Changes in courtship behaviour following rejection: The influence of female phenotype in Drosophila melanogaster

Courtship can be costly and so selection should favour individual males that reduce courtship towards female types that have a low probability of resulting in copulation. One way males can do this is by associating previous courtship failure with the traits of particular rejecting females. We characterised changes in male Drosophila melanogaster courtship behaviour following a failed mating attempt with one of the four female phenotypes that varied in size, age or mating status. To do this, we assessed individual courtship behaviour for each male presented again with a female of the same phenotype that previously rejected him. Males reduced subsequent courtship most strongly for recently mated (sexually non‐receptive) females. More interestingly, males also significantly reduced courtship activity following a failed mating experience from old females but did not do so for control (large, young, virgin) or small females. As such, males significantly reduced courtship towards both female types possessing chemical cues associated with their phenotype (age and mating status), but not towards a female phenotype based on physical characteristics (body size). Our results suggest that males are able to modify their courtship behaviour following experience, but that they are better prepared to associate chemical traits that may be more reliable indicators of the likelihood of courtship failure.     

Sociality, Mate Choice, and Timing of Mating in American Bison (Bison bison): Effects of Large Males

We studied group size, composition, and mating activities in American bison (Bison bison) during rut on the Delta Junction Bison Range in interior Alaska, USA, in 1996 and 1997. Our purpose was to determine the effects of large males (≥5 yr old) on mating and associated activities. Groups with large males were larger than those containing smaller males. Most groups of bison were mixed‐sex (90%), but large males occurred in only one‐half of all groups. Moreover, females in groups with large males were more likely to copulate than those in groups with smaller males, indicating a female preference for large males. Nevertheless, our results are consistent with large males seeking out adult females for mating rather than vice versa. Mating peaked in mid‐August during both the study years and was highly synchronous. Scent marking was coincident with mating, an outcome consistent with a hypothesis of such behavior triggering ovulation. Scent marking by large male bison occurred in both male–male and male–female contexts, but was associated most often with sexual activities. No differences in group size occurred with changes in weather or among vegetation types occupied by bison. Group size of bison, however, was larger with increasing distance from the forest edge, which likely was a response to predation risk in this predator‐rich environment.     

Male Condition, Female Choice, and Extreme Variation in Repeated Mating in a Scaly Cricket, Ornebius aperta (Orthoptera: Gryllidae: Mogoplistinae)

Mating in the scaly cricket Ornebius aperta often includes the transfer of many spermatophores to individual females during extended copulatory interactions. We manipulated male condition in staged matings to determine whether this could explain variation in the number of repeated copulations seen across pairs. Males on a high nutrient diet were in good condition, were more likely to mate repeatedly, and transferred more spermatophores on average than low-diet males (in poor condition). High-diet males were more likely to produce a vibratory signal that increased female receptivity to repeated mating attempts. Courtship and copulatory interactions were always terminated by females, and in every case males had already formed a spermatophore when deserted by females. We conclude that variation in male repeated mating success may be due to female choice rather than an inability or unwillingness of low-diet males to produce spermatophores.     

FEMALES RECEIVE A LIFE-SPAN BENEFIT FROM MALE EJACULATES IN A FIELD CRICKET

Abstract.— Mating has been found to be costly for females of some species because of toxic products that males transfer to females in their seminal fluid. Such mating costs seem paradoxical, particularly for species in which females mate more frequently than is necessary to fertilize their eggs. Indeed, some studies suggest that females may benefit from mating more frequently. The effect of male ejaculates on female life span and lifetime fecundity was experimentally tested in the variable field cricket, Gryllus lineaticeps. In field crickets, females will mate repeatedly with a given male and mate with multiple males. Females that were experimentally mated either repeatedly or multiply lived more than 32% longer than singly mated females. In addition, multiply mated females produced 98% more eggs than singly mated females. Because females received only sperm and seminal fluid from males in the experimental matings, these life‐span and fecundity benefits may result from beneficial seminal fluid products that males transfer to females during mating. Mating benefits rather than mating costs may be common in many animals, particularly in species where female mate choice has a larger effect on male reproductive success than does the outcome of sperm competition.     

SEXUAL SELECTION ON BODY SIZE AND SHAPE IN THE WESTERN HARVESTER ANT,POGONOMYRMEX OCCIDENTALIS CRESSON

Mating in social insects has generally been studied in relation to reproductive allocation and relatedness. Despite the tremendous morphological diversity in social insects, little is known about how individual morphology affects mating success. We examined the correlation of male size and shape with mating success in the western harvester ant, Pogonomyrmex occidentalis. Larger males had significantly higher mating success in two independent collections of males at mating aggregations. We also detected significant linear and nonlinear selection on aspects of male shape that were consistent across years. These shape components are independent of size, suggesting that male mating success is a complex function of size and shape. Successful males had elongate thoraxes and short mandibles relative to males collected at random at the lek. Overall, mated males also had longer postpetioles relative to body size, but there was also evidence of nonlinear selection on relative postpetiole length in both years. We found no evidence of assortative mating based on size or multivariate shape measures in either year, but in one year we found weak assortative mating based on some univariate traits.     

Dietary choices are influenced by genotype,mating status,and sex in Drosophila melanogaster

Mating causes many changes in physiology, behavior, and gene expression in a wide range of organisms. These changes are predicted to be sex specific, influenced by the divergent reproductive roles of the sexes. In female insects, mating is associated with an increase in egg production which requires high levels of nutritional input with direct consequences for the physiological needs of individual females. Consequently, females alter their nutritional acquisition in line with the physiological demands imposed by mating. Although much is known about the female mating‐induced nutritional response, far less is known about changes in males. In addition, it is unknown whether variation between genotypes translates into variation in dietary behavioral responses. Here we examine mating‐induced shifts in male and female dietary preferences across genotypes of Drosophila melanogaster. We find sex‐ and genotype‐specific effects on both the quantity and quality of the chosen diet. These results contribute to our understanding of sex‐specific metabolism and reveal genotypic variation that influences responses to physiological demands.     

Effect of age on reproductive attributes of an aphidophagous ladybird, Cheilomenes sexmaculata

The effect of both male and female age was investigated on certain reproductive attributes, viz. mating incidence, mating duration, fecundity, percent egg viability, ratio of reproductive and non‐reproductive periods and reproductive rate, of an aphidophagous ladybird, Cheilomenes sexmaculata (Fabricius). Females started mating at the age of 8 hours post‐emergence (PE) and males at the age of 2 days PE. Mating in the laboratory was a male‐dominated phenomenon. The mating duration and reproductive rate of 10‐day‐old females when mated with males of varying ages increased up to the male age of 60 days, and thereafter decreased, whereas, fecundity, egg viability and ratio of reproductive and non‐reproductive periods increased up to the male age of 50 days, and thereafter declined. However, when females of varying ages were mated with 10‐day‐old males, fecundity and reproductive rate increased up to 40 days of female age, respectively, then decreased. The ratio of reproductive and non‐reproductive periods increased with increasing age of females. Mating age for optimal reproductive output was 10J50‐day‐old males and NE to 40‐day‐old females. Reproductive cessation in males was recorded after 50 days PE, whereas in females at the age of 40 days PE. Higher mating durations lead to elevated reproductive rates. Delay in the reproductive phase was positively correlated with longevity. The results of this study may aid mass multiplication of this ladybird by identifying and promoting usage of adults of optimal age. Our results also enhance our understanding of the effect of age on reproductive attributes in ladybirds.     

Effects of multiple matings on reproductive fitness of male and female Diaeretiella rapae

Mating frequency and the amount of sperm transferred during mating have important consequences on progeny sex ratio and fitness of haplodiploid insects. Production of female offspring may be limited by the availability of sperm for fertilizing eggs. This study examined multiple mating and its effect on fitness of the cabbage aphid parasitoid Diaeretiella rapae McIntosh (Hymenoptera: Aphidiidae). Female D. rapae mated once, whereas males mated with on average more than three females in a single day. The minimum time lag between two consecutive matings by a male was 3 min, and the maximum number of matings a male achieved in a day was eight. Sperm depletion occurred as a consequence of multiple mating in D. rapae. The number of daughters produced by females that mated with multiple‐mated males was negatively correlated with the number of matings achieved by these males. Similarly, the proportion of female progeny decreased in females that mated with males that had already mated three times. Although the proportion of female progeny resulting from multiple mating decreased, the decrease was quicker when the mating occurred on the same day than when the matings occurred once per day over several days. Mating success of males initially increased after the first mating, but then males became ‘exhausted’ in later matings; their mating success decreased with the number of prior matings. The fertility of females was affected by mating with multiple‐mated males. The study suggests that male mating history affects the fitness of male and female D. rapae.     

Is bigger better? Male body size affects wing‐borne courtship signals and mating success in the olive fruit fly,Bactrocera oleae (Diptera: Tephritidae)

Variations in male body size are known to affect inter‐ and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor affecting signal strength and mate choice. We evaluated the effect of male size on courtship displays and mating success of the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae). Wing vibrations performed during successful and unsuccessful courtships by large and small males were recorded by high‐speed videos and analyzed through frame‐by‐frame analysis. Mating success of large and small males was investigated. The effect of male–male competition on mating success was evaluated. Male body size affected both male courtship signals and mating outcomes. Successful males showed wing‐borne signals with high frequencies and short interpulse intervals. Wing vibrations displayed by successful large males during copulation attempt had higher frequencies over smaller males and unsuccessful large males. In no‐competition conditions, large males achieved higher mating success with respect to smaller ones. Allowing large and small males to compete for a female, large males achieve more mating success over smaller ones. Mate choice by females may be based on selection of the larger males, able to produce high‐frequency wing vibrations. Such traits may be indicative of “good genes,” which under sexual selection could means good social‐interaction genes, or a good competitive manipulator of conspecifics.     

Variation in the benefits of multiple mating on female fertility in wild stalk‐eyed flies

Polyandry, female mating with multiple males, is widespread across many taxa and almost ubiquitous in insects. This conflicts with the traditional idea that females are constrained by their comparatively large investment in each offspring, and so should only need to mate once or a few times. Females may need to mate multiply to gain sufficient sperm supplies to maintain their fertility, especially in species in which male promiscuity results in division of their ejaculate among many females. Here, we take a novel approach, utilizing wild‐caught individuals to explore how natural variation among females and males influences fertility gains for females. We studied this in the Malaysian stalk‐eyed fly species Teleopsis dalmanni. After an additional mating, females benefit from greatly increased fertility (proportion fertile eggs). Gains from multiple mating are not uniform across females; they are greatest when females have high fecundity or low fertility. Fertility gains also vary spatially, as we find an additional strong effect of the stream from which females were collected. Responses were unaffected by male mating history (males kept with females or in male‐only groups). Recent male mating may be of lesser importance because males in many species, including T. dalmanni, partition their ejaculate to maintain their fertility over many matings. This study highlights the importance of complementing laboratory studies with data on wild‐caught populations, where there is considerable heterogeneity between individuals. Future research should focus on environmental, demographic and genetic factors that are likely to significantly influence variation in individual female fecundity and fertility.     

Mating behaviour of Dacus ciliatus (Loew) [Diptera:Tephritidae]: comparisons between a laboratory and a wild population

As part of the development of a sterile insect technique (SIT) application for the Ethiopian fruit fly, Dacus ciliatus, we studied the mating behaviour of a laboratory‐adapted strain (a 4‐year‐old colony kept for more than 40 generations) and a wild population. Effects of laboratory rearing and irradiation were assessed by carrying out mating compatibility and male mating competitiveness tests using a 1:1 ratio between irradiated (120 Gy) laboratory males and non‐irradiated wild males. Mating behaviour was studied on host and non‐host plants under field cage conditions. To assess the effect of mass rearing upon male performance, we repeated the mating competitiveness test using non‐irradiated laboratory insects. The findings indicated a high degree of compatibility among the two populations and satisfactory competitiveness of the irradiated laboratory males (ca. 35%). The competitiveness of non‐irradiated laboratory males was also ca. 35%, suggesting that no adverse effects resulted from their irradiation. Mating occurred only at twilight and mainly on the underside of leaves of non‐host plants (lemon trees). Findings are discussed in view of their implications for a future application of SIT against this fruit fly pest.     

Individual Variation in Male Size and Behavioral Repertoire in the Sailfin Molly Poecilia latipinna

Variation among individuals in the expression of behaviors and associations of behaviors in different contexts can lead to the maintenance of behavioral polymorphisms. Individual variation in morphology is often associated with behavioral polymorphism, yet the degree to which morphology predicts behavioral phenotype is not well understood. We measured individual variation in size and behaviors in the sailfin molly, Poecilia latipinna, by comparing the behavior of individual males of different sizes across four different contexts (mating, exploratory tendency, sociability, and predator inspection). We also investigated the degree to which male size, a fixed genetic trait, influenced the expression of each behavior and associations between behaviors. We found that male mollies show strong associations between certain behaviors and only some of these are predicted by male size. For example, size has a strong influence on the courtship‐boldness axis with larger males showing higher rates of courtship displays and being bolder in predator inspection. A positive association was found between exploratory tendency, sociability, and gonopodial thrusting rates, yet the expression of these behaviors was independent of male size. Thus, sailfin mollies, like many fish species, show associations of behaviors that contribute to differences among males in personality type. The fixed genetic effect of male size at maturity influences courtship and boldness, but individual variation in exploratory tendency, sociability, and sneak copulation attempts through gonopodial thrusts is independent of male size. Such variation among males in behavioral associations within and between different contexts may slow the rate at which populations of P. latipinna can diverge in individual behaviors.     

The unexpected mating system of the androdioecious barnacle Chelonibia testudinaria (Linnaeus 1758)

Androdioecy was first described by Darwin in his seminal work on barnacle diversity; he identified males and hermaphrodites in the same reproductive population. Today, we realize that many androdioecious plants and animals share astonishing similarities, particularly with regard to their evolutionary history and mating system. Notably, these species were ancestrally dioecious, and their mating system has the following characteristics: hermaphrodites self‐fertilize frequently, males are more successful in large mating groups, and males have a mating advantage. A male mating advantage makes androdioecy more likely to persist over evolutionary times. Androdioecious barnacles, however, appear to persist as an outlier with a different evolutionary trajectory: they originate from hermaphroditic species. Although sexual systems of androdioecious barnacles are known, no information on the mating system of androdioecious barnacles is available. This study assessed the mating system of the androdioecious barnacle Chelonibia testudinaria. In contrast to other androdioecious species, C. testudinaria does not self‐fertilize, males do not have a mating advantage over hermaphrodites, and the average mating group is quite small, averaging only three individuals. Mating success is increased by proximity to the mate and penis length. Taken together, the mating system of C. testudinaria is unusual in comparison with other androdioecious plants and animals, and the lack of a male mating advantage suggests that the mating system alone does not provide an explanation for the maintenance of androdioecy in this species. Instead, we propose that sex‐specific life history equalizes male and hermaphroditic overall fitness.     

Does Female Personality Determine Mate Choice Through Sexual Cannibalism?

Animal personalities (e.g. consistent across‐context behavioural differences between individuals) can lead to differences in mate choice. However, evidence for this link remains limited. Pre‐mating sexual cannibalism can be a behavioural syndrome (i.e. a suboptimal personality) in which adaptive female aggression towards heterospecific prey spills over on non‐adaptive aggression towards courting males, independently of the female mating or feeding status (i.e. the ‘aggressive spillover hypothesis’, ASH). On the other hand, sexual cannibalism can also be a form of mate choice by which females selectively kill or mate with males depending on the male phenotype. We introduce the hypothesis that the most aggressive females in the population will not only attack males more frequently, but will be less likely to impose sexual selection on males through sexual cannibalism. Assuming that in a field common garden experiment in which females were fed ad libitum the rate of weight gain by a female may reflect her voracity or aggressiveness, we show that in the cannibalistic burrowing wolf spider Lycosa hispanica (formerly L. tarantula), voracity towards heterospecific prey predicts a female's tendency towards sexual cannibalism. Unmated females with higher weight gains were more cannibalistic and attacked males regardless of the male phenotype. On the other hand, females that were less voracious tended to be less cannibalistic, and when they did kill a male, they were selective, killing males in poorer condition and mating with those in better condition. Our results demonstrate that females with different phenotypes (growth rates) differently imposed selection on male condition, tentatively supporting the hypothesis that female aggression levels can spill over on sexual selection through sexual cannibalism.     

Vibratory signals enhance mate-guarding in a water strider (Hemiptera: Gerridae)

Mating males of the water strider Gerris remigisproduce vibratory signals when-single males grasp mating pairs. When played through live females with dead males on their backs, these signals repelled mating attempts by single males. A previous study showed that male mate-guarding enhances female foraging effectiveness in this species. Thus male mate-guarding signals also enhance female foraging effectiveness.     

Sexual Competition,Coercive Mating and Mate Assessment in the One‐Sided Livebearer,Jenynsia multidentata: Are They Predictive of Sexual Dimorphism?

We investigated the mechanisms of sexual selection operating on body size in the one‐sided livebearer (Jenynsia multidentata), a small fish characterized by male dwarfism. Mating in the one‐sided livebearer is coercive: males approach females from behind and try to thrust their copulatory organ at the female genital pore. Females counter males' mating attempts by either swimming away or attacking them. We tested the hypothesis that the components of sexual selection favouring small size in males (sexual coercion) were more effective than those favouring a large size (male competition and mate choice). When alone, small males had a significantly higher success in their mating attempts than large males. The proportion of successful attempts was also positively correlated with female size. When two males competed for the same female, the large male had a significant mating advantage over the small one. With a 1 : 1 sex ratio, the large‐male mating advantage vanished because each male tended to follow a different female. Large males, however, preferentially defended large females, thus compelling small males to engage with smaller, less fecund females. Males did not discriminate between gravid and non‐gravid females, but preferred mating with larger females. This preference disappeared when males were much smaller than the female, probably in relation to the risk for the male of being eaten or injured by the female. In a choice chamber, male‐deprived females that had their sperm storage depleted remained close to males and showed a preference for large individuals, a behaviour not observed in non‐deprived females. Nonetheless, when placed with males in the same aquarium, all females showed avoidance and aggression. Struggling may represent a way by which the female assesses the skill and endurance of males.     

Mating Success in the Polyandrous Social Wasp Vespula maculifrons

The mating decisions made by social insect males and females profoundly affect the structure of colonies and populations. However, few studies have used experimental approaches to understand mating behavior and mate choice in social insect taxa. This study investigated mating success in the polyandrous social wasp Vespula maculifrons. Mating trials were designed to test predictions that characteristics of body size and colony‐of‐origin would affect mating success. We first investigated if size differences existed among individuals and found that males from different colonies differed significantly in the size of nine morphological traits. However, male trait size was not significantly associated with male mating success. In contrast, females from different colonies differed significantly in only six of the nine measured traits, and four of these traits were associated with successful mating behaviors. Specifically, the correlated traits of gaster length, third tergum length, antennal length, and total length were positively associated with female mating success. Thus, long females experience mating advantages over females that are short. We also found that males and females from one particular colony displayed significantly greater mating activity than individuals from other colonies. Thus, the colony from which individuals originate plays an important role in determining mating success. Finally, our experiments failed to detect any evidence of nestmate avoidance during the mating trials. Overall, our data suggest that social insect reproductives may experience differential mating success based on their phenotype or developmental environment.     

Male mating success and female mate choice in the river sculpin,Cottus nozawae (Cottidae)

Synopsis Mating success of males and its correlates were investigated in a natural population of the polygynous fluvial sculpinCottus nozawae. Furthermore, the female mate preference of this species was examined experimentally under alternative conditions for mating in a stream. The mating success of individual males (the number of females with which a male mated) ranged between 0 and 8 with a mean of 2.41 in 1983 and 2.52 in 1989, in a population of which the sex ratio was about 1 : 2 in both years, skewed toward females. Mainly due to the excess of nests without egg masses and the few nests with one egg mass, the distribution of male mating success did not fit a Poisson distribution, indicating its non-randomness. Male mating success was not correlated either with the size of the nest rocks or with the male size, suggesting that these two variables are not determinants of mating success. The mate choice experiments demonstrated that females of this species more frequently chose smaller males as mates whose nests already contained eggs than large males without eggs. Additionally, an analysis of stomach contents of guarding males suggested that the parental males ate their own eggs during egg guarding (filial-cannibalism). Based on these results and on a comparison of reproductive characteristics with congeneric species, it is suggested that one of the most important determinants for female mate choice inCottus species may be whether or not parental males are filial egg cannibals.     

Mating with large males decreases the immune defence of females in Drosophila melanogaster

Mating has been widely reported to be a costly event for females. Studies indicate that female cost of mating in terms of fecundity and survivorship can be affected by their mates, leading to antagonistic coevolution between the sexes. However, as of now, there is no evidence that the female cost of mating in terms of immune defence is affected by their mates. We assess the effect of different sized males on antibacterial immune defence and reproductive fitness of their mates. We used a large outbred population of Drososphila melanogaster as the host and Serratia marcescens as the pathogen. We generated three different male phenotypes: small, medium and large, by manipulating larval densities. Compared to females mating with small males, those mating with large males had higher bacterial loads and lower fecundity. There was no significant effect of male phenotype on the fraction of females mated or copulation duration (an indicator of ejaculate investment). Thus, our study is the first clear demonstration that male phenotype can affect the cost of mating to females in terms of their antibacterial immune defence. Mating with large males imposes an additional cost of mating to females in terms of reduced immune defence. The observed results are very likely due to qualitative/quantitative differences in the ejaculates of the three different types of males. If the phenotypic variation that we observed in males in our study is mirrored by genetic variation, then, it can potentially lead to antagonistic coevolution of the sexes over immune defence.     

Opposite Latitudinal Clines for First Mating and Second Mating (Remating) in Males of Drosophila melanogaster

Although female remating has been studied extensively in insects, few studies have been carried out for male remating (second mating). In this study, we analyzed Drosophila melanogaster males for their remating potential, using iso‐female line culture initiated with wild flies collected from eight Indian geographic localities. We examined the association of latitude and percent melanization with first and second male mating (including mating‐related traits). Our results indicated that second male mating has a negative latitudinal cline opposite to that of first mating. Body melanization is negatively correlated with second mating by male and positively with first mating (measured in terms of percent mated pairs). Mating latency during first (ML1) and second (ML2) male mating has a negative latitudinal cline, but slope values differ significantly as ML2 is great at higher latitudes as compared to ML1. The difference between ML1 and ML2 is non‐significant at lower latitudes. However, copulation period of second mating (CP2) has a negative latitudinal cline, whereas copulation period of first mating (CP1) has positive latitudinal cline. Next, the latency and copulation period differ significantly between first and second male mating treatments in within‐population analyses as well as in melanic strains. Furthermore, male remating ability (number of maximum successful remating attempts continuously by a male in 12 h) also follows negative latitudinal cline. The lower latitudinal lighter males have more remating ability as compared to darker males from higher latitudes.