猫蚤的交配习性及雄蚤对雌蚤提取物的反应

在人工饲喂系统上研究了猫蚤的交配习性及雄蚤对雌蚤化学提取物的反应,结果表明,当5雌1雄在饲养盒内时,该雄虫可与其他雌虫进行多次交配,连续8小时内交配达48次,交配时间平均持续6．6分钟,两次交配的间隔时间平均为2．5分钟,当1雌5雄时,交配时间平均持续11．1分钟,交配间隔时间为12．1分钟,连续7小时内,该雌虫与雄虫交配27次,新羽化的雌雄虫吸血前不能交配,当把用雌虫提取物处理过的黑色滤纸片放进只有雄虫的饲养盒时,雄虫接触纸片的次数及雄－雄交配企图明显增加。     

Male Mating Tactics in the Shrimp Palaemonetes pugio (Decapoda, Caridea): Precopulatory Mate Guarding vs. Pure Searching

The guarding of females approaching a limited period of sexual receptivity is a common mating tactic of males. In many decapod crustaceans, such as the shrimp Palaemonetes pugio , females can only copulate during a short period after a reproductive molt. It has been predicted that mate guarding by males (pre-copula) evolves in such species if sex ratios are not highly female-biased and if males can detect the molt stage of the female. The mating tactics of males were investigated in P. pugio . Time-lapse video observations were made on interactions among two males, a pre-molt female, and an inter-molt female (20 replicates). There was no evidence that males recognized a pre-molt female until 24 h before its molt. Significant numbers of male contacts with pre-molt females occurred 1 h before and after the female molt. Copulation took place within 1–3 min of the molt. No behavior commonly associated with mate guarding in decapods was observed – no clasping, agonistic behavior, or close association. It is concluded that the male's mating tactic is pure searching, wherein males haphazardly contact many females in order to find a receptive one. The high encounter rate in nature of these very mobile, aggregated shrimps is proposed as the factor responsible for the evolution of pure searching. It is hypothesized that pure searching is the male tactic of the many species of decapod shrimps with small males, sexually monomorphic cheliped weapons, and aggregated populations.     

Situation exploitation: higher male mating success when female resistance is reduced by feeding

Optimal male and female mating rates rarely coincide. Males often shift the rate in their favor by either increased signaling and by overcoming female resistance to copulation. The concept of sensory exploitation posits that males produce signals that mimic naturally selected benefits and so deceitfully attract females. However, males also have to overcome female resistance to actual copulation. Males may do so by copulating during situations when the female's ability to resist is decreased because of competing naturally selected demands. Males of the common bedbug, Cimex lectularius , an obligate blood feeder, mate at a rate, and in a manner that is harmful to females. Females have to feed regularly to produce eggs, and during feeding female body volume increases by 300%. Choice trials using unfed and either fed or experimentally enlarged but unfed females showed that the increased postfeeding body volume of females attracted more male mating attempts, strongly reduced female resistance to male mating attempts and resulted in a net increase in female mating rate. Our results, therefore, suggest that males have increased mating success in a situation that females cannot avoid because it is naturally selected. Such "situation exploitation" of low resistance may be a common phenomenon.     

Extreme Promiscuity in a Mating System Dominated by Sexual Conflict

Coelopids live in wrack beds consisting of seaweed washed up on beaches. Their mating system is characterized by sexual conflict and convenience polyandry, with females resisting male mating attempts. We estimated the level of harassment by males and the success rate of rejection by females collected from a high density wild population. Males mounted a female every 8.41 min. Of these mounts 35% resulted in copulation. This suggests that females could be mated up to 5 times every 2 h. Females typically live for 3 weeks, and thus, could mate with hundreds of males during their lifetime. We found a 50:50 sex ratio throughout the wrack bed revealing that females do not avoid male harassment by leaving the wrack bed when not ovipositing.     

The role of female dominance hierarchies in the mating behaviour of mosquitofish

While studies of sexual selection focus primarily on female choice and male-male competition, males should also exert mate choice in order to maximize their reproductive success. We examined male mate choice in mosquitofish, Gambusia holbrooki, with respect to female size and female dominance. We found that the number of mating attempts made by a male was predicted by the dominance rank of females in a group, with dominant females attracting more mating attempts than subordinates. The number of mating attempts made by males was independent of the female size. The observed bias in the number of mating attempts towards dominant females may be driven either by straightforward male mate choice, since dominance and female fecundity are often closely related, or via the dominant females mediating male mating behaviour by restricting their access to subordinate females.     

Opportunities for female choice in the bed bug Cimex lectularius

Bed bugs are cited as exemplars of sexual conflict because mating can only occur via traumatic insemination. However, past antagonistic coevolution between the sexes does not necessarily preclude current female choice. Here, we investigate opportunities for precopulatory female choice in bed bugs. We examined whether females seek out mating opportunities when they gain the most benefit: when females are virgin and/or have recently fed. But, we found that female mating and feeding status had little effect on female attraction to males and male odor. To determine whether females approach male harborages (home crevices) to seek matings in nature, we investigated where matings occurred among unfamiliar pairs of bed bugs. We found that, despite female attraction to male odor, matings were most likely to take place in the female's harborage rather than the male's harborage. We also examined the effect of feeding on male and female ability to mate. Whereas previous research reported that engorgement impaired female ability to refuse matings, we found that male feeding status had a larger effect on the success of mating encounters than female feeding status. Fed males had poor mating success, suggesting that males may be faced with a trade‐off between mating and feeding.     

A survival and reproduction trade-off is resolved in accordance with resource availability by virgin female mosquitoes

The first 2-4 days after an Anopheles gambiae female mosquito emerges are critical to her survival and reproductive success. Yet, the order of behavioural events (mating, sugar feeding, blood feeding) during this time has received little attention. We discovered that among female cohorts sampled from emergence, sugar feeding had a higher probability than blood feeding of occurring first, and mating rarely occurred before a meal was taken. The night after emergence, 48% of females fed on sugar in mesocosms, and 25% fed on human blood; in the absence of sugar, 49% of females fed on human blood. After 5 days, 39% of the sugar-supplied females had blood fed and mated, and were fructose negative, whereas only 8% of the sugar-denied females had both blood fed and mated by this time. The model that best explained the transitions suggests that females made use of two distinct behavioural pathways, the most common one being to sugar-feed, then mate, and then seek blood. Other females sought blood first, then mated, and forwent a sugar meal. Lipid levels were higher in females with access to sugar than in females without access to sugar, particularly for those in later gonotrophic stages, while glycogen levels in the sugar-supplied group were higher throughout. In single-night experiments with females having had access to sucrose since emergence, those given a blood meal 1 day before spending a night with males had higher insemination rates than those not receiving the blood meal. These results indicate that the trade-off between survival and immediate reproduction is resolved by young adult females in accordance with availability of resources and gonotrophic state.     

Sperm precedence in the dragonfly Erythemis simplicicollis

Females of the dragonfly Erythemis simplicicollis (Say) (Odonata, Libellulidae) store enough sperm to fertilize 6–13 clutches of eggs laid on consecutive days. Nonetheless, they usually mate one or more times per day. Males wait for females at ponds containing surface vegetation on which the females lay eggs. Some males defend vegetation while other act as satellites. After mating, both types of males attempt to guard females against takeover by other males. Sperm precedence by male E. simplicicollis was studied using sterility produced by gamma irradiation to label sperm. After a dose-response analysis, males receiving a dose of 25 kiloroentgens (>99.9% sterile) were returned to their home pond as territory residents and satellites. Both types of males fertilized an average of 99.5% (range 97.3–100%) of the female's remaining clutch. After mating with a sterile male, females were isolated in a large cage, and eggs collected for several consecutive days. These clutches revealed that sperm mixing in the bursa of the females is essentially complete after 24 to 48 h and that the last male to mate had replaced an average of more than 57–75% of the sperm stored by female from previous matings. Thus, the last sperm in is the first sperm out fertilizing essentially all of the eggs laid soon (5–6 min) after the mating. Sperm from the most recent mating competes for fertilizations with sperm stored from previous matings only if the female oviposits on the following day without remating.     

Factors Affecting Mating Tactics in the Fiddler Crab, Uca vocans hesperiae

The mating strategies of male fiddler crabs are variable and highly flexible within species. In this study I examine three types of mating strategy used by individual male Uca vocans hesperaie. The most common strategy, termed a ‘standard gambit’, where males approached females at their burrow entrance and initiated courtship, accounted for 63% of mating attempts and 75% of successful matings. The rarest strategy (4% of mating attempts) was the ‘dig out’, where males attempted to mate with females whose burrows they had excavated. This strategy accounted for 19% of successful matings. ‘Herding’ behaviour which involved a male attempting to herd a female into a burrow and mate, contributed 33% of mating attempts but were generally unsuccessful, accounting for only 2.6% of successful matings. Males used more than one strategy during the study period. Smaller males used the standard gambit strategy more often than herding or dig outs while larger males used the herding strategy more often. There was no relationship between male size and mating success and males did not preferentially mate with females of a certain size. The predominant strategy adopted by males over the lunar cycle depended on female behaviour. Herding behaviour was induced by female wandering which escalated at full moon. Standard gambits were the commonest strategy adopted at and around new moon. The low success rate of male mating attempts (16%) indicates a reluctance by females to mate multiply. This may lead to conflict between the sexes because in fiddler crabs there is last male sperm precedence.     

A novel mating system in a solitary carnivore: the fossa

The mating strategies of male mammals have long been treated as broadly predictable on the basis of just two factors: the dispersion of females and the benefit of paternal care to male reproductive success. Female strategies and finer scale variations in mating systems remain poorly understood. In the fossa Cryptoprocta ferox , we had the rare opportunity to examine the mating system of a wild solitary carnivore directly, and identified features not classified or predicted by mating system theory. Males competed for mating opportunities at a traditional site monopolized by a female, high in a tree. The female mated with multiple males, repeatedly mated with some individuals and appeared to express mate choice. We observed three females thus, one replacing another on the site after each was seen to mate with four to five males over a period of 1–6 days. Copulations were prolonged (up to 3 h 8 min), involving a weak copulatory tie, and males appeared to guard females briefly after mating. Fossas are at low population density and do not use a den regularly; we suggest that both these factors impede individuals from locating a mate. We hypothesize that the observed mating system reduces this problem for both sexes, and increases the number of mates available to a female while ensuring a low risk of sexual harassment.     

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.     

In Pursuit of Females: Following and Contest Behavior by Males of a Namib Desert Tenebrionid Beetle,Physadesmia globosa

Male Physadesmia globosa beetles spend much of their active time following females, searching for single females, or contesting with other males for position behind females. Once paired with a female, a male does not feed, can seldom stay paired for more than a few min, and can mate only if the female stops moving. Females rarely stop moving unless they find a large food item, or burrow into the sand and become inactive. Thus, males expend great effort positioning themselves for opportunities to mate, which seldom arise. However, males do not display any alternative mating strategies, and none appear to be available, for females are scarce in relation to males, and do not become receptive to mating at any predictable times or places.     

Multiple mating and repeated copulations: effects on male reproductive success in red flour beetles

In many insects, both sexes mate multiple times and females use stored sperm for fertilizations. While males frequently engage in two distinct behaviours, multiple mating (with different females) and repeated copulations (with the same female), the reproductive consequences of these behaviours for males have been quantified for only a few species. In this study, males of the red flour beetle, Tribolium castaneum, were found to be capable of mating with as many as seven different virgin females within 15 min. Across sequential copulations with virgin females, there was no decline in either male insemination success or average female progeny production over 48 h. However, when males copulated with previously mated females, there was a significant decline in male paternity success across sequential copulations, possibly due to male sperm depletion. In separate experiments, T. castaneum males were found to engage in two to six repeated copulations with the same, individually marked female. These repeated copulations did not increase male insemination success, short-term female fecundity, or male paternity success. Repeated copulations may possibly play a role in sperm defence. This study indicates that males may frequently engage in multiple matings, but these additional matings may lead to diminishing male reproductive returns.     

Is egg carrying attractive? Mate choice in the golden egg bug (Coreidae,Heteroptera)

In several species of fish, females select males that are already guarding eggs in their nests. It is a matter of debate as to whether a female selects a good nest site for her offspring (natural selection) or a male for his attractiveness (sexual selection). The golden egg bug, Phyllomorpha laciniata Vill, resembles fish in the sense that mating males carry more eggs than single males, but in the bugs, female mate choice is decoupled from egg site choice. The sexual selection hypothesis predicts that if females select males using male egg load as a cue for male quality, they should not mate with a male when eggs are removed, regardless of his mating attempts. When individual females were enclosed with an egg-loaded male and an unloaded male, they mated equally often with both males, although the loaded males courted more. In addition, when only successful males were used, females mated equally often with the loaded male and the unloaded male irrespective of sex ratio. Male choice rather than female choice affected mating frequency when sex ratio was equal. Therefore, females do not select the male by the eggs he carries, but successful males may receive many eggs due to egg dumping by alien females while they mate or as a consequence of mate guarding.     

Diet affects female mating behaviour in a seed‐feeding beetle

In species where males provide nuptial gifts, females can improve their nutritional status and thus increase their fecundity by mating when in need of resources. However, mating can be costly, so females should only mate to acquire resources when the need for resources is large, such as when females are nutritionally‐deprived. Two populations of the seed‐feeding beetle Callosobruchus maculatus, a species that produces relatively large nuptial gifts, are used to test whether female nutritional status affects mating behaviour. Female access to water, sugar and yeast are manipulated and the fitness consequences of these manipulations are examined together with the effects of diet on the propensity of nonvirgin females to mate. Access to water has a small but significant effect on mass loss over time, lifespan and fecundity of females, relative to unfed controls. Access to sugar (dissolved in water) improves female fecundity and lifespan above that of hydrated females but access to yeast has no positive effects on female survival or reproduction. Diet has a large effect on both receptivity of nonvirgin females to a male and how quickly they accept that male. Unfed females are both more likely to mate, and accept a mate more quickly, than females provided access to water, which are more likely to mate and accept a mate more quickly than females provided with sugar. This rank order of behaviours matches the order predicted if females increase their mating rate when nutritionally deprived (i.e. it matches the effect of diet on female fitness). The results obtained also suggest that mate choice may be condition‐dependent: females from one population (Burkina Faso) show a preference for large males when well‐fed but not when unfed, although this result is not found in a second population (South India). It is concluded that nutritionally‐deprived females are more receptive to mates than are well‐fed females, consistent with the hypothesis that females ‘forage’ for nuptial gifts, or at least more willingly accept sperm in exchange for nuptial gifts, when they are nutritionally deprived.     

Assortative mating in fallow deer reduces the strength of sexual selection

Background

Assortative mating can help explain how genetic variation for male quality is maintained even in highly polygynous species. Here, we present a longitudinal study examining how female and male ages, as well as male social dominance, affect assortative mating in fallow deer (Dama dama) over 10 years. Assortative mating could help explain the substantial proportion of females that do not mate with prime-aged, high ranking males, despite very high mating skew. We investigated the temporal pattern of female and male matings, and the relationship between female age and the age and dominance of their mates.

Results

The peak of yearling female matings was four days later than the peak for older females. Younger females, and especially yearlings, mated with younger and lower-ranking males than older females. Similarly, young males and lower-ranking males mated with younger females than older males and higher-ranking males. Furthermore, the timing of matings by young males coincided with the peak of yearling female matings, whereas the timing of older male matings (irrespective of rank) coincided with the peak of older female matings.

Conclusions

Assortative mating, through a combination of indirect and/or direct female mate choice, can help explain the persistence of genetic variation for male traits associated with reproductive success.     

The effect of hunger on mating behaviour and sexual selection for male body size in Gerris buenoi

The set of mating behaviours expressed by an individual may depend upon the state of that individual and local environmental conditions. Understanding how these factors affect mating behaviours may elucidate how a mating system operates, and its consequences for the form and strength of sexual selection. We conducted two experiments on the water striderGerris buenoi to (1) determine the effect of hunger on the mating behaviour of both sexes and (2) examine female choice for large males. In our first experiment, we manipulated hunger (20 h starvation) in both sexes and recorded mating, male harassment, copulation duration and guarding duration. We predicted that hunger would increase female reluctance to mate because mating conflicts with foraging. Female hunger (20 h starvation) decreased mating rate by two-thirds but had no significant effect on male mating behaviour. In a second experiment, we examined the effect of female hunger, and resulting reluctance, on sexual selection for large male size. Hungry females (5 h starvation) were placed with two fed males (one large, one small) and we recorded male premating and mating behaviours. We observed significant large-male mating advantage when females were hungry, but not when satiated. Mating efforts (harassment, premating struggles) were similar for both male phenotypes in both female hunger treatments, suggesting that the mating advantage of large males resulted from increased reluctance of hungry females to mate. Neither male body size nor female hunger explained a significant amount of variation in copulation duration or guarding duration. We discuss our results in light of two competing hypotheses for female choice (active and passive) on male body size and suggest that passive choice for large males acts in this system. Copyright 2002 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour     

The complexity of mating decisions in stalk‐eyed flies

All too often, studies of sexual selection focus exclusively on the responses in one sex, on single traits, typically those that are exaggerated and strongly sexually dimorphic. They ignore a range of less obvious traits and behavior, in both sexes, involved in the interactions leading to mate choice. To remedy this imbalance, we analyze a textbook example of sexual selection in the stalk‐eyed fly (Diasemopsis meigenii). We studied several traits in a novel, insightful, and efficient experimental design, examining 2,400 male–female pairs in a “round‐robin” array, where each female was tested against multiple males and vice versa. In D. meigenii, females exhibit strong mate preference for males with highly exaggerated eyespan, and so we deliberately constrained variation in male eyespan to reveal the importance of other traits. Males performing more precopulatory behavior were more likely to attempt to mate with females and be accepted by them. However, behavior was not a necessary part of courtship, as it was absent from over almost half the interactions. Males with larger reproductive organs (testes and accessory glands) did not make more mating attempts, but there was a strong tendency for females to accept mating attempts from such males. How females detect differences in male reproductive organ size remains unclear. In addition, females with larger eyespan, an indicator of size and fecundity, attracted more mating attempts from males, but this trait did not alter female acceptance. Genetic variation among males had a strong influence on male mating attempts and female acceptance, both via the traits we studied and other unmeasured attributes. These findings demonstrate the importance of assaying multiple traits in males and females, rather than focusing solely on prominent and exaggerated sexually dimorphic traits. The approach allows a more complete understanding of the complex mating decisions made by both males and females.     

Female reproductive strategies in orangutans,evidence for female choice and counterstrategies to infanticide in a species with frequent sexual coercion

Intersexual conflicts over mating can engender antagonistic coevolution of strategies, such as coercion by males and selective resistance by females. Orangutans are exceptional among mammals for their high levels of forced copulation. This has typically been viewed as an alternative mating tactic used by the competitively disadvantaged unflanged male morph, with little understanding of how female strategies may have shaped and responded to this behaviour. Here, we show that male morph is not by itself a good predictor of mating dynamics in wild Bornean orangutans but that female conception risk mediated the occurrence and quality of male–female interactions. Near ovulation, females mated cooperatively only with prime flanged males who they encountered at higher rates. When conception risk was low, willingness to associate and mate with non-prime males increased. Our results support the hypothesis that, together with concealed ovulation, facultative association is a mechanism of female choice in a species in which females can rarely avoid coercive mating attempts. Female resistance, which reduced copulation time, may provide an additional mechanism for mate selection. However, coercive factors were also important as prime males were frequently aggressive to females and females used mating strategies consistent with infanticide avoidance.     

The effects of exposure to seaweed on willingness to mate, oviposition, and longevity in seaweed flies

Abstract  1. Large male seaweed flies (Diptera: Coelopidae) are more likely to mate than smaller males. This is due to sexual conflict over mating, by which females physically resist male attempts to copulate. In some species, large males are simply more efficient at overpowering female resistance.
2. Female reluctance to mate is likely to have evolved due to the costs of mating to females. In many dipterans, males manipulate female behaviour through seminal proteins that have evolved through sperm competition. This behavioural manipulation can be costly to females, for example forcing females to oviposit in sub-optimal conditions and increasing their mortality.
3. Previous work has failed to identify any ubiquitous costs of mating to female coelopids. The work reported here was designed to investigate the effects of exposure to oviposition sites ( Fucus algae) on the reproductive behaviour of four species of coelopid. Algae deposition in nature is stochastic and females mate with multiple males in and around oviposition sites. Spermatogenesis is restricted to the pupal stage and there is last-male sperm precedence. It was predicted that males would avoid wasting sperm and would be more willing to mate, and to remain paired with females for longer, when exposed to oviposition material compared with control males. Females were predicted to incur longevity costs of mating if mating increased their rate of oviposition, especially in the presence of algae.
4. The behaviour of males of all four species concurred with the predictions; however mating did not affect female receptivity, oviposition behaviour, or longevity. Exposure to algae induced oviposition and increased female mortality in all species independently of mating and egg production. The evolutionary ecology of potential costs of mating to female coelopids are discussed in the light of these findings.