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Mating theory (Hubbell & Johnson 1987, American Naturalist, 130, 91–112; Gowaty & Hubbell 2009, Proceedings of the National Academy of Sciences, U.S.A., 106, 10017–10024) says that reproductive decisions of individuals are flexibly expressed and adaptive. It also makes the following five predictions about polyandry. (1) Demography determines within-population, between-female variation in mating rates. That is, (a) an individual's encounters with potential mates, (b) an individual's risk of death, (c) the number of potential mates in the population, (d) the distribution of fitness under random mating, and (e) for nonvirgins, the duration of any postcopulation period of nonreceptivity together determine within-population, between-female variation in mating rate. (2) When demography is dynamic, there is unlikely to be an optimal female mating rate. That is, when potential mates enter or leave the pool of potential mates or when decision makers face survival risks from conspecifics, predators, parasites or pathogens, females who adaptively adjust their reproductive decisions in real-time outcompete females whose behaviour is fixed. (3) Female multiple mating often increases production of adult offspring through enhanced offspring viability (indirect fitness) and between-generation lineage success. (4) Polyandry will increase female exposure to pathogens and thus decrease female survival (direct fitness cost) unless females use environmental or intrinsic resources or opportunities to reduce survival risks. (5) Under many circumstances, female remating may enhance female survival (direct fitness benefit). Future research attention will focus on how intrinsic, ecological and social opportunities/constraints affect the likelihood of polyandry and its fitness effects for particular females. Future researchers may also consider that polyandrous mating is sometimes sexually collaborative and cooperative, rather than always sexually antagonistic. [Copyright &y& Elsevier]

Constraints theory says that when individuals reproduce with nonpreferred partners, they will have offspring of lower viability than when individuals reproduce with preferred partners. To test this, we performed mate preference trials free of experimenter biases about what traits in males make them attractive to females. We eliminated social interactions that could manipulate or obscure females'' choices, including interactions between males, between females, and between the sexes. We then randomly placed each female with either her nonpreferred or preferred male in breeding trials to determine how components of fitness for breeders and offspring viability varied. Offspring viability (the percentage of eggs surviving to 45 days posthatch) and mother productivity (mean number of offspring at 45 days posthatch) were significantly lower when mothers reproduced with their nonpreferred partner than with their preferred partners. This study adds to the growing list of species in which reproduction with nonpreferred partners is known to be costly to breeder and offspring fitness. It is among the few studies of birds and the only study of a species with forced copulation showing fitness deficits for offspring and mothers from enforced reproduction with nonpreferred males. [Copyright &y& Elsevier]

The compensation hypothesis (CH) says that when impediments to the expression of mate preferences occur so that reproduction is with nonpreferred (NP) partners, mothers with NP mates compensate for lower-viability offspring through enhanced investment. Previously, we tested an assumption of the CH and showed that offspring viability was significantly lower when mothers reproduced with NP mates. Here we report tests of the CH. Egg mass differed significantly by mother agemate category. Second-year mothers in NP pairings laid significantly heavier eggs than second-years mothers in preferred (P) pairings; mean egg mass of first-year mothers with NP or P mates did not differ. However, mean egg mass per mother and mean number of eggs per mother were positively and significantly related. Thus, there was no trade-off between egg size and egg number for any category of mother. By fledging age, duckling performance, quality and condition were significantly lower for first-year mothers with NP mates compared with those for mothers in the other categories. Second-year, but not first-year mothers, successfully compensated for predictable deficits in offspring viability from reproduction with NP males. This is the first study showing that mothers compensate for viability deficits in offspring resulting from reproduction with NP partners. [Copyright &y& Elsevier]

When social constraints on the expression of mate preferences are absent, variation in offspring viability is predicted to favour females and males that display mate preferences. Earlier studies showed that female and male house mice, Mus domesticus, tested individually and mated with preferred (P) partners had higher reproductive success and better progeny performance than individuals mated with nonpreferred (NP) partners. Here we tested the effects of mutual mate preferences on reproductive success, offspring viability and performance. We conducted mate preference tests and created four types of reproductive pairings. One involved females and males that preferred each other (P–P); the second type had females that preferred the male but the male did not prefer the female (P–NP); the third had females that did not prefer the male but the male did prefer the female (NP–P). The last set consisted of females and males that did not prefer each other (NP–NP). We measured components of fitness for breeders (reproductive success) and offspring viability (birth-to-weaning viability and weight variation) as well as measures of offspring performance. There were no statistical differences in reproductive success of breeders or offspring viability and quality (weight variation) among the four types of pairings. There were, however, consistent differences between P–P versus NP–NP matings. The number of pups weaned, time to first litter, birth-to-weaning viability, pup body weight at birth and weaning, and the growth rates for pups of both sexes were consistently greater for progeny from P–P matings than NP–NP matings. Significant differences occurred among the four mating types in dominance of sons during aggression trials, nest construction and predator avoidance. Progeny from P–P matings displayed behaviour associated with higher fitness more often than progeny from NP–NP matings. These data show that breeders produce more highly competent progeny, most likely to survive, when social constraints on the expression of mate preferences in both sexes are relaxed.Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

We report experimental results consistent with the hypothesis that constraints on the expression of male mating preferences affect breeder fitness, offspring viability and performance. If constraints on the expression of mating preferences are common, tests of fitness variation associated with mate preferences must eliminate as many constraints on mate preferences as possible. We tested whether male mate preferences influenced breeder fitness, offspring performance and viability in typically polygynous house mice, Mus domesticus, from a feral source population. Our ‘free mate choice’ trials not only eliminated female preferences, male–male and female–female competition, but also our best guesses of the traits mediating choosers'' preferences. Males mated with their preferred (P) females sired more litters than males mated with their nonpreferred (NP) females. Offspring viability was significantly lower when males'' reproduced with females they did not prefer compared with females they did prefer. Adult sons of males that mated with their P females were socially dominant to sons of males that mated with their NP females. Adult offspring from P pairings built better nests than offspring from NP pairings. The slope of the survivorship curve for P offspring was significantly higher than for NP offspring. These results showed (1) males'' mate preferences affected their fitness, (2) males that mated with females they preferred produced more litters than males that mated with females they did not prefer, and (3) their offspring were significantly more viable and performed significantly better on standardized performance tests. This is the first demonstration of fitness benefits of male choice behaviour in a mammal species with typical paternal investment. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

Studies the effects of free female mate choice on the reproductive success, offspring viability and performance of house mice. Elimination of other mechanisms of reproductive competition; Effect of mate choice on nesting; Influence of mate choice on mothers' health.

Discusses the results of a study which examined how nestbox availability affects extra-pair fertilization and conspecific nest parasitism in eastern bluebirds, Sialia sialis. First experimental evidence for birds demonstrating that individuals engage in genetically effective alternative reproductive tactics; Increase in the rate of conspecific nest parasitism after removal.

Compares the natal dispersal patterns between male and female eastern bluebirds. Difference in the initial reproductive success of philopatric and dispersing second-year males and females; Effects of adult turnover on dispersal of individual offspring; Possibility of high dispersal costs associated with mortality.

Presents a hypothesis for social monogamy among passerine birds. Factors contributing to social monogamy among animals; Behavior of males and females in social monogamy.

Male mate choice is an often neglected aspect of sexual selection studies. While theory predicts that females should exhibit mate choice due to their comparatively greater investment in gametes, males may also exhibit mate choice for a variety of reasons, including seeking mates with greater fecundity. Furthermore, males may exhibit discriminant or indiscriminate mate choice as a function of their own intrinsic characteristics, such as body size or condition. Here we experimentally evaluated male Jamaican field cricket, Gryllus assimilis , mating preferences using randomly selected females and determined how both male and female morphology (body size and residual mass) and male signalling behaviour influence male mate preference. Results show that male crickets exhibit mating preferences, with larger males tending to exhibit more consistent mate preferences than smaller males. Contrary to predictions, males did not prefer larger or relatively heavier females, suggesting that males may not be basing their choosiness on these proxy measures of female fecundity. Our findings highlight the need for continued research on male mate choice and identifying the intrinsic characteristics of both sexes that drive them. [ABSTRACT FROM AUTHOR]

Indirect fitness benefits hypotheses suggest that offspring of preferred mates should exhibit greater survival or reproductive success. For example, good genes hypotheses propose that female mating preferences are mediated by secondary sexual traits because they honestly reflect the ability to pass on genes that will enhance offspring survival or reproduction. Conversely, complementary genes hypotheses propose that mating preferences are mediated by complementary genes because they enhance offspring viability. While these two research traditions are not strict alternatives and both may operate simultaneously, they have never been tested together. Here we explore the multiple potential underlying factors influencing mating preference evolution in Jamaican field crickets, Gryllus assimilis . After evaluating female preferences for randomly selected males, we tested whether preferred males differed from nonpreferred males in their body size, relative mass or mate attraction signals. We then mated females to their preferred or nonpreferred partners and tested offspring viability. Results revealed: (1) females preferred larger males, (2) larger females oviposited more eggs, (3) neither morphology nor mate attraction signalling explained variation in offspring viability, and (4) mating with a preferred partner did not enhance offspring viability. Overall, in our current study population, cricket mate preferences were inconsistent with complementary genes and good genes hypotheses for indirect fitness benefits. Our current research explores whether male secondary sexual traits honestly reflect the ability to pass on genes that enhance offspring reproduction. [ABSTRACT FROM AUTHOR]

Individual variation in sexual fidelity and extrapair paternity (EPP) is widely attributed to environmental heterogeneity, but the only variables known to be influential are food abundance and density of conspecific breeders (potential extrapair partners). Habitat structure is thought to impact EPP but is rarely measured and, when considered, is usually confounded with food abundance and predation pressure. To sidestep these confounds, we tested whether EPP is associated with habitat structure variables and with local conspecific density in a species whose nesting habitat is not used for feeding and lacks predators. In a blue-footed booby, Sula nebouxii , colony, the probability of EPP in a female's nest was highest in parts of the study plot where there were few obstacles to locomotion, and was quadratically related to local density of sexually active males, even though local males did not sire the EP chicks. The probability of a male breeder siring EP (extrapair) chicks elsewhere was quadratically related to local density of sexually active males around his nest. From these patterns we infer that both sexes may foray for EP interactions, that males and females nesting at intermediate density are most likely to be accessed by forayers, and that obstacles in the vicinity of a female's nest constrain access of foraying males. To our knowledge, this is the first demonstration that individual variation in EPP is associated with habitat structure in the absence of confounding variation in food availability, predation pressure or breeder quality, and the first evidence that EPP opportunities of female and male breeders are reduced by high density of conspecific breeders above a particular threshold. [ABSTRACT FROM AUTHOR]