Polyandrous females benefit by producing sons that achieve high reproductive success in a competitive environment

Abstract

Females of many taxa often copulate with multiple males and incite sperm competition. On the premise that males of high genetic quality are more successful in sperm competition, it has been suggested that females may benefit from polyandry by accruing 'good genes' for their offspring. Laboratory studies have shown that multiple mating can increase female fitness through enhanced embryo viability, and have exposed how polyandry influences the evolution of the ejaculate. However, such studies often do not allow for both female mate choice and male -male competition to operate simultaneously. Here, I took house mice (Mus domesticus) from selection lines that had been evolving with (polygamous) and without (monogamous) sperm competition for 16 generations and, by placing them in free-ranging enclosures for 11 weeks, forced them to compete for access to resources and mates. Parentage analyses revealed that female reproductive success was not influenced by selection history, but there was a significant paternity bias towards males from the polygamous selection lines. Therefore, I show that female house mice benefit from polyandry by producing sons that achieve increased fitness in a semi-natural environment.

Polyandry in dragon lizards: inbred paternal genotypes sire fewer offspring

“…From these studies, we have learnt that when females mate with multiple males, it may increase their fitness (Tregenza and Wedell 1998; Fisher and Lara 1999; Byrne and Whiting 2008) and that of their offspring (Klemme et al. 2008; Firman 2011). An adaptive but largely untested explanation for polyandry is that females minimize inbreeding depression by biasing fertilization toward sperm from genetically compatible males or males with good genes (Tregenza and Wedell 2002; Bretman et al.…”

Rapid adaptation to mammalian sociality via sexually selected traits

“…Intrasexual competition can also have independent effects on offspring fitness, and mice with high competitive ability often have offspring with higher fitness than their non-dominant counterparts [7]. Finally, post-copulatory selection during controlled polyandrous mating has been shown to improve offspring fitness relative to controlled monogamous mating [8,9]. These studies show that the components of sexual selection affect offspring fitness under certain conditions.…”

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

“…Alternatively, or additionally, variation in male ultrasonic vocalization could have influenced female social interest and inspection behaviour [24,25]. The ability of 'monogamous' males to better attract females could explain why they gained paternity representation in ca 50% of litters that were produced in free-ranging enclosures [19]. However, the ultimate success of males that had evolved with sperm competition suggests that high-quality ejaculates provide a greater fitness return than investments in pre-copulatory traits [19].…”

“…The ability of 'monogamous' males to better attract females could explain why they gained paternity representation in ca 50% of litters that were produced in free-ranging enclosures [19]. However, the ultimate success of males that had evolved with sperm competition suggests that high-quality ejaculates provide a greater fitness return than investments in pre-copulatory traits [19]. Future research will directly explore trade-offs between pre-copulatory traits (e.g.…”

“…These results lead to a priori expectation that females would prefer males that had evolved with sperm competition versus males that had evolved under a monogamous regime. Indeed, when released into free-ranging enclosures and forced to compete for mates, males from the polygamous lines experienced high reproductive success at the expense of 'monogamous' males (sired 80% of the offspring [19]). In this study, I was unable to directly examine mating preferences and behaviour.…”