Intrasexual copulation and mate discrimination in a population of Nodilittorina radiata (Gastropoda: Littorinidae)

Intrasexual copulation and mate discrimination by Nodilittorina radiata (Gastropoda: Littorinidae) were studied on a concrete breakwater at Hakodate Bay, southern Hokkaido, Japan. Intrasexual (male–male) copulations were observed in 4.7–21.1% of copulating pairs on the shore. As females were relatively larger than males and males copulated with females larger than themselves, we hypothesized that males choose potential mates larger than themselves. However, two male mates showed no significant size preference in intrasexual copulations, suggesting that males do not choose relatively larger individuals as mates. In a laboratory mate-choice experiment, male N. radiata preferred to mate with females, indicating precopulatory sex identification. They copulated with males, however, at the frequency of 37%, perhaps because of sex misidentification.     

Female Copulation Calls in Guinea Baboons: Evidence for Postcopulatory Female Choice?

We tested the hypothesis that primate female copulation calls are a form of postcopulatory female choice. We collected data on female sexual swellings, sexual and agonistic behavior, copulation calls and postcopulatory behavioral interactions in a multimale-multifemale captive group of Guinea baboons over a 3-mo period. Males copulated with only a few females, and females copulated with only 1 or 2 different males in the group, suggesting a harem-like mating system similar to that of hamadryas and gelada baboons. Female copulations were most likely to occur at peak sexual swellings and male copulatory success was accounted for by dominance rank and age. Variation in female tendencies to call after copulation is best explained by the copulatory success of the male with which each female copulated the most and by the number of copulating partners. The findings are consistent with predictions that calls are likely to be associated with copulation with preferred males and the risk of sperm competition. The prediction that copulation calls increased the probability of postcopulatory mate guarding is also supported. Taken together, the findings suggest that female copulation calls may play an important role in postcopulatory sexual selection and in particular in the expression of postcopulatory female choice in primate species in which females have little opportunity to choose their mates or female mate choice is costly or both.     

Mating behavior of ring-tailed lemurs (Lemur catta) at Berenty,Madagascar

The mating behavior of ring-tailed lemurs at Berenty, Madagascar, was observed in April 1982. Although Troop A included five adult females, only two were observed to mate. The mating period covered two consecutive days, April 24 and 25. Each female was receptive for about 4 hr. Data from 47 copulations, of which 38 were with ejaculation, suggest that to be the first mating partner is of importance for male ring-tailed lemurs. Previously it has been suggested that male dominance is of little significance in determining mating partners. In this investigation it was observed that the second most dominant male MK was always the first mating partner. Only after several ejaculations and resultant fatigue did he lose possession of the female to lower ranking males, and the first ranking male was not seen to copulate with either female at any time. These results suggest that a male's mating success is partly, but not completely correlated with his dominance rank, and that other factors, including his length of residence in the group and female choice, also determine patterns of mating.     

Male Mate Choice in Trichogramma Turkestanica

In most animals it is the sex that invests the most in reproduction, generally the female, that expresses mate choice. However, in numerous species, males or both males and females are choosy. We investigated mate choice in males of the egg parasitoid Trichogramma turkestanica Meyer (Hymenoptera: Trichogrammatidae). We tested the impact of age and feeding status of males on their capacity to choose between virgin or mated and kin or non-kin females. As expected, males showed no preference between kin and non-kin mates, but inseminated virgin females over mated ones. No effect of age on the level of choosiness was found, but unfed males were choosier than fed ones. This is the first study to show an effect of feeding status of males on mate choice in insect parasitoids.     

MALE DOMINANCE, FEMALE MATE CHOICE, AND INTERSEXUAL CONFLICT IN THE ROSE BITTERLING (RHODEUS OCELLATUS)

An intersexual conflict arises when males and females differ in their reproductive interests. Although experimental studies have shown that females often mate with dominant males, it may not always be in the interest of a female to do so. Here we investigated the impact of male dominance on female mate choice and offspring growth and survival in the rose bitterling ( Rhodeus ocellatus ), a freshwater fish with a resource-based mating system. Three experimental mating trials were conducted using males of known dominance rank, but with different levels of constraint on male behavior. Thus, females were able to choose among; (1) males that were isolated from each other; (2) males that could see and smell each other, but could not directly interact; (3) males that could interact fully. Using a combination of behavioral observation and parentage analyses it was shown that female preferences did not correspond with male dominance and that male aggression and dominance constrained female mate choice, resulting in a potential intersexual conflict. The survival of offspring to independence was significantly correlated with female mate preferences, but not with male dominance. A lack of strong congruence in female preference for males suggested a role for parental haplotype compatibility in mate choice.     

Male Dominance Rank,Female Mate Choice and Male Mating and Reproductive Success in Captive Chimpanzees

Mating and consequently reproductive success in male vertebrates are predominantly determined by intermale competition and female mate choice. Their relative importance however, is still poorly understood. We investigated the interrelationship between male dominance rank — a formal indicator of male competitive ability — female mate choice, and male mating success in a multimale-multifemale group of captive chimpanzees. In addition, we examined the relationship between male dominance rank and reproductive success determined by genetic paternity analysis over a 13-yr period in the same captive population. We related the frequencies of sociosexual behaviors to the female anogenital swelling stage and female fertile phase as determined by urinary and fecal progestogen analysis. Rates of behaviors in both sexes increased with increasing intensity of female swelling, but they were not influenced by the timing of the fertile phase. Male mating success was clearly related to male dominance rank, with high-ranking males performing the overwhelming majority of copulations. This was mainly due to both rank-related rates of male soliciting behavior and intermale aggressiveness during the period of well-developed female anogenital swelling. Although females solicited copulations mainly from the high-ranking males and thus expressed a mate choice based on rank, their overall contribution in initiating copulations and thus influencing male mating success was low. The data on paternity from the population, which always contained 4 adult males, revealed that -males sired the majority (65%) of offspring. We conclude, that male dominance rank is an important determinant of male mating and reproductive success in captive (and presumably wild) chimpanzees and that female mate choice is of minor importance in modulating male reproductive outcome.     

Female Preferences Based on Male Quality in House Mice: Interaction between Male Dominance Rank and t-Complex Genotype

Considerable evidence indicates that female house mice (Mus domesticus) prefer dominant over subordinate males as mates. In addition, male genotype at the t-complex seems to be an important characteristic used by females in mate choice. Specifically, female mice that carry a t-haplotype at the t-complex prefer +/+ over +/t males as mates. The purpose of the present study was to examine the relative contributions of male dominance rank and male t-complex genotype to female mating preference when both factors were systematically varied. We tested females of three genotypes (+/+, +/t, and t/t) in a preference apparatus using pairs of stimulus males varying in relative dominance status and t-complex genotype. In general, when given the choice, females preferred dominant over subordinate males regardless of the male's t-complex genotype. The preference for dominant males was manifested when both stimulus males were of the same t-complex genotype but differed in dominance rank. In addition, when forced to choose between a dominant +/+ and subordinate +/t or between a dominant +/t and subordinate +/+, females continued to prefer the dominant male. Preference for dominant males was independent of female genotype. Only when both males were dominant but differed in t-complex genotype (i.e. one male was +/+ and the other +/t) or when males were unranked (i.e. had not been used in aggressive encounters to determine dominance rank) did females carrying t-haplotypes manifest preferences for +/+ males. Quite unexpectedly, when both males were subordinate but differed in t-complex genotype, preferences of all females shifted in the direction of the +/t male. It is not clear from present data whether the propensity of females to give greater weight to male dominance rank than to t-complex genotype in choosing mates results in greater fitness. However, if these trends are found in natural populations, it would indicate that the role of mating preference in regulating the frequency of t-haplotypes in wild populations is less straightforward than had been previously thought.     

Male age and sexual experience affect male mating behavior in the hawthorn spider mite,Amphitetranychus viennensis

As is reported, in species with first-male sperm precedence, male age and previous sexual experience play crucial roles in male mating behavior. In the hawthorn spider mite, Amphitetranychus viennensis Zacher, previous studies showed that only females that copulated for the first time could achieve fertilization. Based on this, the effects of male age and mating history on male mate choice and male mate competition were investigated. It was confirmed that males could distinguish virgins from fertilized females but they were unable to discriminate between virgins and unfertilized females. Interestingly, the copulation duration of males mated with fertilized females was much shorter than that of males mated with virgins or unfertilized females. Additionally, for male mating choice, males of all ages and more experienced males preferred 5-day-old virgin females, whereas only less experienced males preferred 1-day-old virgin females. In male-male competition, 3-day-old males were more competitive and obtained more copulations compared with others. Copula duration was closely related to male age. Though no significant differences were observed in mating competition between virgin and mated males, copula duration of males in first copulation was the longest and gradually shortened in subsequent copulations. In all, this investigation demonstrated that male age and sexual experience affected male mate choice and male-male competition, leading to further insight into the influences of male age and sexual experience on the reproductive fitness of both sexes.

     

Mate choice promotes inbreeding avoidance in the two-spotted spider mite

Since inbreeding in Tetranychus urticae can reduce offspring fitness, sexual selection may favour disassortative mate choice with respect to relatedness of the mating partners. We tested whether T. urticae shows this preference for mating with unrelated partners. We chose an experimental set-up with high potential for female choosiness, since females only mate once and are therefore expected to be the choosier gender. An adult virgin female was placed together with two adult males from the same population. One male was unrelated and the other male was related—a brother with whom she had grown up. Significantly more copulations (64%) took place with the unrelated male. Time to mating did not depend on the female-to-male relatedness. The remaining (non-copulating) male tried to interfere with the ongoing mating in the majority of cases, but this interference did not depend on the female-to-male relatedness. These results imply that T. urticae (a) can recognize kin (via genetic and/or environmental similarity) and (b) has the potential to avoid inbreeding through mate choice.     

Female mate choice in vervet monkeys (Cercopithecus aethiops sabaeus)

Female mate choice was examined in a captive group of vervet monkeys (Cercopithecus aethiops sabaeus). Male-female interactions were examined under both dyadic and group conditions to determine whether females mate with different males under the two conditions. Results showed that all females preferred to mate with the alpha male under both dyadic and group conditions. Alpha females, however, were more successful than subordinate females in rejecting the sexual solicitations of subordinate males. Thus female dominance status played an important role in determining the degree to which females exercised mate choice.     

The Disruption Hypothesis Does Not Explain Mate‐Choice Copying in the Guppy (Poecilia reticulata)

In some species, female mate choice is non‐independent as, under certain circumstances, females may copy the mate choice of other nearby females. One standard experimental protocol used to test for mate‐choice copying is the mate‐choice ‘reversal’ protocol. In this protocol, a focal female is allowed to choose between two males as potential mates and then is presented with an opportunity to see another female (i.e. the model female) choose the male that she did not initially choose. The focal is subsequently allowed to again choose between the same set of males. An observed reversal of her initial choice in this second preference test has been previously interpreted as evidence for mate‐choice copying. Alternatively, it has recently been proposed that environmental events, such as seeing the mate choice of nearby females that occur within the visual field of a female actively engaged in mate assessment, may ‘disrupt’ her decision‐making behavior and consequently alter the consistency of her mating preference, and may thus cause mate‐choice reversals. The disruption hypothesis predicts that if a model female is placed near the male that the focal female initially chose, the latter's mate preference would be disrupted and she would subsequently and consistently prefer the male that she initially rejected. Here we examined whether the disruption hypothesis explains mate‐choice copying in the guppy (Poecilia reticulata). Our results do not support this hypothesis, but rather provide further support for mate‐choice copying in the guppy.     

Mate Choice Copying in Female Humpback Limia (Limia nigrofasciata, Family Poeciliidae)

Mate choice copying is a mechanism of non‐independent mate choice that has important implications for models of evolution and sexual selection. In this study, we examined copying behavior in female humpback limia (Limia nigrofasciata). In three experiments, we allowed a focal female to choose between two males on opposite sides of an aquarium, then repeated the choice trial with the following modifications: (i) with no model female, (ii) with a model female added adjacent to the initially non‐preferred male, or (iii) with the model female adjacent to the initially preferred male. In the absence of other females, focal females displayed consistent mate preferences, measured as a significantly higher amount of time spent near the preferred male in both parts of the trial. When a model female was added adjacent to the initially non‐preferred male, focal females spent significantly more time near that male than they had in the first part of the trial, and significantly less time near the male they had initially preferred. When we placed the model female next to an initially preferred male as a control, the time spent by the focal female with the initially preferred or initially non‐preferred male did not change significantly. We conclude that female mate choice copying may be important in humpback limia, causing focal females to spend more time in preference zones of males they had not at first preferred.     

Bias in the heritability of preference and its potential impact on the evolution of mate choice

The evolution of mate choice is a function of the heritability of preference. Estimation in the laboratory is typically made by presenting a female with a limited number of males. We show that such an approach produces a downwardly biased estimate, which we term the heritability of choice. When preference is treated as a threshold trait then less biased estimates are obtained particularly for preferences based on the relative value of the preferred trait. Because females in the wild typically survey on average less than five males we argue that the heritability of choice may be more meaningful than the heritability of preference. The restricted number of males surveyed can lead to a reduction in the phenotypic variance of the preferred trait in the group of males selected by the females if the phenotypic variance in preference is equal to or less than the phenotypic variance in the referred trait. If the phenotypic variance in preference exceeds that of the preferred trait then the opposite occurs. A second effect of the restricted number of males sampled is that females are likely to mate initially with males that are not the most preferred. The failure to find the most preferred male may account for the common observation of multiple matings and extra-pair copulations. We suggest that current explanations for polyandry need to take this failure into account.     

Do male house mice (Mus musculus) discriminate between females that differ in nutritional status?

Most studies of mate choice have focused on female preference for male traits because it is generally assumed that since males provide less parental investment they are not choosy. However, if males suffer missed opportunity costs by mating with lower quality females, selection should favor males with the ability to discriminate among females. We tested the hypothesis that male house mice (Mus musculus) discriminate between females that differ in nutritional status (non-food-deprived versus food-deprived). We recorded the time males spent investigating either type of female and used that to determine preference (spending ≥55% of their total investigation time with one female). We also examined the effects of female nutritional status and female preference status (preferred versus non-preferred) on the reproductive success of males. Males did not display a preference for non-food-deprived females nor did their reproductive success vary with nutritional status or preference status of females. Interestingly, males spent more time investigating females that were closest to the male's own weight. In addition, pairs that were closer in weight were more likely to produce a litter. These results suggest that male house mice are capable of discriminating among females and that such discrimination may influence their reproductive success.     

Sexual Selection in Insect Choruses: Influences of Call Power and Relative Timing

Female preference for male song in acoustic insects is primarily influenced by call energy or power, but nonenergy features such as the relative timing of male calls may also be critical in preference. Preferences for leading calls, which may be a type of precedence effect, are an example of the latter factor. In various species, females preferentially orient toward the leading of two or more spatially separated calls presented in controlled playback experiments, however the importance of this effect on mate choice in actual choruses and natural populations is generally unknown. We studied the determinants of mate choice in reenacted choruses of the tettigoniid Ephippiger ephippiger, a species in which females prefer leading calls in two-choice experiments, and neighboring males adjust their relative call timing in a way that reduces the incidence of following calls. We found that mate choice, as indicated by the pattern of female settlement, largely reflects call rate and call constancy. But, we also found suggestions that female choice is influenced by the acoustic neighborhood in which a male sings, males in neighborhoods with more overall singing being preferred, and by a males incidence of leading calls relative to his neighbors. Although statistically inconclusive owing to few relevant samples, we note that the level of preference for leading calls observed in E. ephippiger choruses is comparable to that found in controlled playback experiments.     

Male Mate Choice in Lemur catta

Though females are generally more selective in mate choice, males may also derive reproductive benefits from exercising mate selectivity if one or more factors limit male reproductive success and females differ in reproductive potential. I used male mating effort as a proxy for male mate choice in ring-tailed lemurs (Lemur catta). I calculated mating effort as the rate of male-male agonism during each female's estrous period 30 min before and 30 min after the first and last mountings with intromission. I collected data on 1 free-ranging Lemur catta troop during 2 consecutive breeding seasons on St. Catherines Island, USA. In both yrs, male mating effort differed significantly among troop females once I adjusted male-male agonistic rates to reflect agonistic intensity, and I corrected for the number of observed mates per female (2000: χ² = 27.43, df = 3, p < 0.0001; 2001: χ² = 21.10, df = 3, p < 0.001). Results strongly suggest male mate choice. Contrary to expectation, males did not expend the greatest mating effort for females with the highest dominance status nor the highest reproductive success. Males preferred females that either: (1) belonged to the age class in which fecundity and infant survival is the highest at this site (4–9 yrs), or 2) were older females (≥10 yrs) with high reproductive success. Female reproductive potential appears to be an important variable determining male mating effort in Lemur catta.     

Time spent close to a sexual partner as a measure of female mate preference in a sex-role-reversed population of the blenny<Emphasis Type="Italic"> Salaria pavo</Emphasis> (Risso) (Pisces: Blenniidae)

In most species females do not exhibit conspicuous sexual behaviours and female mate preferences are often measured by means of the time spent close to males. In spite of its widespread use, in only a few studies has this measure been validated as a reliable indicator of female mate preference. Sex-role-reversed species offer a better opportunity to test female preferences, as females usually court males. We tested in a sex-role-reversed population of the blenny Salaria pavo (Risso) if the time spent by females close to males related to the number of courtship displays directed towards males, and whether these measures of female preference reliably predicted matings. Females were simultaneously presented with two males behind a glass partition and the time spent close to each male was measured. We then allowed females to have access to the males' compartments and measured the courtship behaviours performed by females towards each male and recorded with which of the males females spawned. Females spent more time close to the male that subsequently received more courtship displays, and the preferred male had a more developed head crest. However, both measures of female preference failed to predict matings. Females were often attacked by males and probably had, in some occasions, to spawn with the less preferred male. Females that spawned with the previously preferred male had more swollen bellies than females that spawned with the less preferred male, suggesting a male preference towards more ripe females. These results validate the use of "time spent close to a sexual partner" as a measure of female preference in S. pavo. We argue that matings may not always reliably indicate mate preferences, particularly in the less choosy sex.Communicated by R. Serrão Santos     

Paternity Determination in Two Groups of Eulemur fulvus mayottensis: Implications for Understanding Mating Strategies

We used random amplified polymorphic DNA (RAPD) to determine paternity in two groups of brown lemurs (Eulemur fulvus mayottensis). We analyzed the results in relation to behavioral data on observed copulations, dominance relationships among adult males, and female behavior. The association between paternity determination and behavioral sampling shows that paternity determination is a crucial tool for understanding the mating strategies and reproductive success in the studied species. In brown lemurs, dominance relationships between males are correlated with reproductive success, but male social dominance could be altered by female choice as suggested by the ability of subordinate males to sire offspring in the presence of a dominant male.     

The influence of a male's dominance status on female choice in Syrian hamsters

This study evaluated the importance of dominance status on mate selection in Syrian hamsters. In one experiment, sexually receptive females were allowed to choose between tethered males which differed in status. The choice was consistently in favor of the dominant male. The female spent more time in lordosis in the presence of the dominant male. The dominant also obtained a significantly greater number of intromissions. A second experiment investigated whether prior familiarization was essential to permit a female to express mating preferences in a situation where she was free to interact with three males. Again, the dominants were most often preferred and obtained greater sexual access to the female. Prior familiarization or extensive contact with the males was not necessary to support the female's selection of the dominant as a mating partner. The choice occurred quickly, generally within 5 min after contacting the males. Although females did mate with the subordinates, this typically occurred late in the tests. The significance of these data with respect to mate choice and probable paternity effects are discussed.     

Context‐ and State‐Dependent Male Mate Choice in a Sexually Cannibalistic Spider

High male mating investment may favor selection on male mate choice particularly if females vary in quality. Terminal investment strategies constitute a maximal mating effort and have evolved independently in the absence of paternal investment in several spider taxa including the genus Argiope. To test for male mate preferences in the above context, we used the sexually cannibalistic spider A. bruennichi. We varied male state (mating status and post‐maturation age) as well as the competitive context and quantified male mate choice decisions between females of different states and developmental stages in binary choice tests. We found an overall adaptive preference for the virgin against the mated female regardless of male mating state. Furthermore, we demonstrated that older males paid more attention to female fecundity‐related traits than to mating status. In a second set of experiments, we offered males a choice between a virgin and a subadult female and varied the competitive context which had no effect on male decisions. Curiously, a preference for the virgin adult female was only apparent after exclusion of females that matured <3 d prior to the test. Repeated tests of males supported the hypothesis that males do not distinguish between a freshly matured virgin female and a subadult female. Our results show that male spiders execute mate choice based on information collected from female silk strands and that they integrate their own state into mating decisions.