 1995;Pitnick and Miller 2000;Ahuja and Singh 2008;Wigby et al 2009;Booksmythe et al 2016). Alternatively, the evolutionary response of sexual traits to specific conditions imposed by the experimenter (Kawecki et al 2012) can be estimated in experimental-evolution studieses (e.g., Simmons and Garcia-Gonzalez 2008;Crudgington et al 2009;Firman and Simmons 2011;Firman 2014;Perry et al 2016).…”