Female multiple mating as a genetic bet‐hedging strategy when mate choice criteria are unreliable

Abstract

Female multiple mating (or polyandry) is considered to act as a genetic bet‐hedging mechanism, by which females can reduce the assessment error in regard to mates’ genetic quality when only uncertain information is available. In spite of frequent verbal arguments, no theoretical examination has been carried out to determine the effectiveness of bet‐hedging by multiple mating. In the present paper, I show that three factors, female population size, remating costs and environmental fluctuation, all affect the effectiveness of bet‐hedging. A mathematical model predicts that bet‐hedging effectively works only in small populations, and computer simulations were used to confirm this prediction. The results of simulations differed according to the degree of environmental fluctuation. In relatively stable environments, if there is no remating cost, the fixation probability of a multiple mating strategy is slightly higher than that of a single mating strategy, independent of female population size. However, with very slight fitness costs, multiple mating drastically loses its advantage as population size increases, and almost always becomes extinct within large populations. This means that the evolution of polyandry solely by the mechanism of bet‐hedging is unlikely in stable environments. However, in unpredictable environments, or when negative frequency‐dependent selection on fitness‐related loci is introduced, a multiple mating strategy is sometimes successful against a single mating strategy, even if it entails a small fitness cost. Therefore, female multiple mating may possibly evolve only in these limited conditions. In most cases, some deterministic mechanisms such as postcopulatory sperm selection by multiply mated females (or direct ‘material’ benefits) are more reasonable as the evolutionary causes of polyandry.

Multiple mating and its relationship to brood size in pregnant fishes versus pregnant mammals and other viviparous vertebrates

“…Regardless of its number of mates, each male or female in any sexual species presumably can enhance its genetic fitness by choosing one or more mates of the highest possible genetic quality. Thus, for example, despite any inherent fecundity limitations imposed by pregnancy, any sire in a male-pregnant species or any dam in a female-pregnant species might be under selection to seek multiple mates for any of the following reasons: more "nuptial gifts," fertilization insurance against the risk that a mate is sterile, higher genetic diversity among the half-sibling progeny with its brood (21,22), better chances of finding a genetically compatible mate, or more opportunities to imbue at least some of the offspring with "good genes" for viability (23,24). Of course, multiple mating by either sex can incur appreciable fitness costs as well, such as the time and energy required to secure mates and the increased chance of contracting a sexually transmitted disease.…”

Marital Dissolution and Child Educational Outcomes in San Borja, Bolivia

“…Evidence from high-income countries tends to find that low levels of education reduces marital stability (Tzeng and Mare 1995;Lyngstad 2004). Finally, there may also be fitness benefits to having genetic diversity in offspring, which increases the possibility that some offspring survive in a fluctuating environment (Jennions and Petrie 2000), but modeling work suggests that this benefit only exists under a narrow set of assumptions (Yasui 2001).…”

Mate selection in captive-breeding rockfishes Sebastes spp.: inference from parentage analysis and the major histocompatibility complex (MHC)

“…Considering the close relationship of copper and quillback rockfishes (Hyde & Vetter 2007), the absence of evidence of multiple paternity in quillback rockfish in the present study may be a consequence of low sample size, rather than evidence that it does not occur. Multiple paternity may be a bet-hedging strategy for rockfishes when a female's knowledge of mate selection criteria is imperfect (Yasui 2001). Such a strategy may improve the genetic diversity of offspring from a single female, thereby improving the odds that some fraction of her larvae encounter favorable environmental conditions and survive (Cushing 1990, Hyde et al 2008, Van Doornik et al 2008.…”

“…Ultimately, the decision whether or not to mate appears to lie with the female (Hyde et al 2008). Multiple mating, with up to 4 different fathers, has been demonstrated in 13 different rockfish species to date, and may be a common bethedging strategy in the genus when mate selection criteria are uncertain or incomplete (Yasui 2001, Hyde et al 2008, Sogard et al 2008, Van Doornik et al 2008, Blanco Gonzalez et al 2009). As consequences of selective mate choice by females and multiple paternity, a population of organisms that experiences sweepstakes recruitment, such as rockfishes, may experience enhanced genetic diversity and avoid the loss of rare alleles, may see diminished impacts of inbreeding depression, and may benefit from increased effective population size (Hedgecock 1994).…”