The hypothesis of reproductive compensation and its assumptions about mate preferences and offspring viability

Abstract

The Compensation Hypothesis says that parents and prospective parents attempt to make up for lowered offspring viability by increasing reproductive effort to produce healthy, competitive offspring and by increasing investment in less viable, but still-living progeny (parental effects). The hypothesis assumes that offspring viability is lower when individuals are constrained (often through sexual conflict) to breed with individuals they do not prefer. We review results of experimental tests of the offspring-viability assumption in Tanzanian cockroaches, fruit flies, pipefish, wild mallards, and feral house mice. Experimental constraints on mating preferences lowered offspring viability in each of the studies. Females breeding under constraints laid more eggs or gave birth to more young than females breeding without or with fewer constraints on their mating preferences, and males mating under constraints on their mate preferences ejaculated more sperm than males mating without constraints. The number of eggs laid or offspring born was higher when female choosers were experimentally constrained to reproduce with males they did not prefer. Constrained females may increase fecundity to enhance the probability that they produce adult offspring with rarer phenotypes with survival benefits against offspring generation pathogens. Similarly, ejaculation of more sperm when males are paired with females they do not prefer may be a mechanism that provides more variable sperm haplotypes for prospective mothers or that may provide nutritional benefits to mothers and zygotes. differential allocation ͉ fecundity ͉ sexual conflict ͉ constraints hypothesis T he Compensation Hypothesis (CH) (1, 2) says that parents and prospective parents increase reproductive effort and investments in offspring to make up for lowered offspring viability resulting from reproduction under constraints. It predicts what individuals do when they are unable to mate with preferred partners as often happens under sexual conflict, i.e., when individuals are constrained to reproduce with partners they do not prefer. The hypothesis assumes that (i) when constrained individuals have other options, they resist reproduction with partners they do not prefer, but sometimes resistance is unsuccessful and individuals then attempt to make the best of a bad job; and (ii) constraints on the free expression of mate preferences negatively affect offspring viability. In this work, we introduce the assumptions and predictions of the CH; in Results and Discussion we describe combined analyses over independent studies designed to test the assumptions and predictions of the CH, and we contrast our results with predictions from classical sexual selection.

Differential allocation in relation to mate song quality in the Bengalese finch

“…In contrast with the differential allocation hypothesis, the compensation hypothesis predicts enhanced reproductive investment of females that were mated to non-preferred males (Gowaty et al, 2007;Gowaty 2008). Because offspring viability was lower when females were forced to breed with non-preferred males, females compensated for this by increasing clutch size or egg mass (e.g.…”

Compensatory investment in zebra finches: females lay larger eggs when paired to sexually unattractive males

“…shortage of nutrients) than high genetic quality offspring, then it may pay females to increase their investment when paired to a male of low genetic quality. This investment pattern is called compensatory investment (CI ) and has been observed in a few studies (Saino et al 2002;Michl et al 2005;Navara et al 2006;Gowaty et al 2007). This is especially likely in a mating system with low reproductive skew, where even low-quality offspring will reproduce successfully.…”

Polyandry enhances offspring viability with survival costs to mothers only when mating exclusively with virgin males in Drosophila melanogaster

“…The differences indicate an advantage in egg number for M L females at younger ages and P E females at older ages, therefore, given our interest in offspring viability, we truncated the comparison of offspring viability to subjects less than 43 days old: On 28 of 36 days difference scores were positive indicating greater egg‐to‐adult survival for P E than M L females. Assuming that M L females had stronger constraints on mate choice than P E females, the over‐lifetime observations of P E advantage over M L are consistent with the hypothesis (Anderson et al., 2007; Gowaty, 2008; Gowaty et al., 2007a) saying that females breeding under constraints compensate for expected deficits in health of offspring by increasing egg number.…”