Species-Specificity of Chemical Signals: Silk Source Affects Discrimination in a Wolf Spider (Araneae: Lycosidae)

Female spiders deposit chemical cues that elicit male courtship behavior with silk. These cues are often assumed to be species-specific although male spiders may court in response to chemical cues of closely-related species. We used behavioral assays to test the extent of species discrimination of female chemical cues by male Schizocosa ocreata, a wolf spider (Lycosidae). Discrimination, expressed as relative courtship intensity of males, varied significantly with phylogenetic distance. Males did not discriminate between female cues of conspecifics and a sibling species, S. rovneri. Courtship response was intermediate for another species within the ocreata clade and not different from control for spiders outside the clade. These findings support the sibling species status of S. ocreata and S. rovneri, and also suggest the composition of female chemical signals is conserved across closely related wolf spider species.     

Choosing a mate in a high predation environment: Female preference in the fiddler crab Uca terpsichores

The interplay between a receiver's sensory system and a sender's courtship signals is fundamental to the operation of sexual selection. Male courtship signals that match a female receiver's preexisting perceptual biases can be favored yet the message they communicate is not always clear. Do they simply beacon the male's location or also indicate his quality? We explored this question in a species of fiddler crab Uca terpsichores that courts under elevated predation risk and that mates and breeds underground in the safety of males' burrows. Sexually receptive females leave their own burrows and are thereby exposed to avian predators as they sequentially approach several courting males before they choose one. Males court by waving their single greatly enlarge claw and sometimes by building a sand hood next to their burrow entrance. Hoods are attractive because they elicit a risk‐reducing orientation behavior in females, and it has been suggested that claw waving may also serve primarily to orient the female to the male. If the wave communicates male quality, then females should discriminate mates on the basis of variation in elements of the wave, as has been shown for other fiddler crabs. Alternatively, variation in elements of the claw waving display may have little effect on the display's utility as a beacon of the location of the male and his burrow. We filmed courting males and females under natural conditions as females responded to claw waving and chose mates. Analysis of the fine‐scale courtship elements between the males that females rejected and those they chose revealed no differences. When predation risk during courtship is high, males' courtship displays may serve primarily to guide females to safe mating and breeding sites and not as indicators of male quality apart from their roles as beacons.     

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。     

Complex Courtship Behavior in the Striped Ground Cricket, Allonemobius socius (Orthoptera: Gryllidae): Does Social Environment Affect Male and Female Behavior?

Complex courtship in the striped ground cricket, Allonemobius socius, involves a series of behaviors alternating between the sexes. We examined if complex courtship allows either or both genders to evaluate their mate and how mating behavior changes in different social environments. While complex courtship may allow discrimination by both sexes, here only females exhibited a preference. Males did not alter their courtship behavior or change spermatophore size for different size females. In contrast, females initiated copulation more quickly with bigger males possessing bigger spermatophores. In a different social environment (additional male, female, or both), males were less likely to omit courtship songs and female discrimination of mates changed. The distinct differences in male and female behavior suggest that subtle changes in social environment can have important consequences in structuring courtship and mating behavior.     

Sexual Selection in Black Morph Girardinus metallicus (Pisces: Poeciliidae): Females Can Spot a Winner (But We Cannot)

Male–male competition may interfere with the ability of females to choose mates by interrupting courtship or by favoring highly aggressive males who may damage females during mating attempts. Alternatively, females may benefit by mating with dominant males, and female choice and male–male competition may therefore act in unison. The same traits, including aggressiveness, may indicate male quality to females and to rivals. We investigated sexual selection in the black morph of the endemic Cuban poeciliid fish, Girardinus metallicus, to ascertain the links between morphological and behavioral traits and success in intra‐ and intersexual selection. Males conspicuously exhibit their black ventral surface and gonopodium to females during courtship. Dichotomous choice tests revealed female association preferences for certain males, and those same males were more successful in monopolizing access to females when the fish were allowed to directly interact. Dominant males followed, courted, and copulated with females more than subordinate males within a pair, and it appears that females could either assess dominance based on cues we did not measure, or could influence subsequent mating success by their behavior during the dichotomous choice trials. There was an interaction between black status (i.e., whether the male in each pair had more or less ventral black coloration than the other male in that pair) and dominance, such that low‐black dominant males courted early and then shifted to following females, whereas high‐black dominant males courted far more later in the observation period. These results hint at the importance for sexual selection of the interplay between a static morphological trait (black coloration) and a dynamic behavioral trait (aggressiveness), but the functional significance of the courtship display remains a mystery.     

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.     

No Coolidge Effect in Decorated Crickets

Female decorated crickets, Gryllodes sigillatus , obtain genetic benefits by mating with different males and, when given a choice, prefer novel males over previous mates. It is unknown, however, whether males exhibit a similar preference for novel females. Although female crickets control copulation, there are at least two ways in which males can exercise choice: (1) the amount of courtship directed towards prospective mates and (2) the size of the spermatophore transferred to the female at mating. To determine whether males devote more courtship effort to novel females while controlling for female behavioral cues, male courtship effort toward two dead females, one, a previous mate and the other, a novel female, was measured. To determine whether males manufacture larger spermatophores when paired with novel females, males were mated to novel or previous mates, and the different components of the spermatophore weighed. Males did not spend more time courting dead novel females than previous mates. There was no difference in the latency to remating of males confined with novel females and those paired with previous mates, and there was no difference in the mass of spermatophores transferred to novel and familiar females. Contrary to previous studies in other taxa, this study suggests that male crickets do not prefer novel mates and thus, are not subject to the Coolidge effect. Although mating with novel females may be beneficial to males, selection on males to identify and discriminate against previous mates may be relaxed because of a strong female preference for novel males.     

Mutual Mate Assessment in Wolf Spiders: Differences in the Cues Used by Males and Females

When males engage in conspicuous courtship displays, it seems obvious that females would use characteristics of that display in mating decisions. However, males must also have a way to identify and evaluate females prior to engaging in what might be a costly mating ritual. Although it was known that female wolf spiders of the species Pardosa milvina (Araneae; Lycosidae) attract males using volatile chemical cues, the nature of the cues used by males and females in mate selection had not been investigated. Specifically we determined whether males could detect the mating status of the female and if chemotactile cues from the female played a role in that process. In addition, we quantified conspicuous aspects of the male courtship (leg raises and body shakes) to determine if courtship intensity was related to female choice. Although repeated mating occurred in our studies, males were more likely to court and mate with virgin females. Males used substrate‐borne cues deposited by females to discriminate between mated and virgin females. Females used the conspicuous behaviors of males during courtship, body shakes and leg raises, in mate selection. Thus males and females use different kinds of information and different sensory modalities to assess the suitability of a potential mate.     

Signaling by Protrusive Scent Glands in Cave Crickets,Troglophilus neglectus Krauss (Orthoptera: Rhaphidophoridae), is Primarily Involved in Male-male Agonism

Males of several species of cave crickets (Rhaphidophoridae) possess protrusive abdominal scent glands, which are generally presumed to influence female behavior before mating. The validity of this hypothesis, as well as of the alternative possibility of the signal being designed for the rivals, was tested in Troglophilus neglectus by describing the detailed context and the consequences of such signaling by gland protrusion in the mating period. Small groups of both sexes were observed under naturalistic conditions, using interval and focal behavioral sampling. The frequency of gland protrusion increased progressively in both experimental seasons, and was expressed in solitary males as well as in their interactions with both mates and rivals. Such signaling, however, was not an obligatory part of courtship and pre-mating behavior in general, and caused neither female attraction nor influenced the courtship success. The males protruded the glands significantly more frequently during the antennal contacts with another male than during contacts with a female. Of the different behaviors expressed in the inter-male encounters, only aggressiveness was significantly correlated with protrusion of the glands in the respective individuals. This strongly implies the function of the male scent as an agonistic signal, influencing the outcome of the intermale contests.     

Pillar Function in the Fiddler Crab Uca beebei (II): Competitive Courtship Signaling

Male Uca beebei court and attract females into burrows they defend on muddy sand flats in the intertidal zone on the Pacific coast of the tropical Americas. Mating, oviposition and incubation (breeding) occur underground in males' burrows. Some courting males build mud pillars (2 cm high) at the entrance of their burrow. The purpose of this field study was to assess the role of pillars in competitive courtship signaling among males. I studied the effect of pillars on female behavior by recording the responses of wandering females to courtship from males resident at burrows with and without pillars. I also caught females, released them individually in a circular arena with an equal number of empty burrows with and without pillars around its circumference, and chased the females with a simulated avian predator. Females moved to burrows of both types more often when they were courted (82%) than when they were chased (67%). Receptive females were attracted to the burrows of the males that courted them significantly more often (97%) when these burrows had pillars than when they lacked pillars (66%). However, once females entered males' burrows they were equally likely to remain, mate and breed in both types of burrows. Females also more often moved to burrows with pillars (66%) than to burrows without pillars when they ran from the simulated predator. Both male courtship displays and pillars probably provide cues females use to locate males' burrows. The visual similarity between pillars and a display courting males give immediately before they enter their burrows suggests that pillars are icons of the display. The effect of pillars on female behavior, the timing of pillar building relative to when females choose mates, and contrasts in the behavior of males that do and those that do not build pillars suggest that pillar building has evolved due to competition among males to attract females into their burrows.     

Visual and Olfactory Female-Borne Cues Evoke Male Courtship in the Aphid Parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae)

We investigated the courtship and mating behavior of the pan-tropical polyphagous endoparasitoid Aphidius colemani Viereck. The courtship and mating displays, the magnitude of male-male sexual approaches and the role of female-borne cues evoking male courtship behavior were quantified. The sequence of events leading to copulation in this parasitoid did not differ from that found for other braconids. Females refused to copulate more than once. Same-sex courtships were observed among males and their possible role in an adaptive context is discussed. Olfactory female-borne cues played a key role in eliciting the courtship responses of males. Males were attracted by freshly dead females, but not by dead females soaked in hexane, nor by visual cues from females alone. Intense male wing fanning behavior was elicited by crushed abdomens of virgin females, suggesting that the female abdomen is the source of a short-distance pheromone crucial in evoking male courtship. Further studies are required to clarify the exact nature of the chemicals involved.     

Male swordtails court with an audience in mind

Females are usually considered to be the target of male courtship behaviour. In nature, however, social interactions rarely occur without other observers; thus, it is conceivable that some male courtship behaviours are directed not towards females, but rather towards male rivals. The northern swordtail, Xiphophorus birchmanni, is a freshwater fish found in high densities in natural streams. Males court by swimming close to and in parallel with the female, raising their large sail-like dorsal fin, and quivering briefly. Here, we show that females prefer males that display small dorsal fins to those with large ones, and that males are less aggressive to other males with large dorsal fins. Male swordtails also raise their dorsal fins more frequently when courting in the presence of other males. These results suggest that, despite female avoidance of large dorsal fins, males that raise their fin during courtship benefit by intimidating potential competitors; the intended receivers of this signal are thus males, not females. Intrasexual selection can therefore offset the forces of intersexual selection, even in a courtship display.     

Court Like You Mean It: Male Siamese Fighting Fish are Less Attentive to Courting Males that Have Been Exposed to an Estrogen Mimic

Endocrine disrupting chemicals (EDCs) are ubiquitous in aquatic ecosystems where they have adverse effects on exposed organisms. In addition to causing physiological changes, EDCs often target fitness‐related behaviors such as locomotion and courtship. Ethinylestradiol (EE2) is an estrogen mimic that has been found to reduce courtship and aggression in males. However, the consequences of these reductions are not always explicitly addressed. One way in which EE2 may lead to decreased fitness occurs when males respond differently to exposed vs. unexposed conspecifics. To examine this, video playback was used to determine whether male Siamese fighting fish, Betta splendens, respond differently to exposed and unexposed males. Males were presented with four different combinations of videos of males played simultaneously: exposed swimming and unexposed swimming, exposed courting and unexposed courting, unexposed courting and unexposed courting, and exposed courting and exposed courting. Males directed more behaviors to the unexposed than the exposed courting male when presented simultaneously, likely because these unexposed males were perceived as a greater threat to mating success. Additionally, males spent more time tracking and gill flaring, two behaviors that are indicative of fight intent, when presented with two courting unexposed males. This combination could be considered the most threatening because there are two rival vigorously courting males present. These results suggest that EE2 exposure could result in exposed males receiving decreased attention from other males. However, since EE2 exposure also decreases competitive and courtship abilities, this would be far outweighed by the costs.     

Risky Courtship: Background Contrast,Ornamentation, and Display Behavior of Wolf Spiders Affect Visual Detection by Toad Predators

Males that search widely for females and perform conspicuous courtship displays run a high risk of being detected by their predators. Therefore, gains in reproductive success might be offset by increased mortality due to predation. Male brush‐legged wolf spiders (Schizocosa ocreata) with larger decorative traits (foreleg tufts) are preferred by females as mates, but are more readily detected by predators. However, predation risk may also be influenced by the interaction between components of signals and the environment in which signaling occurs. Courting male spiders were readily accepted as prey by a sympatric predator, the American toad (Anaxyrus americanus). We used video playback to tease apart the interactive effect between visual signals and the signaling environment on the ability of toads to detect courting spiders as a function of distance, background contrast, the presence or absence of male foreleg tufts, and behavioral activity. The response of toads to video sequences of male spiders was similar to their response to live male spiders. Toad response varied over distance toward spiders displayed against high contrast (sunny) vs. low contrast (shaded) backgrounds. Beyond 30 cm, more toads detected courting male spiders against light, ‘sunny’ backgrounds and detected them faster when compared to the same spider stimulus against darker, ‘shady’ backgrounds. In choice tests, toads oriented more often toward courting males with leg tufts than those without. Toad responses also varied with male spider behavior in that only videos of moving males were attacked. Latency to orient and detection by toads was significantly greater for walking males than courting males, and this effect was most evident at distances between 30 cm and 50 cm. Results supported that courting wolf spiders are at significant risk of predation by visually acute predators. Distance, background contrast, and the presence of foreleg decorations influence detection probability. Thus, the same complex visual signals that make males conspicuous and are preferred by females can make males more vulnerable as prey to toads.     

Eavesdropping and signal matching in visual courtship displays of spiders

Eavesdropping on communication is widespread among animals, e.g. bystanders observing male-male contests, female mate choice copying and predator detection of prey cues. Some animals also exhibit signal matching, e.g. overlapping of competitors' acoustic signals in aggressive interactions. Fewer studies have examined male eavesdropping on conspecific courtship, although males could increase mating success by attending to others' behaviour and displaying whenever courtship is detected. In this study, we show that field-experienced male Schizocosa ocreata wolf spiders exhibit eavesdropping and signal matching when exposed to video playback of courting male conspecifics. Male spiders had longer bouts of interaction with a courting male stimulus, and more bouts of courtship signalling during and after the presence of a male on the video screen. Rates of courtship (leg tapping) displayed by individual focal males were correlated with the rates of the video exemplar to which they were exposed. These findings suggest male wolf spiders might gain information by eavesdropping on conspecific courtship and adjust performance to match that of rivals. This represents a novel finding, as these behaviours have previously been seen primarily among vertebrates.     

Female choice for male gregariousness in a Stink bug,Megacopta punctissimum (Montandon) (Heteroptera,Plataspidae)

Adults of a stink bug,Megacopta punctissimum, form mating aggregations on their host plants, based on the gregarious habit of males. A female was released on a stem on which there was an aggregation of 2 mating pairs and 1 bachelor male. Next, the bachelor male was released on a stem on which no bugs were present, and the same female was released there. Sequences of courtship behavior were compared between them. This experiement was repeated for 41 pairs of males and females, and about half (20 cases) of these experiments were made in the reverse order. Males were the active sex in courtship, whilst females either accepted the courtship, or escaped from courting males. Females accepted courtship with a higher probability when males courted in aggregations (73%) compared to solitary conditions (22%). This was because the escape behavior of females from the males was reduced if females detected the presence of other bugs near the males. It was concluded that female choice is a selective force for gregariousness in males.     

Courtship and intersexual signaling in the parasitic waspCotesia rubecula (Hymenoptera: Braconidae)

The courtship behavior of the parasitic wasp Cotesia rubeculawas studied in a flight tunnel using standard quantitative ethological techniques. Emission of a female sex pheromone induces searching and signaling behavior in males. Males combine wing-fanning, which produces low-frequency airborne sound, with pulsing behavior, which transmits a vibrational signal through the substrate to the female and induces her receptivity. Female receptivity is indicated by a stereotyped antennal position, which may provide a visual or tactile signal to courting males. Comparison of successful and unsuccessful courtships indicated that courtship success was dependent primarily on the effective production or reception of the male pulse signal. Overall, the sequence of courtship behavior was similar to that reported for other parasitic wasps.     

The Influence of Male Body Size and Social Environment on the Mating Behavior of Phallichthys quadripunctatus (Pisces: Poeciliidae)

In some poeciliid fishes, variation in male size is accompanied by differences in mating behavior. Large males are preferred by females and perform courtship displays followed by copulatory thrusts, whereas small males perform copulatory thrusts with few or no displays. This phenomenon has been described in only a few genera and little is known about mating behavior in other poeciliids. Although Phallichthys quadripunctatus males display size dimorphism that has a genetic component, mating behavior of this species has not been documented. We conducted experiments using socially experienced and socially naive males to characterize the mating behavior of this species and to evaluate potential size-dependent differences in behavior. Males were tested with postpartum (presumably receptive) and midcycle (presumably unreceptive) females in different social environments. Whereas neither size class of P. quadripunctatus males performed courtship displays or altered behavior based on female receptivity, large males performed several reproductive behaviors more frequently than small males. This trend was repeatable and occurred in all social environments examined. Some males also attempted to mate with other males, with small males showing a greater tendency to perform this behavior than large males. The manner in which differences in reproductive activity translate into differences in reproductive success must be examined before inferring sexual selection favoring large males in P. quadripunctatus.     

Female and male interactions during courtship in Calopteryx maculata and C. dimidiata (Odonata: Calopterygidae): Influence of oviposition behaviour

Calopteryx maculata and C. dimidiata damselfly females respond to male courtship with specific displays which signal differences in their receptivity. These include a rejection (wing spreading) and an invitation (wing-flipping) display, as well as a neutral (sit still) response. There are interspecific differences in the likelihood of each female display and in male responses to these displays. C. maculata males persist in courtship irrespective of female response, while C. dimidiata males generally stop courting when the female's response is rejection or neutrality. I suggest that these differences result from interspecific differences in oviposition behaviour. Female C. maculata oviposit at the water surface, which exposes them to disturbance by males attempting to mate. Females are therefore likely to remate to secure postcopulatory guarding when changing oviposition sites and males are expected to be persistent in courtship. Female C. dimidiata submerge to oviposit, which frees them from male disturbance and means that males have less control over female access to oviposition sites. Males therefore have less influence on mating by females and are expected not to persist in courtship of non-receptive females.     

Sizing‐up the Competition: Factors Modulating Male Display Behavior During Mate Competition

When competing for mates, males of many species use cues from their rivals to evaluate their chances of success. Signaling behavior is a vital component of male–male contests and courtship, and may inform males of a rival's quality or intentions. We used eastern fence lizards (Sceloporus undulatus) to investigate how the time a male spent signaling during mate competition is influenced by his quality, his rival's quality relative to his own, and the value of a contested female. Furthermore, we examined how a male's behavioral response to a competitor's signals would be mediated by his relative quality. We simulated natural encounters by allowing two males to compete over a single female in the laboratory. We measured the time males spent performing two types of displays (pushups and shudders) and categorized male behavioral responses to rival pushup and shudder displays. Time spent signaling was not related to a male's absolute quality (body and head size, condition, and badge sizes), or his quality relative to that of his rival, although males did spend more time performing pushups when competing over females in better condition. Male behavior was also influenced by his rival's signals, such that males of relatively lower quality than their opponents were more likely to aggressively respond to rival pushups and shudders. We discuss these results with respect to the evolution and function of signaling behavior in courtship and male–male contests.