Female signals enhance the efficiency of mate assessment in satin bowerbirds (Ptilonorhynchus violaceus)

Recent evidence suggests that males adjust their sexually selecteddisplay traits in response to female behaviors during courtships.Little is known, however, about whether females signal to influencemale displays and whether females benefit from this interaction.Male courtship displays in the satin bowerbird (Ptilonorhynchusviolaceus) are highly intense and aggressive. Females may usethese displays as indicators of mating benefits, but these displaysoften startle females and disrupt courtship. Previous studieshave shown that successful males decrease female startling byadjusting their display intensity according to female crouchingbehaviors, suggesting that crouching behaviors function as signals.Here we address whether female crouching is a signal by usingobservations of natural courtship behaviors. In addition, weexamine why females differ in signaling and whether femalesbenefit from signaling. First, we find that female crouchingis related to the likelihood that females will be startled bymale displays, suggesting that crouching signals the degreeof display intensity that females will tolerate from a malewithout being startled. Second, we find that female tolerancefor intense display increases during successive courtships asfemales assess potential mates, and that female tolerance mayalso be affected by age and condition. Third, we find evidencethat females that reduce startling by signaling their intensitytolerance are more efficient in mate searching. These resultssuggest that females signal to influence how males display theirsexually selected traits, and by doing so, females may increasetheir benefits in mate choice.     

Male adaptations to minimize sexual cannibalism during reproduction in the funnel‐web spider Hololena curta

Males of many spider species risk being attacked and cannibalized while searching for, courting, and mating with conspecific females. However, there are exceptions. We show that the funnel‐web spider, Hololena curta, has 3 adaptations that minimize risk to males during courtship and mating, and enhance reproductive success. First, males detected chemical or tactile signals associated with webs of virgin females, and differentiated them from webs of mated females, enabling males to increase encounter rates with virgin females and avoid aggressive mated females. Second, males produced stereotyped vibrational signals during courting which induced female quiescence and suppressed female aggression. Third, when touched by males, sexually receptive females entered a cataleptic state, allowing males to safely approach and copulate. Because males can mate multiple times and the sex ratio in natural populations of H. curta is female biased, overall reproductive output is likely increased by males of this species avoiding sexual cannibalism.     

Female choice for male motor skills

Sexual selection was proposed by Darwin to explain the evolution of male sexual traits such as ornaments and elaborate courtship displays. Empirical and theoretical studies have traditionally focused on ornaments; the reasons for the evolution of elaborate, acrobatic courtship displays remain unclear. We addressed the hypothesis that females choose males on the basis of subtle differences in display performance, indicating motor skills that facilitate survival. Male golden-collared manakins (Manacus vitellinus) perform elaborate, acrobatic courtship displays. We used high-speed cameras to record the displays of wild males and analysed them in relation to male reproductive success. Females preferred males that performed specific display moves at greater speed, with differences of tens of milliseconds strongly impacting female preference. In additional males, we recorded telemetrically the heart rate during courtship using miniature transmitters and found that courtship is associated with profoundly elevated heart rates, revealing a large metabolic investment. Our study provides evidence that females choose their mates on the basis of subtle differences in motor performance during courtship. We propose that elaborate, acrobatic courtship dances evolve because they reflect motor skills and cardiovascular function of males.     

Within‐Species Mate Preferences Do Not Contribute to the Maintenance of Sexually Monomorphic Mating Signals in Green Lacewings

We know much less about the evolutionary forces and constraints that maintain similar mating displays in females and males than we do about sexually dimorphic mating displays. Both female and male green lacewings have sexually monomorphic vibrational mating signals and are equally choosy against heterospecific mating signals. This similarity in between‐species sex roles may explain a large part of the presence of species‐specific female signals in these species, but does not necessarily predict why female and male signals are similar. We tested for within‐species sex‐specific similarities in mate preferences in Chrysoperla lucasina that may contribute to the maintenance of sexually monomorphic mating signals in this species. We found weak preferences and low levels of discrimination for signals with varying fine‐scale temporal features (volley duration, period, and volley‐duty cycle). The longer signals that both sexes produced in response to playback were sexually monomorphic, but some females and most males also produced shorter signals with significantly reduced volley durations and periods. Notably, all of these signals had indistinguishable volley‐duty cycles, the ratio of volley duration to volley period. We propose that mating signals in C. lucasina are maintained in both sexes because of similar between‐species mate preferences, but the sexually monomorphic mating signals cannot be attributed to significant within‐species mate preferences. What differences are present in within‐species sex roles may be resolved by a male‐biased signal polymorphism, in long and short signals that are hypothesized to have distinct functions during mate calling and courtship.     

拟环纹豹蛛雄蛛触肢上黑白相间毛饰物的功能

狼蛛科雄蛛附肢上多样化的饰装往往与求偶行为相偶联,这些特殊的饰装通常被认为是雌性选择的结果。拟环纹豹蛛Pardosa pseudoannulata,属狼蛛科豹蛛属,雄蛛触肢胫节密被白毛,跗舟密被黑毛,具有典型的性二型现象;同时,只有成熟的雄蛛才展现触肢黑白相间的毛饰物。推测拟环纹豹蛛雄蛛触肢这种黑白相间的毛饰物可能在物种识别中具重要作用。在室内我们拟通过涂抹操作对拟环纹豹蛛雄蛛触肢黑白相间毛饰物的功能进行分析。实验分为4组,分别是对照组(A组,雄蛛不做任何处理)、雄蛛触肢白色胫节全部涂成黑色(B组)、雄蛛触肢黑色跗舟全部涂成白色(C组)和雄蛛触肢的黑色跗舟被涂成黑色(D组),然后采用雌雄配对进行求偶交配行为测定。实验结果表明,B组雄蛛的交配成功率显著低于A、C和D组的雄蛛,而后3组雄蛛的交配成功率无显著差异。相反,B组雄蛛被雌蛛相食百分率显著高于其它3组。可见拟环纹豹蛛雄蛛触肢上黑白相间毛饰物,尤其是其胫节上的白色饰物在雌蛛种间识别中起重要作用。     

Seasonal Variation in Mate Choice of Photinus ignitus Fireflies

Mate choice by either sex may vary with changes in the associated costs and benefits, determined by factors such as the availability of potential mates and variation in mate quality. We examined seasonal variation in operational sex ratio, courtship behavior, spermatophore mass, egg count, and the relationship between morphological traits and mating success in Photinus ignitus fireflies to determine if mate choice in either sex varied with the availability and relative reproductive investment of fertilizable females and sexually active males. Successfully mating males had larger lanterns than unsuccessful males when the operational sex ratio was male‐biased. In addition, female responsiveness to male signals increased as the number of courting males decreased, and male spermatophore mass decreased with body size across the mating season. Successfully mating females had larger body mass than unsuccessful females. Female body mass predicted egg count and female rejection by males increased as the season progressed and female size decreased. These results suggest that both male and female P. ignitus exhibit mate choice, and that such choice is influenced by seasonal variation in the abundance and quality of potential mates.     

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。     

Do Male Veiled Chameleons,Chamaeleo calyptratus,Adjust their Courtship Displays in Response to Female Reproductive Status?

Variation in male courtship behavior may be due to inherent differences among males or may arise from males adjusting their courtship displays according to female responsiveness. Female veiled chameleons, Chamaeleo calyptratus , exhibit two distinctive suites of body coloration and behavior patterns that vary according to receptive and non-receptive stages of their reproductive cycle. We presented male chameleons with both receptive and non-receptive females, and recorded differences in their mating frequency, courtship intensity and courtship behavior patterns. As expected, males were more likely to court and attempt mating with receptive females. Although fewer males courted non-receptive females, their courtship displays were significantly longer than those directed towards receptive females. Males also adjusted the contents of their displays according to female reproductive condition. Certain behavior patterns were unique to courtship displays directed towards each class of females. Males exhibited the behavior pattern `head roll' only when paired with receptive females, and `chin rub' was displayed only during courtship of non-receptive females. We hypothesize that these differences in male courtship frequency, intensity and content reflect differences in female reproductive value. Although males may benefit from mating with both receptive and non-receptive females, the costs associated with courtship may depend on female responsiveness. Thus, males adjust their courtship tactics accordingly.     

Evidence of Monandry in a Mosquito (<Emphasis Type="Italic">Sabethes cyaneus</Emphasis>) with Elaborate Ornaments in Both Sexes

Despite the benefits of multiple mating to females many mosquitoes appear to be monandrous. Members of the mosquito tribe Sabethini are unique among the mosquitoes for they possess iridescent scales and elaborate ornaments in both sexes. Additionally, this tribe boasts the only reported cases of courtship display within the mosquitoes. Due to these singular traits and behaviors, we predicted that members of this tribe have a different mating system with relatively high female mating rate. We tested this prediction in the ornamented mosquito Sabethes cyaneus. Contrary to our prediction, however, females were monandrous throughout their lifetime and multiple gonotrophic cycles. We discuss the possible implications of monandry on the evolution of sexually homologous ornaments, with particular consideration of mutual mate choice.     

Differences in potential reproductive rates of male and female seahorses related to courtship roles

Dwarf seahorses, Hippocampus zosterae (Syngnathidae), are distinguished by extreme morphological specialization for paternal care, the formation of monogamous pair bonds and mating repeatedly over the course of a breeding season. To determine the potential reproductive rates of male and female dwarf seahorses, we measured (1) the maximum number of offspring produced per breeding cycle when sexually receptive mates were unlimited, and (2) the relative time each sex was unavailable for mating ('time out'). We paired sexually isolated males and females with sexually receptive partners and observed them from the day of introduction through to copulation, to determine the length of time it takes each sex to prepare to mate. We conducted additional experiments to determine the length of gestation, which when added to the time needed to prepare to mate and copulate gives an estimate of total reproductive cycle duration, T. We estimated potential reproductive rate by dividing the mean number of offspring produced per breeding cycle by the duration of the breeding cycle (T). We estimated reproductive 'time out' by identifying the period of time males and females were physiologically capable of mating ('time in', S) and subtracting time S from time T. When provided with sexually receptive partners, females took 2 days longer than males to complete courtship and copulation, but neither males nor females remated during gestation. Therefore, males could potentially produce 17% more offspring than females over the course of one breeding season. Females had reproductive 'times out' 1.2 times longer than did males, as they were only capable of mating during the 4 h directly preceding copulation. Thus, H. zosterae males have higher potential reproductive rates and shorter reproductive 'times out' compared with H. zosterae females. These results and previous work indicating that seahorses display traditional courtship roles support the prediction that the sex having the higher potential reproductive rate, or equivalently, the shorter 'time out', will compete more intensely for access to the opposite sex. Copyright 2000 The Association for the Study of Animal Behaviour.     

Reproductive Signals of Female Lizards: Pattern of Trait Expression and Male Response

Relative to the volume of studies concerning the function and evolution of male‐biased sexually dimorphic traits, instances of female‐biased sexual dimorphisms remain largely unstudied, especially in species with conventional sex roles. I investigated the signal function of a female‐specific ornamental trait using the striped plateau lizard (Sceloporus virgatus, Phrynosomatidae) as a model system. During the reproductive season, female S. virgatus develop orange color on their throats that is absent in conspecific males. I established the relationship between color expression and female reproductive state, and determined male response to female color. I show that dynamic changes occurring within the color patch can potentially identify each stage of the female reproductive cycle, largely because of a lag in patch growth relative to color intensification. Sexual receptivity is associated with intense patches rapidly growing in size; ovulation occurs near peak color expression; and the unreceptive period is associated with large patches fading in intensity. Because females express orange color during both the receptive and unreceptive periods, the pattern of color expression is consistent with the courtship‐stimulation and courtship‐rejection hypotheses of signal function. Males may preferentially associate with females that have more highly developed color patches during the courtship season, and/or ignore such females when they are unreceptive. An examination of male behavior towards unfamiliar females indicates that female color has a role in courtship stimulation but has little, if any, role in courtship rejection. During the pre‐mating season, males maintained significantly closer affiliation with, and tended to perform more social behavior towards females with more intense color. During the post‐mating season, female color had no apparent effect on male behavior. The evolution and current function of female ornaments may vary among taxonomically‐related species as a result of differences in ecology, social system, and life‐history.     

Sexually selected male weapon is associated with lower inbreeding load but higher sex load in the bulb mite

Elaborate sexually selected ornaments and armaments are costly but increase the reproductive success of their bearers (usually males). It has been postulated that high-quality males can invest disproportionately more in such traits, making those traits honest signals of genetic quality. However, genes associated with such traits may have sexually antagonistic effects on fitness. Here, using a bulb mite Rhizoglyphus robini, a species in which a distinct dimorphism exists between males in the expression of a sexually selected weapon, we compare inbreeding and gender load between lines derived from armed fighters and unarmed scramblers. After four generations of sib-mating, inbreeding depression for female fitness was significantly lower in fighter-derived lines compared to scrambler-derived lines, suggesting that fighter males had significantly higher genetic quality. However, outbred females from fighter-derived lines had significantly lower fitness compared to outbred females from scrambler-derived lines, demonstrating significant gender load associated with the presence of a sexually selected male weapon. Our results imply that under outbreeding, genetic benefits of mating with bearers of elaborate sexually selected traits might be swamped by the costs of decreased fitness of female progeny due to sexually antagonistic effects.     

Sexual signals and mating patterns in Syngnathidae

Male pregnancy in the family Syngnathidae (pipefishes, seahorses and seadragons) predisposes males to limit female reproductive success; sexual selection may then operate more strongly on females and female sexual signals may evolve (sex-role reversal). A bewildering array of female signals has evolved in Syngnathids, e.g. skin folds, large body size, colouration, markings on the body and elaborate courtship. These female sexual signals do not seem quantitatively or qualitatively different from those that evolve in males in species with conventional sex roles where males provide females or offspring with direct benefits. In several syngnathid species, males also evolve ornaments, females are choosy in addition to being competitive and males compete as well as choosing partners. Thus, sex roles form a continuum, spanning from conventional to reversed within this group of fishes. Cases are presented here suggesting that stronger sexual selection on females may be most extreme in species showing classical polyandry (one male mates with several females, such as many species where males brood their eggs on the trunk), intermediate in polygynandrous species (males and females both mate with more than one partner, as in many species where males brood their eggs on the tail) and least extreme, even exhibiting conventional sex roles, in monogamous species (one male mates solely with one female, as in many seahorses and tropical pipefishes). At the same time caution is needed before unanimously establishing this pattern: first, the connection between mating patterns, strength of sexual selection, sex roles and ornament expression is far from simple and straightforward, and second, knowledge of the actual morphology, ecology and behaviour of most syngnathid species is scanty. Basically only a few Nerophis, Syngnathus and Hippocampus species have been studied in any detail. It is known, however, that this group of fishes exhibits a remarkable variation in sex roles and ornamentation, making them an ideal group for the study of mating patterns, sexual selection and sexually selected signals.     

Sexually selected sexual selection: Can evolutionary retribution explain female ornamental colour?

By preferring mates with increasingly costly ornaments or courtship displays, females cause an escalation of male reproductive costs. Such increased costs should promote male selectivity based on fecundity‐linked female attributes, leading to female ornamentation in species with traditional sex roles. Consequently, female ornamentation should evolve more frequently in taxa where male reproduction is costly than in comparable taxa where it is cheaper. We assessed the prevalence of female ornamental colouration in two clades of viviparous cyprinodontid fish: the Goodeinae, where stringent female choice imposes male mating costs, and the Poeciliinae, whose males can circumvent female mate choice. We found that although in the Poeciliinae female ornamental colour is a correlated, but paler version of male coloration, females of the Goodeinae often display vivid ornamental colours that are distinct from those of males. Thus, male and female ornaments are not (phylo)genetically correlated in the Goodeinae. Furthermore, phylogenetic signal on male and female colour is clearly detectable in the Poeciliinae, but absent in the Goodeinae, suggesting that ornamental colour of males and females in the latter may be the consequence of selection. Given that enforceable female choice has promoted male ornaments, we propose that evolutionary retribution has promoted distinct female ornaments in the Goodeinae.     

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.     

Male sexual ornament size is positively associated with reproductive morphology and enhanced fertility in the stalk-eyed fly <Emphasis Type="Italic">Teleopsis dalmanni</Emphasis>

Background  

Exaggerated male ornaments and displays often evolve in species where males only provide females with ejaculates during reproduction. Although "good genes" arguments are typically invoked to explain this phenomenon, a simpler alternative is possible if variation in male reproductive quality (e.g. sperm number, ejaculate content, mating rate) is an important determinant of female reproductive success. The "phenotype-linked fertility hypothesis" states that female preference for male ornaments or displays has been selected to ensure higher levels of fertility and has driven the evolution of exaggerated male traits. Females of the stalk-eyed fly Teleopsis dalmanni must mate frequently to maintain high levels of fertility and prefer to mate with males exhibiting large eyespan, a condition-dependent sexual ornament. If eyespan indicates male reproductive quality, females could directly increase their reproductive success by mating with males with large eyespan. Here we investigate whether male eyespan indicates accessory gland and testis length, and then ask whether mating with large eyespan males affects female fertility.     

Exploring the influence of individual courtship behaviors on male mating success in a blow fly

Male courtship behavior and displays influence female mating decisions, and therefore affect mating success in a diverse range of organisms. While there is substantial evidence confirming that females prefer males who invest more in courtship, less attention has been paid to the relative importance of individual behaviors, and the discrete sequences of courtship that result in mating success. The small hairy maggot blow fly, Chrysomya varipes, performs stereotyped courtship behaviors, involving orienting, tapping, waving, arching, wing vibration and mounting. This study aimed to quantify male investment in specific courtship behaviors, and compare courtship investment and behavioral transitions between males who gained mating success (successful males) and those that did not (unsuccessful males). Our results show that mating success was influenced by the behaviors orienting, tapping, arching and mounting. Behavioral transitions revealed a distinct pattern of behaviors leading to a mating attempt, and some differences were observed between successful and unsuccessful males. Overall, our findings suggest that female mating decisions were based on differences in specific male courtship behaviors. This detailed observational study has quantified multiple courtship behaviors for the first time in C. varipes, and highlights the importance of considering multiple behavioral traits when exploring the influence of male courtship on mating success.     

Sexual Experience Enhances Drosophila melanogaster Male Mating Behavior and Success

Competition for mates is a wide-spread phenomenon affecting individual reproductive success. The ability of animals to adjust their behaviors in response to changing social environment is important and well documented. Drosophila melanogaster males compete with one another for matings with females and modify their reproductive behaviors based on prior social interactions. However, it remains to be determined how male social experience that culminates in mating with a female impacts subsequent male reproductive behaviors and mating success. Here we show that sexual experience enhances future mating success. Previously mated D. melanogaster males adjust their courtship behaviors and out-compete sexually inexperienced males for copulations. Interestingly, courtship experience alone is not sufficient in providing this competitive advantage, indicating that copulation plays a role in reinforcing this social learning. We also show that females use their sense of hearing to preferentially mate with experienced males when given a choice. Our results demonstrate the ability of previously mated males to learn from their positive sexual experiences and adjust their behaviors to gain a mating advantage. These experienced-based changes in behavior reveal strategies that animals likely use to increase their fecundity in natural competitive environments.     

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.     

Co-option of male courtship signals from aggressive display in bowerbirds

The pre-existing trait hypothesis suggests that females evolve a mating preference for an already existing male trait. This hypothesis poses a simple resolution to Darwin's long-standing question of how elaborate, male display traits evolve. The frequently observed convergence of aggressive and courtship displays across a wide array of species provides the only current support for this hypothesis. Here we provide much more detailed supporting evidence from bowerbird skrraa calls used in aggression and courtship. Consistent with the pre-existing trait hypothesis we show that (i) putatively co-opted skrraa calls used in courtship and aggression are homologous, (ii) skrraa calls were used in aggression in bowerbirds before being used in courtship, (iii) historically, intense, aggressive-like courtship calls were present near the time of co-option, and (iv) bower types contemporaneous with co-option emphasize design features that provide females protection from the adverse effects of intense courtship displays. These results, plus evidence for a female preference for males with intense aggressive-like courtship skrraa calls, suggest that aggressive skrraa calls have been co-opted for use in male courtship display