SEX DIFFERENCES IN MATE RECOGNITION AND CONSPECIFIC PREFERENCE IN SPECIES WITH MUTUAL MATE CHOICE

Sexual isolation is often assumed to arise because choosy females recognize and reject heterospecific males as mates. Yet in taxa in which both males and females are choosy, males might also recognize and reject heterospecific females. Here, we asked about the relative contribution of the sexes to the strong sexual isolation found in limnetic–benthic species pairs of threespine sticklebacks, which show mutual mate choice. We asked whether males and females of the two species recognize conspecifics and also prefer to mate with them. We found evidence for mate recognition by both sexes but only females prefer conspecifics. The nature of male courtship depended on which species of female they were courting, indicating that males recognized conspecific females and differentiated them from heterospecifics. However, males courted both species of females with equal vigor and changed courtship in a manner that would increase the chance of mating with heterospecifics. Females both recognized conspecifics and strongly preferred them. They responded very little to heterospecific male courtship and almost never mated with them. Therefore, males are likely to undermine sexual isolation, but females uphold it. Despite mutual mate choice and mate recognition in both sexes, females are primarily responsible for sexual isolation in these taxa.     

Multiple male traits interact: attractive bower decorations facilitate attractive behavioural displays in satin bowerbirds

Sexually selected male courtship displays often involve multiple behavioural and physical traits, but little is known about the function of different traits in mate choice. Here, we examine female courtship behaviours to learn how male traits interact to influence female mating decisions. In satin bowerbirds (Ptilonorhynchus violaceus), successful males give highly aggressive, intense behavioural displays without startling females. Males do this by modulating their displays in response to female crouching, which signals the display intensity that females will tolerate without being startled. Females typically visit multiple males for multiple courtships before choosing a mate, and females show differing tolerance for intense displays during their first courtship with each male. We test three hypotheses that may explain this: (i) familiarity with the courting male; (ii) the order of the courtship in mate-searching; and (iii) the attractiveness of the courting male. We found that females are more tolerant of intense displays during first courtships with attractive males; this increased female tolerance may allow attractive males to give higher intensity courtship displays that further enhance their attractiveness. We then examined why this is so, finding evidence that females are less likely to be startled by males with better physical displays (bower decorations), and this reduced startling then contributes to male courtship success. This role of physical displays in facilitating behavioural displays suggests a novel mechanism by which multiple physical and behavioural traits may influence female choice.     

Absence of social facilitation of courtship in the wolf spider, Schizocosa ocreata (Hentz) (Araneae: Lycosidae)

Males of many animal species are reproductively limited by the difficulty and time costs of finding mates. Males of such species should be selected to take advantage of any cues that might reveal the location of prospective mates. Cues to female location are not restricted to those produced by females, but might also include the highly apparent courtship displays of males that have already found a female. By “eavesdropping” on these courting rivals, initiating sexual displays when courting rivals are detected (i.e., social facilitation of displays); males might effectively exploit the mate-searching efforts of their rivals. We tested the possibility that male Schizocosa ocreata wolf spiders exhibit social facilitation of courtship behaviors using a combination of live behavioral trials and video playback with single stimulus presentations. When exposed to visual cues from another male, male S. ocreata can discern the presence of another individual whether that individual is courting or not. However, we found no evidence of social facilitation of courtship or chemoexploratory behaviors in response to seismic or visual cues presented in isolation or combined. While complex, multimodal, male courtship signals are important in mate choice by female S. ocreata, males do not appear to use these cues to socially facilitate their own courtship.     

Firefly Courtship: Behavioral and Morphological Predictors of Male Mating Success in Photinus greeni

Differences in male mating success can generate selection on male morphological traits and courtship behaviors involved in male–male competition or female mate choice. In Photinus fireflies (Coleoptera: Lampyridae), courtship is based on bioluminescent flash signals produced by both sexes. We conducted field observations of Photinus greeni fireflies engaged in competitive courtships, in which females are able to simultaneously assess several males, to identify male morphological traits and courtship behaviors that might predict male mating success. Male morphological traits did not differ between males that successfully mated compared with unsuccessful males (dialoging males that did not mate). However, courtship behavioral interactions differed: successful males tended to have higher flash pattern rates (number of flash patterns per minute), and their courtship flashes were more likely to be answered by females. We also examined how the risk of predation by Photuris fireflies altered courtship behavior of their Photinus prey. When predatory Photuris fireflies were present, P. greeni females were less likely to mate, and showed decreased flash responses to most males. However, P. greeni males that did successfully mate in spite of Photuris presence were males that maintained high flash pattern rates that elicited female responses. These results suggest that both female mate choice and Photuris predation exert strong selective pressures on the evolution of courtship signals in Photinus fireflies.     

Female Choice or Male Sex Drive? The Advantages of Male Body Size during Mating in Drosophila Melanogaster

The mating success of larger male Drosophila melanogaster in the laboratory and the wild has been traditionally been explained by female choice, even though the reasons are generally hard to reconcile. Female choice can explain this success by virtue of females taking less time to mate with preferred males, but so can the more aggressive or persistent courtships efforts of large males. Since mating is a negotiation between the two sexes, the behaviors of both are likely to interact and influence mating outcomes. Using a series of assays, we explored these negotiations by testing for the relative influence of male behaviors and its effect on influencing female courtship arousal threshold, which is the time taken for females to accept copulation. Our results show that large males indeed have higher copulation success compared to smaller males. Competition between two males or an increasing number of males had no influence on female sexual arousal threshold;—females therefore may have a relatively fixed ‘arousal threshold’ that must be reached before they are ready to mate, and larger males appear to be able to manipulate this threshold sooner. On the other hand, the females’ physiological and behavioral state drastically influences mating; once females have crossed the courtship arousal threshold they take less time to mate and mate indiscriminately with large and small males. Mating quicker with larger males may be misconstrued to be due to female choice; our results suggest that the mating advantage of larger males may be more a result of heightened male activity and relatively less of female choice. Body size per se may not be a trait under selection by female choice, but size likely amplifies male activity and signal outputs in courtship, allowing them to influence female arousal threshold faster.     

Mate copying versus preference for actively courting males by female Japanese medaka (Oryzias latipes)

We determined whether female Japanese medaka (Oryzias laiipes)copied the choice of other females or independently preferredactively courting males. We allowed focal females to observeand subsequently choose between a male that courted and potentiallyspawned with a receptive female and a male that courted andwas rejected by an unreceptive female. When the receptive femaledid not spawn, the focal female preferred the male with thehigher courtship rate; whereas when the receptive female spawned,the focal female preferred the spawning male. Our results suggestthat female medaka prefer actively courting males, unless theyhave the opportunity to copy the mate choice of another female.     

Are you Paying Attention? Female Wolf Spiders Increase Dragline Silk Advertisements When Males do not Court

Females of many spider species invest in chemical advertisements to attract males, yet variation in investment relative to the presence or quality of males remains poorly understood. Males of the wolf spider Pardosa milvina court females longer and more intensively when in contact with female silk and also court more intensively when encountering silk from virgin rather than mated females; therefore, females may use silk as a medium to advertise their receptivity to mate. We estimated female investment in advertisements by measuring variation in the quantity and type of silk deposited by females in the presence or absence of males and among males that varied in their courtship intensity. We measured dragline silk, cord silk, and attachment disk deposition from females on gridded sheets of paper in response to four stimuli over a 30‐min period (n = 39/treatment): (1) an intensively (high) courting male with access to female silk, (2) a weakly courting or non‐courting male (low) without access to female silk, (3) no male present, but female silk present (silk control), and (4) no stimulus present (control). Females produced significantly more dragline silk and significantly less cord silk in the presence of low‐courting males compared to any other treatment, but we found no difference in attachment disk deposition across treatments. Our results suggest that females invest more heavily in dragline deposition when encountering low‐courting males. Additional studies are necessary to determine the relative role of different silk types in male–female sexual communication.     

Delayed courtship in the fiddler crab Uca musica terpsichores

Courting male fiddler crabs of the species Uca musica terpsichores congregate in the upper central portion of the colony, while receptive females leave their burrows located at the colony's periphery and wander among the communally displaying males prior to choosing a mate. I observed that courting males in a newly-established population were significantly smaller than courting males in large high-density colonies. This observation led to a series of translocation experiments designed to ascertain whether high population density influences the size (=age) at which males begin to court. Smaller courting males from a low-density population failed to court after being placed among larger courting males in a high-density population. The reciprocal translocation revealed that smaller noncourting males from the high-density population would start courting shortly after being placed in a low-density population. Smaller males placed in the high-density population were subsequently observed significantly further away from where they were initially placed than were larger males similarly translocated. The results suggest that smaller males delay courtship activities once they are forced, via encounters with larger males, to the periphery of the colony. I believe that both intrasexual selection (competition from larger males) and intersexual selection (female choice of large males) are responsible for the delay in male courtship activities.     

Inheritance of species differences in female receptivity and song requirement between Drosophila virilis and D. montana

Females of two Drosophila virilis group species, D. virilis and D. montana, have different requirements for the courting males. In the present study we have examined species differences in female receptivity and male courtship song requirement using females' acceptance signal instead of copulation for measuring female readiness to mate. Behavior of D. virilis and D. montana females and F1 and backcross hybrid females was observed in a single-pair courtships with D. virilis and D. montana males and normal and wingless (mute) F1 hybrid males. D. virilis females were very receptive and they commonly accepted the courtship of males unable to produce courtship song. D. montana females, on the contrary, had a low receptivity and these females accepted the courting male only after hearing his song. Interspecific F1 and backcross (BCm) females resembled D. virilis more than D. montana in their receptivity. These females, however, resembled D. montana in their song requirement. These findings suggest that female song requirement and female receptivity are determined by different genetic factors.     

Does sexual experience affect the strength of male mate choice for high‐quality females in Drosophila melanogaster?

Although females are traditionally thought of as the choosy sex, there is increasing evidence in many species that males will preferentially court or mate with certain females over others when given a choice. In the fruit fly, Drosophila melanogaster, males discriminate between potential mating partners based on a number of female traits, including species, mating history, age, and condition. Interestingly, many of these male preferences are affected by the male''s previous sexual experiences, such that males increase courtship toward types of females that they have previously mated with and decrease courtship toward types of females that have previously rejected them. D. melanogaster males also show courtship and mating preferences for larger females over smaller females, likely because larger females have higher fecundity. It is unknown, however, whether this preference shows behavioral plasticity based on the male''s sexual history as we see for other male preferences. Here, we manipulate the sexual experience of D. melanogaster males and test whether this manipulation has any effect on the strength of male mate choice for large females. We find that sexually inexperienced males have a robust courtship preference for large females that is unaffected by previous experience mating with, or being rejected by, females of differing sizes. Given that female body size is one of the most common targets of male mate choice across insect species, our experiments with D. melanogaster may provide insight into how these preferences develop and evolve.     

Male-male Competition and Female Mate Choice through Courtship Display in the Territorial Damselfish Stegastes nigricans

Both sexes of the herbivorous damselfish Stegastes nigricans maintain individual feeding territories. These territories are distributed contiguously, forming distinct colonies. Females visit male territories to spawn, and eggs are guarded by males until hatching. Male-male competition and female mate choice were studied in two colonies of different size compositions. Only larger individuals bred in both colonies. Some males in the large colony, that were larger than the breeding males in the small colony, did not succeed in reproducing probably because of severe attacks by the larger males while courting. However, females did not choose large size among breeding males. The most important male characteristic in female choice was the frequency of courtship displays in both colonies. Females in the large colony chose males mainly on the basis of the frequency of displays conducted in the females' territories, whereas females in the small colony chose males on the basis of the frequency of displays conducted in the males' territories. This difference may be a result of the difference in colony size. The distances between females' and males' territories were much greater in the large colony, and, because females cannot see courtship displays conducted in distant male territories, males in the large colony may have had to visit female territories frequently in order to conduct courtship near the females.     

Females lay fewer eggs for males with greater courtship success in a lekking Drosophila

The evolutionary basis for female mate choice in lek mating systems has been a common subject of research in animal behaviour. Because males apparently provide only gametes to females in lekking species, most research has focused on possible indirect (genetic) benefits that females might gain by discriminating among males. Despite the emphasis on indirect benefits, it has been recognized that females in non-resource-based systems such as leks could potentially gain direct benefits via mate choice if males varied in fertilization abilities, for example. Previous evidence has shown that females of a lekking Hawaiian Drosophila, D. grimshawi, vary in fecundity when mated to certain males, and that females possess preferences for vigorously courting males. This study tests the hypothesis that D. grimshawi females gain direct benefits by preferentially mating with more sexually vigorous males. Male courtship vigour (performance of wing and head-under-wing displays) and the consequences of female choice on offspring production were evaluated separately using different females. Unexpectedly, matings involving more vigorously courting males resulted in fewer offspring being produced. Reduced offspring number resulted because females laid fewer eggs when mating with males having greater courtship success. These results are discussed in light of sexual conflict and possible multiple mating by females. Females also demonstrated considerable variation in mating behaviour and behavioural variation was correlated with mating benefits. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.      

同种雄性竞争对手的存在对星豹蛛雄蛛求偶和交配行为的影响

越来越多的研究发现,雄性产生精子(精液)也需付出代价。雄性除了依据配偶质量和竞争对手的竞争强度适应性调整生殖投入外,雄性在求偶和交配行为上也相应产生适应性反应,求偶和交配行为具有可塑性。目前雄性求偶和交配行为可塑性研究主要集中于雌性多次交配的类群中,在雌性单次交配的类群中研究甚少。以雌蛛一生只交配一次而雄蛛可多次交配的星豹蛛为研究对象,比较:(1)前一雄性拖丝上信息物质对后续雄蛛求偶和交配行为的影响,(2)雌雄不同性比对雄蛛求偶和交配行为的影响。研究结果表明,星豹蛛前一雄蛛拖丝上的信息物质对后续雄蛛求偶潜伏期、求偶持续时间和交配持续时间都没有显著影响,但前一雄蛛拖丝上的信息物质对后续雄蛛求偶强度有显著抑制作用。同时,性比对星豹蛛雄蛛求偶和交配行为都没有显著影响。可见,星豹蛛雄蛛对同种雄性拖丝上的化学信息可产生求偶行为的适应性调整,而对性比不产生适应性反应。     

Female mate preference in goby Eviota prasina: do secondary sexual traits influence female choice?

Males of the small gobiid fish Eviota prasina have longer dorsal fins than females and use their dorsal fins for courtship displays and male-male competition. We examined the influence of male dorsal fin length as well as the frequency of courtship displays on female mate preference using sequential choice experiments. Females responded more frequently to courting males with longer dorsal fins than males with shorter dorsal fins. This indicates female mate preference on the basis of male dorsal fin length in this goby. In addition, the logistic regression analysis showed that male courtship frequency positively influenced female mate preference. Since males incur costs to produce and maintain longer dorsal fins and to perform frequent courtship displays, these secondary sexual traits may indicate the quality of physical characteristics. In E. prasina, only males conducted parental care for eggs in their nests. Therefore, females may be able to ensure greater survival rates as well as higher genetic quality of their offspring by choosing males with better qualities based on these male traits.     

Consistency of females’ stridulatory behaviour during inter‐sexual interactions in spiders

In a sexual context, it is expected that females base their choice of mate on the behaviours that males perform during courtship, as such behaviours are associated with the male's mate quality. Stridulation is one form of female communication in arthropods, for example, spiders. In spiders, stridulation during sexual interactions is relatively common in some groups but mainly restricted to males. In the pholcid spider Holocnemus pluchei (Pholcidae), both sexes have stridulatory organs. The aims of the present work were to: (a) determine possible differences in the frequency of occurrence of stridulation between females during inter‐sexual interactions, (b) establish female consistency in stridulation along repeated interactions and (c) analyse if female stridulation is associated with certain male behaviours during pre‐copulatory courtship and with male size. Female H. pluchei showed highly repeatable differences in their frequency of stridulation across consecutive encounters with males (ICC = 0.64). However, only a modest level of repeatability was detected in total time females spent stridulating across trials (ICC = 0.19). Females’ mean stridulatory behaviour did not change across ten consecutive trials spread across 20 days, and their behaviour was apparently unaffected by male persistence of copulatory attempted and/or size. These results imply that the frequency of female stridulatory behaviour is a trait that is highly characteristic of each individual. Finally, our work opens the door to determine whether behavioural consistency manifests in other ecological contexts and their functional implications.     

Size-biased Mating in Both Sexes of the Black-horned Tree Cricket, <Emphasis Type="Italic">Oecanthus nigricornis</Emphasis> Walker (Orthoptera: Gryllidae: Oecanthinae)

Previous studies on tree crickets have demonstrated female choice of males based on size and courtship feeding but less is known about sexual selection under conditions of direct mating competition. I studied courtship, aggression and mating of the black-horned tree cricket Oecanthus nigricornis (Walker) to test size-related sexual selection under conditions of direct sexual competition. Results show that larger individuals of both sexes mated more frequently than their smaller counterparts, and this was due to the ability of large individuals to out compete rivals. Large males achieved the advantage by aggressively reducing courtship by small males, whereas large females responded to male courtship more quickly but with little aggression. Although there was no evidence here for mate choice, there were advantages for having larger mates; fecundity increased with female size and spermatophores (which females consume after mating) increased with male size. Size of the specialized metanotal courtship gift, however, was not related to male size.     

Effects of Age and Experience on Male Mate Choosiness

Mate choosiness by males has been documented in many taxa but we still do not know how it varies with age even though such variation can be important for our understanding of sexual selection on females. Theory provides conflicting predictions: young males, who are less attractive to females than older males, may be less choosy, or older males, who face fewer expected future mating opportunities, may be less choosy. In our experiments with fruit flies (Drosophila melanogaster), young (1‐d‐old) males spent relatively less time courting recently mated females than did mature (4‐d‐old) males. Overall, there was a gradual decline in male mate choosiness from age 1–7 d. As male age was correlated with the duration of deprivation from females, we tested for the effect of deprivation and found that same‐age males previously exposed to females were choosier than female‐deprived males. We also assessed key male parameters that could affect choosiness and found that, compared to mature males, young males were less attractive to females, less competitive in intramale interactions and less fertile. Although the lesser attractiveness and competitiveness should select for lesser mate choosiness in young males, their limited fertility and more expected future mating opportunities seem to override the other factors and lead to high mate choosiness in young males. Overall, our data indicate that young males just after reaching sexual maturity are choosy and that subsequent exposure to females can maintain high levels of male mate choosiness with age. Hence, males can contribute much more to sexual selection than previously appreciated.     

Courtship and Female Competition in the Majorcan Midwife Toad,Alytes muletensis

The courtship and mating behaviour of A. muletensis are described based on observations of captive toads. Courtship is prolonged and complex, with both sexes participating actively. Either sex can escape from amplexus and may do so if the partner fails to respond appropriately to courtship manocuvres. Females control the pace and duration of courtship. Females unable to obtain a mate drop their eggs unfertilized. Both sexes produce courtship vocalizations and either sex may initiate courtship, although females were observed to do so only when they were in danger of dropping their eggs. Physical competition in the form of interference and grappling may occur between either males or females, but was observed more frequently between females. The active role played by females during courtship in this species is discussed with regard to sex-role reversal theory and opportunities for mate choice.     

Melodic males and flashy females: Geographic variation in male and female reproductive behavior in red‐eyed treefrogs (Agalychnis callidryas)

Geographic variation in courtship behavior can affect reproductive success of divergent phenotypes via mate choice. Over time, this can lead to reproductive isolation and ultimately to speciation. The Neotropical red‐eyed treefrog (Agalychnis callidryas) exhibits high levels of phenotypic variation among populations in Costa Rica and Panama, including differences in color pattern, body size, and skin peptides. To test the extent of behavioral premating isolation among differentiated populations, we quantified male advertisement calls from six sites and female responses to male stimuli (acoustic and visual signals) from four sites. Our results show that both male advertisement calls and female behavior vary among populations: Discriminant function analyses can predict the population of origin for 99.3% ± 0.7 of males based on male call (dominant frequency and bandwidth) and 76.1% ± 6.6 of females based on female response behavior (frequency and duration of visual displays). Further, female mate choice trials (n = 69) showed that population divergence in male signals is coupled with female preference for local male stimuli. Combined, these results suggest that evolved differences among populations in male call properties and female response signals could have consequences for reproductive isolation. Finally, population variation in male and female behavior was not well explained by geographic or genetic distance, indicating a role for localized selection and/or drift. The interplay between male courtship and female responses may facilitate the evolution of local variants in courtship style, thus accelerating premating isolation via assortative mating.     

Female Choice and the Consistency of Courtship Feeding in Black-horned Tree Crickets Oecanthus nigricornis Walker (Orthoptera: Gryllidae: Oecanthinae)

Courtship feeding in insects is often strongly correlated with insemination duration and therefore provides a potential postcopulatory episode of sexual selection. We tested whether courtship feeding and other courtship traits in the black-horned tree cricket Oecanthus nigricornis showed sufficient consistency potentially to respond to sexual selection by testing whether they differed significantly among males. Duration of courtship feeding differed among males when measured repeatedly and this caused significant differences in the duration of spermatophore attachment, a trait that determines the maximum duration of insemination and thus has important fitness consequences in crickets. We also partitioned variance in courtship behaviour between the sexes to test whether differences in courtship behaviour were attributable primarily to males, females or both sexes. Duration of spermatophore attachment was controlled by females and therefore represents a mechanism of female mate choice. Significant variation in duration of spermatophore attachment was associated with differences between individuals of both sexes. Differences among males indicate that females agree in their preference of certain males whereas differences among females indicate that females differ in their receptivity to postcopulatory courtship and insemination. The fact that differences among males in duration of spermatophore attachment were due to significant differences solely in the period of courtship feeding indicates that postcopulatory female choice was mediated through courtship feeding. Whether males manipulate female choices by allocating more or fewer resources requires further testing, but we found that males court some females more vigorously than others after females dismount. The number of previous mates had opposite effects on the duration of courtship feeding for the sexes, decreasing it for males but increasing it for females, and we discuss the possible causes of these results.