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A.J. Bateman (1948) hypothesized that a metric of sexual selection is in sex differences of intrasexual variance in number of mates (VNM). AJB predicted that (a) males have greater variance in reproductive success (VRS) than females; (b) males have greater VNM than females; and (c) a positive relationship between VNM and VRS is stronger among males. AJB used phenotypically observable mutations in offspring to identify parents and to count subjects' NM and RS. AJB's conclusions matched his predictions, later called "Bateman's Principles." Empirical challenges to his conclusions guided analyses herein. (a) AJB's analysis pseudo‐replicated sample sizes, violating a sexual selection assumption: That is, individuals must be in the same population to choose and compete. (b) AJB's methods overestimated subjects with no mates while underestimating subjects with one or more. (c) A replication (Gowaty et al., 2012) showed that offspring inheriting nametags from both parents often died before expressing adult phenotypes, proving some of AJB's methods produced biased data. Science historian Thierry Hoquet located AJB's archived, handwritten laboratory notes, photocopied, and transcribed them. We tested each of the 65 unique populations for expected combinations in offspring of parental mutations: 41.5% failed Punnett's tests: Offspring carrying nametags simultaneously from both parents were missing showing estimates of parents' NM and VNM were undercounted. 58.5% of populations met Punnett's expectations providing an unparalleled opportunity to re‐evaluate AJB's predictions. 34 unbiased populations had no sex differences in VRS; 37 had no sex differences in VNM. No sex differences in slopes of RS and NM occurred in any unbiased population. Regressions showed weak, positive, significant associations between VNM and VRS for females and males, contrary to AJB's prediction that the relationship would be positive in males but not in females. AJB's laboratory data are inconsistent with "Bateman's Principles." [ABSTRACT FROM AUTHOR]

ABSTRACT Male mating preferences are often a neglected aspect of studies on sexual selection. Male mating preferences may evolve if they provide males with direct-fitness benefits such as increased opportunity to fertilize more eggs or indirect-fitness benefits such as enhanced offspring survival. We tested these ideas using Jamaican field crickets, Gryllus assimilis, previously shown to exhibit male mating preferences. We randomly mated males to either their preferred or non-preferred potential mates and then asked whether mating treatment influenced egg oviposition or offspring viability. Preferred females were not significantly more fecund and did not produce more viable eggs or offspring than non-preferred females. Male mate preferences were therefore inconsistent with both the direct- and indirect-fitness benefits hypotheses under the conditions of our experiment. Our null results leave us with an open question about what is driving the evolution of mating preferences in male crickets. Future research should explore the whether the offspring of preferred females are more attractive, have stronger immune systems, and/or experience higher adult longevity. [ABSTRACT FROM AUTHOR]

A prominent hypothesis for polyandry says that male-male competitive drivers induce males to coerce already-mated females to copulate, suggesting that females are more likely to be harassed in the presence of multiple males. This early sociobiological idea of male competitive drive seemed to explain why sperm-storing females mate multiply. Here, we describe an experiment eliminating all opportunities for male-male behavioral competition, while varying females' opportunities to mate or not with the same male many times, or with many other males only one time each. We limited each female subject's exposure to no more than one male per day over her entire lifespan starting at the age at which copulations usually commence. We tested a priori predictions about relative lifespan and daily components of RS of female Drosophila melanogaster in experimental social situations producing lifelong virgins, once-mated females, lifelong monogamous, and lifelong polyandrous females, using a matched-treatments design. Results included that (1) a single copulation enhanced female survival compared to survival of lifelong virgins, (2) multiple copulations enhanced the number of offspring for both monogamous and polyandrous females, (3) compared to females in lifelong monogamy, polyandrous females paired daily with a novel, age-matched experienced male produced offspring of enhanced viability, and (4) female survival was unchallenged when monogamous and polyandrous females could re-mate with age- and experienced-matched males. (5) Polyandrous females daily paired with novel virgin males had significantly reduced lifespans compared to polyandrous females with novel, age-matched, and experienced males. (6) Polyandrous mating enhanced offspring viability and thereby weakened support for the random mating hypothesis for female multiple mating. Analyzes of nonequivalence of variances revealed opportunities for within-sex selection among females. Results support the idea that females able to avoid constraints on their behavior from simultaneous exposure to multiple males can affect both RS and survival of females and offspring. [ABSTRACT FROM AUTHOR]

Mate choice hypotheses usually focus on trait variation of chosen individuals. Recently, mate choice studies have increasingly attended to the environmental circumstances affecting variation in choosers' behavior and choosers' traits. We reviewed the literature on phenotypic plasticity in mate choice with the goal of exploring whether phenotypic plasticity can be interpreted as individual flexibility in the context of the switch point theorem, SPT (Gowaty and Hubbell ). We found >3000 studies; 198 were empirical studies of within-sex phenotypic plasticity, and sixteen showed no evidence of mate choice plasticity. Most studies reported changes from choosy to indiscriminate behavior of subjects. Investigators attributed changes to one or more causes including operational sex ratio, adult sex ratio, potential reproductive rate, predation risk, disease risk, chooser's mating experience, chooser's age, chooser's condition, or chooser's resources. The studies together indicate that 'choosiness' of potential mates is environmentally and socially labile, that is, induced - not fixed - in 'the choosy sex' with results consistent with choosers' intrinsic characteristics or their ecological circumstances mattering more to mate choice than the traits of potential mates. We show that plasticity-associated variables factor into the simpler SPT variables. We propose that it is time to complete the move from questions about within-sex plasticity in the choosy sex to between- and within-individual flexibility in reproductive decision-making of both sexes simultaneously. Currently, unanswered empirical questions are about the force of alternative constraints and opportunities as inducers of individual flexibility in reproductive decision-making, and the ecological, social, and developmental sources of similarities and differences between individuals. To make progress, we need studies (1) of simultaneous and symmetric attention to individual mate preferences and subsequent behavior in both sexes, (2) controlled for within-individual variation in choice behavior as demography changes, and which (3) report effects on fitness from movement of individual's switch points. [ABSTRACT FROM AUTHOR]

Female 'mating failures' seem a paradox similar to the paradox of polyandry. To illustrate the twin paradoxes of female mating failures and polyandry, we assume that individuals, not sexes, trade-off time available for mating with immediate fitness increments or decrements that would be conferred by alternative potential mates. We use Hubbell & Johnson's (1987) [analytical mating theory (H&J), the first sex-neutral null model of stochastic demography on variance in lifetime mating and adaptive behavior, as well as another sex-neutral null model, the Switch Point Theorem ( SPT) (Gowaty & Hubbell, 2009). The H&J mating theory and SPT predict adaptive behavior of individuals accepting and rejecting potential mates without recourse to scenarios for the evolution of sex differences via anisogamy or parental investment. Sex-neutral models begin with individuals, not sexes. Null models assume no pre-existing sex-specific adaptations. H&J's mating theory and the SPT are discrete time absorbing Markov models that count the times individuals enter states such as receptivity, mating, latency to onset to receptivity, and death. H&J's model and the SPT are analytical solutions for the variance in mating success and the variance in reproductive success, as well as for the fraction of potential mates that are acceptable as mates to a given individual when potential mates differ in the fitness that they would confer to a given mating partner. In H&J's model, there are only two qualities of mates; in the SPT, there are n qualities of mates, where n = the number of potential mates in the population. Thus, both models predict mating failures and multiple mating for both sexes under similar or different demographic circumstances, including the fitness background (the fitness distribution of the pool of potential mates) under which individuals make reproductive decisions. In addition, we conducted numerical experiments using DYNAMATE©, a dynamic, agent-based (object-oriented) simulation program that tracks dynamically the fate and interactions of all individuals in a single population over a reproductive season. DYNAMATE embodies the analytical solutions of the SPT as rules that determine individually adaptive reproductive decisions. With DYNAMATE we studied how moment-to-moment changes in demographic circumstances change individual behavior and trajectories of mating opportunities under the rules of the SPT that determined for each individual each of its adaptive (fitness enhancing) reproductive decisions. The models demonstrate that the pathways to life-long virginity and multiple mating reside in: (1) variation in individual lifespan; (2) variation in encounters with potential mates; (3) adaptive acceptance or rejection of potential mates as actual mates, which in the case of rejection of all encountered potential mates, results in life-long virginity, a 'fitness trap'; (4) opposite-sex acceptances or rejections of potential mates as mates; and/or (5) some combination of (1)-(4). The models make quantitative predictions about life-long failures to mate. Results are consistent with the conclusions that the paradoxical twin riddles of females failing to mate or mating multiply can occur without any appeal to or requirement for pre-existing fixed sex differences in 'choosy' or 'indiscriminate' behavior. It may be that the twin riddles of polyandry and female mating failures are only puzzling because the assumptions from parental investment and anisogamy theories about the fixed nature of female mating behavior are wrong. [ABSTRACT FROM AUTHOR]

We are unique In reporting a repetition of Bateman [Bateman AJ (1948) Heredity (Ed'inb) 2:349-368] using his methods of parentage assignment, which linked sex differences in variance of reproductive success and variance in number of mates in small populations of Drosophila melanogaster. Using offspring phenotypes, we inferred who mated with whom and assigned offspring to parents. Like Bateman, we cultured adults expressing dramatic phenotypes, so that each adult was heterozygous-dominant at Its unique marker locus but had only wild-type alleles at all other subjects' marker loci. Assuming no viability effects of parental markers on offspring, the frequencies of parental phenotypes In offspring follow Mendelian expectations: one-quarter will be double-mutants who Inherit the dominant gene from each parent, the offspring from which Bateman counted the number of mates per breeder; half of the offspring must be single mutants inheriting the dominant gene of one parent and the wild-type allele of the other parent; and one-quarter would inherit neither of their parent's marker mutations. Here we show that inviabillty of double-mutant offspring biased Inferences of mate number and number of offspring on which rest inferences of sex differences In fitness variances, Bateman's method overestimated subjects with zero mates, underestimated subjects with one or more mates, and produced systematically biased estimates of offspring number by sex. Bateman's methodology mismeasured fitness variances that are the key variables of sexual selection. [ABSTRACT FROM AUTHOR]

The good genes hypothesis states that choosers prefer individuals of high intrinsic quality to individuals of lower intrinsic quality. Variation in longevity is thought to reflect, in part, intrinsic quality differences of individuals in addition to the costs of mating and reproduction. Here we report longevity variation of Drosophila pseudoobscura, a species in which previous experiments have demonstrated that individual mate preferences (pre-touching mate assessments) of females and males are associated with enhanced numbers of eclosed (adult) offspring and higher egg-to-adult survival (offspring viability). Using mate assessment arenas and protocols similar to those in a previous experiment that demonstrated fitness benefits to breeders and their offspring of mating with individuals they preferred, we tested the following predictions: (i) preferred discriminatees live longer than non-preferred discriminatees; (ii) males live longer than females; and (iii) virgins live longer than mated individuals. The experiment yielded 938 individuals for longevity analysis. Sex and mating status affected longevity: males lived longer than females, virgin females lived longer than mated females, but there were no differences in longevity for mated and virgin males. Non-preferred discriminatees of both sexes survived as long as preferred discriminatees, a result inconsistent with the prediction of the good genes hypothesis for mate preferences. To our knowledge, this is the first demonstration of the cost of reproduction for females in D. pseudoobscura and of longevity variation of preferred and non-preferred discriminatees. [ABSTRACT FROM AUTHOR]

Polyandrous mating is common, but the benefits for females of polyandry remain controversial. To test whether mating with multiple males affects female fitness, we compared lifetime components of fitness of three experimental sets of Drosophila pseudoobscura females: monogamous females allowed to copulate one time (Moc); monogamous females held with a male over her entire life and experiencing many copulations (MMd; and polyandrous females with a different male over each day of their lives and also experiencing many copulations (PMC). Consistent with previous studies in this species, females in treatments in which multiple copulations occurred, MMC and PMC. had offspring with significantly higher egg-to-adult survival (i.e., offspring viability) and higher numbers of adult offspring (i.e., productivity) than Moc females, showing that multiple inseminations enhance offspring and mother fitness. In addition, although MMC females laid significantly more eggs than polyandrous (PMC) females, percent egg-toadult survival and number of adult offspring were higher for PMC than MMC females, showing that polyandrous mating enhances the fitness of females more than multiply mating with only one male. Inconsistent with the cost of reproduction, lifespan was not significantly longer for Moc females than for MMC or PMC females. To our knowledge, this is the first study to examine simultaneously in outbred WT Drosophila pseudoobscura the lifetime costs and benefits to females of polyandry. monogamy with a single copulation, and monogamy with repeat copulations. [ABSTRACT FROM AUTHOR]

The switch point theorem (SPT) is the quantitative statement of the hypothesis that stochastic effects on survival, mate encounter, and latency affect individuals' time available for mating, the mean and variance in fitness, and thus, originally favored the evolution of individuals able to make adaptively flexible reproductive decisions. The SPT says that demographic stochasticity acting through variation in (i) individual survival probability, s; (ii) individual encounter probability, e; (110 latency, I; (iv) the number of potential mates in the population, n; and (v) the distribution of fitness conferred, the w distribution, together affect average lifetime fitness, and induce adaptive switches in individual reproductive decisions. The switch point is the rank of potential mates at which focal individuals switch from accepting to rejecting potential mates, a decision rule that the SPT proves maximizes the average lifetime fitness of a focal individual under given values of ecological constraints on time. The SPT makes many predictions, including that the shape of the distribution of fitness conferred affects individual switch points. All else equal, higher probabilities of individual survival and encounter decrease the fraction of acceptable potential mates, such that focal individuals achieve higher average lifetime fitness by rejecting more potential mates. The primary prediction of the SPT is that each decision a focal individual makes is determined jointly by e, s, I, n, and the w distribution. [ABSTRACT FROM AUTHOR]

The reproductive compensation hypothesis says that individuals constrained by ecological or social forces to reproduce with partners they do not prefer compensate for likely offspring viability deficits. The reproductive compensation hypothesis assumes that (i) pathogens and parasites evolve more rapidly than their hosts, (ii) mate preferences predict variation in health and viability of offspring, (iii) social and ecological factors keep some individuals from mating with their preferred partners (some are constrained to mate with partners they do not prefer), (iv) all individuals may be induced to compensate, so that (v) variation in compensation is due to environmental and developmental factors affecting between-individual abilities to express compensatory mechanisms. Selection favouring compensation may act through variation in prezygotic physiological mechanisms, zygotic mechanisms, or parental care to eggs or young that enhance offspring health, increasing the likelihood that some offspring survive to reproductive age, often at a survival cost to the parents. Compensation may be through increased number of eggs laid or offspring born, a compensatory effort working during a single reproductive bout that sometimes will match the number of offspring surviving to reproductive age produced by unconstrained parents during the same bout. The reproductive compensation hypothesis therefore predicts trade-offs in components of fitness for breeders, such that parents constrained to mating with a nonpreferred partner, but who compensate sometimes match their current productivity (number of offspring at reproductive age) to unconstrained parents (those breeding with their preferred partners), and, when all else is equal, die faster than unconstrained parents. The reproductive compensation hypothesis emphasizes that reproductive competition is not just between constrained and unconstrained individuals, but also among constrained individuals who do and do not compensate. The reproductive compensation hypothesis may thus explain previously unexplained between-population and within-population, between-individual variation in reproductive success, survival, physiology and behaviour. [ABSTRACT FROM AUTHOR]

Bateman's (1948) study showing greater variances in number of mates and reproductive success in male than female Drosophila melanogaster is a foundational paper in sexual selection. Here we show for the first time that his methods had flaws, including the elimination of genetic variance, sampling biases, miscalculations of fitness variances, statistical pseudo-replication, and selective presentation of data. We conclude that Bateman's results are unreliable, his conclusions are questionable, and his observed variances are similar to those expected under random mating. Despite our analysis, we do not intend this article as a criticism of Bateman; he accomplished his work without modern computational tools, and his approach was groundbreaking emphasizing the significance of fitness variance for sexual selection. However, this reanalysis has implications for what counts as evidence for sexual selection and we believe that our concerns should be of interest to contemporary students of sexual selection. We call for repetitions of Bateman's study using modern statistical and molecular methods. [ABSTRACT FROM AUTHOR]

Using Drosophila pseudoobscura, we tested the hypothesis that social constraints on the free expression of mate preferences, by both females and males, decrease offspring viability and reproductive success of mating pairs. Mate preference arenas eliminated intrasexual combat and intersexual coercion. The time female and male choosers spent in arena tests near either of two opposite-sex individuals measured the preferences of choosers. We placed choosers in breeding trials with their preferred or nonpreferred discriminatee when they met the minimum criteria for showing the same preference in two consecutive tests. There was no statistically significant difference in the frequency of female and male choosers meeting minimal preference criteria. There was a significant difference between female and male choosers for offspring viability, with female choice having the greater effect, but there was not a significant difference in the overall reproductive success of male and female choosers. There were significant differences in fitness between matings to preferred and nonpreferred partners. Female and male choosers paired with their nonpreferred discriminatees had offspring of significantly lower viability, as predicted by the constraints hypothesis. Reproductive success, our measure of overall fitness, was greater when males or females mated with the partner they preferred rather than the one they did not prefer. [ABSTRACT FROM AUTHOR]

We describe primers and polymerase chain reaction (PCR) conditions to amplify 18 tetranucleotide microsatellite DNA loci in eastern bluebirds ( Sialia sialis). The primers were tested using individuals from two study sites in Georgia and South Carolina. Among individuals from the Georgia population ( n = 23), the primer pairs developed in this study yielded an average of 6.6 alleles per locus (range 2–12), an average observed heterozygosity of 0.56 (range 0.24–0.96) and an average polymorphic information content of 0.65 (range 0.3–0.86). Among individuals from the South Carolina population ( n = 19), the primer pairs yielded an average of 5.8 alleles per locus (range 2–9), an average observed heterozygosity of 0.56 (range 0.05–0.86) and an average polymorphic information content of 0.63 (range 0.29–0.83). [ABSTRACT FROM AUTHOR]

An alternative to classic sexual selection hypotheses for sex differentiated pre-mating behavior is that time available for mating--as individuals experience it--along with fitness differences among alternative potential mates, induces choosy versus indiscriminate mating behavior. This alternative hypothesis says that selection has acted so that all individuals flexibly express fitness-enhancing choosy, indiscriminate, and competitive mating behavior, induced by time-varying life histories, environmental and social cues. Key predictions of DYNAMATE, the formal model of adaptively flexible sex role behavior of individuals of both sexes within dynamically changing populations, include: (1) All individuals regardless of sex assess likely fitness outcomes from mating with alternative potential mates before expressing choosy or indiscriminate behavior. (2) Males and females express adaptively flexible, choosy and indiscriminate behavior so that individuals may change their behavior--from moment to moment--to fit dynamically changing circumstances. (3) Indiscriminate behavior of males and (4) choosy behavior of females would often be maladaptive even in species with greater female than male parental investment, when females have longer latencies to receptivity to re-mating than males, and when the relative reproductive rate of males is greater than in females. (5) Whether or not females show choosy behavior will not affect whether or not males exhibit choosy or indiscriminate behavior, and vice versa. (6) When other model parameters are equal, the proportion of individuals of a given sex expressing choosy or indiscriminate mating behavior is a function of the distribution of fitness ratios (a distribution of all fitness differences that would be conferred on an individual by mating with any two sequentially or simultaneously encountered alternative potential mates). (7) Whether same-sex individuals behaviorally compete is a function of the fitness that would be conferred if the strategist won access to a potential mate, but not a function of relative reproductive rate or its proxy, the operational sex ratio. We call for re-evaluation of sex differences in choosy, indiscriminate, and competitive behavior under strong experimental controls that level the ecological playing fields of males and females, i.e., under experimental conditions informing the mechanisms of phenotypic expression. We end with comments on the classic question of questions: why are the sexes as they are? [ABSTRACT FROM AUTHOR]

The classic view of choosy, passive females and indiscriminate, competitive males gained theoretical foundations with parental investment theory. When females invest more in offspring than males, parental investment theory says that selection operates so that females discriminate among males for mates (i.e., females are choosy and passive) and males are indiscriminate (i.e., males are profligate and competitive). Here we report tests of predictions using Drosophila pseudoobscura and D. melanogaster, with typical asymmetry in gamete sizes (females > males), and in D. hydei with far less asymmetry in gamete size. Experimental observations revealed that the labels "choosy, passive females" and "profligate, indiscriminate males" did not capture the variation within and between species in premating behavior. In each of the species some females were as active in approaching males (or more so) than males in approaching females, and some males were as discriminating (or more so) than females. In pairs focal males and females responded differently to opposite-sex than to same-sex conspecifics. Drosophila hydei were less sex-role stereotyped than the other two species consistent with parental investment theory. However, D. pseudoobscura females approached males more often than did D. melanogaster females, and male D. hydei approached females as often as males of the other two species, both results inconsistent with parental investment theory. Male D. pseudoobscura and D. hydei were more likely to approach males in same-sex pairs than male D. melanogaster, inconsistent with parental investment theory. [ABSTRACT FROM AUTHOR]

Focuses on the impact of feminism on evolutionary biology. Description of parental investment theory; Experiments on mating variance with the fly Drosophila melanogaster; Other theories on mating variance between the sexes.

Presents a study that examined the mutual interest between the sexes and reproductive success in Drosophila pseudoobscura. Materials and methods; Results; Discussion.

Presents an examination of aggressive and forced copulation in birds, highlighting the CODE hypothesis and social monogamy. Reasons for rarity of forced copulation in birds; Basis of the CODE hypothesis; Examination of sexual dialectic theory (SDT); Predictions of SDT; Analysis of the immediate fertilization enhancement hypothesis.

Tests the local resource competition (LRC) hypothesis which predicts that passerines will have daughter-biased sex ratios and anseriforms will have son-biased sex ratios. Observations of between-order variation in progeny sex ratios; Variation across latitude and within season; Selection through LRC arising in association with variation in relative son and daughter philopatry.

Presents information on experiments carried out regarding sex ratios. Proposal made by Trivers and Willard (1973); Who performed the first field test of the hypothesis concerning Trivers and Willard; Reference to the analysis of data.

We isolated and characterized 10 polymorphic microsatellite loci in Drosophila hydei. The number of alleles per locus ranged from 3 to 8 ( N = 23 individuals). Polymorphic information content ranged from 0.316 to 0.750 and observed heterozygosity from 0.261 to 0.913. These markers will be valuable in studies of sexual selection and parental investment in D. hydei. [ABSTRACT FROM AUTHOR]

Presents a study that observed adult eastern bluebirds placing fecal sacs on electric wires near Athens, Georgia. Methodology; Statistical analyses; Results of the study.

A quantitative theory of reproductive decisions (Gowaty & Hubbell 2009) says that individuals use updated priors from constantly changing demographic circumstances to predict their futures to adjust actions flexibly and adaptively. Our ecological/evolutionary models of ultimate causes seem consistent with Clark's ideas and thus suggest an opportunity for a unified proximate and ultimate theory of Bayesian animal brains, senses, and actions. [ABSTRACT FROM AUTHOR]

The article comments on the paper "Intrasexual Competition Among Females: Evidence for Sexual Selection?," by Rosvall, publisher in previous issue. The paper highlighted hypotheses on natural and sexual selection among females. However, the author argues that Rosvall missed other predictive hypotheses on among-female reproductive competition. She describes the syllogisms that constitute hypotheses of among-female selection.

The article focuses on the study by Clutton-Brook and Isvaran on sex differences in ageing in natural populations of mammals and birds. The study asserts that sex differences in animals are similar to humans due to the costs of male-male competition over mating and contests over defense of resources. It also introduces a new metric to the study of the cost of reproduction and fitness variances. However, it is criticized because the study used polygynous species which are mostly mammals.

Provides background and analysis on a study which observes the adaptive sex ratios among eggs of Seychelles warblers, Acrocephalus sechellensis. The implications for R.A. Fisher's equilibrium sex-ratio theory; The effects on the availability of food; The several important questions raised by the study; The paper by Komdeur and colleagues in the February 6, 1997 issue of `Nature.'