Me against who? Male guppies adjust mating behaviour according to their rival’s presence and attractiveness

Sexual selection theory suggests that males need to constantly reappraise their mating decisions to take account of the presence and the phenotypes of their rivals. Here we examine this expectation by asking: (i) If the presence of a rival influences male mating behaviour; (ii) How important is the attractiveness of the rival (absolute attractiveness) in shaping male behaviour; and (iii) How does a male's attractiveness in comparison to his rival (relative attractiveness) influence a male's mating decisions. Using the Trinidadian guppy, a species in which female mate choice (based on males’ attractive traits) plays an important role in male mating outcomes, we recorded the frequency of courtship displays and unsolicited attempts by focal males. First, we quantified focal male mating behaviour with and without a rival. Since the probability of a successful mating is, on average, halved by the presence of a rival, we predicted that under competition the focal male would invest more in less costly mating tactic—unsolicited attempts. Second, we examined how the rival's standard length and area of orange coloration mediated focal male mating behaviour. We found that rival presence influenced how focal males responded to females in terms of both mating tactics. However, the rival attractiveness elicited changes only in male courtship display. Focal males increased courtship display rate if his rival was small or if possessed large amounts of orange, regardless of considering rival absolute or relative attractiveness. Our results show that males invest in the costlier mating tactic when there is no rival or in the presence of a smaller rival. Interestingly, they make a similar investment in the presence of an attractive orange rival. Overall, this study highlights the importance of fine‐grained male decisions in mating encounters and shows that mating tactics are differentially shaped by multiple competition risk cues.     

Male Siamese Fighting Fish, Betta splendens, Increase Rather than Conceal Courtship Behavior when a Rival is Present

The impact of social environment on mating success is especially pronounced in species where both intraspecific and interspecific selection influence reproduction, such as the Siamese fighting fish. Males alter male–male interactions when either a male or female audience is present, but how males change their behavior toward a female when a rival male is present is unknown. This study addresses whether males alter their behavior toward a female in a way that would prevent a rival male from interrupting courtship. The behavior of male Siamese fighting fish toward a dummy female was examined under various degrees of visual cover, both in the presence and absence of a rival male, to investigate whether males use concealment provided by the structural environment to their advantage. While males did not use barriers to conceal courtship as hypothesized, males altered their behavior by increasing courtship and monitoring their nest when a rival was visible. This increase in courtship is in contrast to most studies on courtship in the presence of a rival that find a reduction in courtship behavior. Males spent more time opercular gill flaring when no barriers were present, suggesting that males may be trying to court the female and communicate to the rival simultaneously. There was also a trend for aggression toward the female and the rival to decrease as screen length increased. Thus, males compensate for the presence of a rival by adjusting their courtship and aggressive behaviors, which could have important implications for courtship success.     

The role of signals of different modalities in initiating vibratory communication in Nezara viridula

Signals of different modalities are involved in the behaviour of the green stink bug, Nezara viridula (L.) (Pentatomidae, Heteroptera). Long range attraction is mediated by male pheromones, resulting in aggregation of bugs on the same plant where vibratory signals, vision and various chemical signals become important. Both males and females sing spontaneously. When both are on the plant, males start vibratory communication as often as females. Females induce the exchange of vibratory signals spontaneously or triggered by the male pheromone while males initiate the duet either spontaneously or after seeing the female. Males and females sing spontaneously and respond to signals of different modalities more often in the daylight than in the dark. Long lasting autonomous emission of the female calling song is present when triggered by the male pheromone and males respond to female calling predominantly by the emission of the courtship song.     

Vibratory Communication in the Jumping Spider Phidippus clarus: Substrate‐borne Courtship Signals are Important for Male Mating Success

Recently, work has shown that multimodal communication is common throughout the animal kingdom but the function of multimodal signals is still poorly understood. Phidippus clarus are jumping spiders in which males produce multimodal (visual and vibrational) signals in both male–male (aggressive) and male–female (courtship) contexts. The P. clarus mating system is complex, with sex ratios and the level of male competition changing over the course of the breeding season. Vibrational signal components have been shown to function in male aggressive contests but their role in courtship has not been investigated. Here, we performed an experiment to test the role of vibrational signaling in courtship by observing mating success for males that were experimentally muted. We show that vibratory courtship signals, and in particular signaling rate, is an important component of mating success and potentially a target of female choice. While the ability to produce vibratory signals significantly increased mating success, some muted males were still able to successfully mate. In these trials, signaling rate also predicted mating success suggesting that redundant signal components may compensate for errors and perturbations in signal transmission or that vibratory signals function to enhance the efficacy of visual signals.     

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 mating status affects male mating tactic expression in the wolf spider Rabidosa punctulata

Males and females have conflicting interests on the frequency and outcomes of mating interactions. Males maximize their fitness by mating with as many females as possible, whereas choosy females often reduce receptivity following copulation. Alternative male mating tactics can be adaptive in their expression to a variety of mating contexts, including interactions with a relatively unreceptive mated female. Male Rabidosa punctulata wolf spiders can adopt distinctive mating tactics when interacting with a female, a complex courtship display, and/or a more coercive direct mount tactic that often involves grappling with females for copulation. In this study, we set up female mating treatments with initial trials and then paired mated and unmated females with males to observe both female remating frequencies and the male mating tactics used during the interactions. Males adopted different mating tactics depending on the mating status of the female they were paired with. Males were more likely to adopt a direct mount tactic with already-mated females and courtship with unmated females. Already-mated females were considerably less receptive to males during experimental trials, although they did remate 34% of the time, the majority of which were with males using a direct mount tactic. Whereas males adjusting to these contextual cues were able to gain more copulations, the observation of multiple mating in female R. punctulata introduces the potential for sperm competition. We discuss this sexual conflict in terms of the fitness consequences of these mating outcomes for both males and females.     

Female competition for availability of males in insects: the Nezara viridula (Linnaeus, 1758) model

Multimodal communication in solitary stinkbugs enables them to meet, mate and copulate. Many plant‐dwelling species exchange information during the calling phase of mating behavior using substrate‐borne vibratory signals. A female‐biased gender ratio induces rivalry and competition for a sexual partner. Female competition for males, first described among Heteroptera in three stinkbug species, revealed species specific differences and opened the question of plasticity in individually emitted temporal and frequency signal characteristics during calling and rival alternation. To address this question and gain an insight into the mechanisms underlying stinkbug female rivalry, we compared the characteristics of alternated signals in the southern green stinkbug Nezara viridula (Linnaeus, 1758) (Hemiptera: Pentatomidae). Compared to male rivalry, female rivalry is more complex, lasts longer and runs through successive phases by a combination of different song types. The male pheromone triggers alternation between females, producing song pulses that occasionally overlap each other. One female initiates the rivalry by changing individual pulses into pulse trains of three different types. The competing female alternates with pulses of changed temporal characteristics at lower levels of rivalry and by varying the frequency characteristics of pulse trains at higher levels. During female rivalry, the male either stops responding or occasionally emits calling and courtship signals in response to the female that has produced signals of steady temporal characteristics. Female rivalry shows complex and species specific patterns of information exchange at different levels with a broad‐range variation of temporal and frequency characteristics of, until now, unidentified vibratory emissions.     

Female sex pheromone of a wandering spider (Cupiennius salei): identification and sensory reception

Females of the wandering spider Cupiennius salei attach a sex pheromone to their dragline. Males encountering the female dragline examine the silk thread with their pedipalps and then typically initiate reciprocal vibratory courtship with the sexual partner. The female pheromone was identified as (S)-1,1'-dimethyl citrate. The male pheromone receptive sensory cells are located in tip pore sensilla and respond to touching the sensillum tip with female silk or pieces of filter paper containing the synthetic pheromone.     

Male Competition over Access to Females in a Spider with Last-Male Sperm Precedence

Agonistic behaviour between male cellar spiders (Pholcus phalangioides) was investigated to test whether (1) size difference determines which male achieves access to the female, (2) males are able to monopolize access to the female until egg laying and whether (3) female resource value increases before egg laying because of last‐male sperm precedence. We further investigated whether (4) there is variation in time and energy spent on courtship and copulation depending on the degree of sperm competition, i.e. with or without rival present. In three experimental settings we introduced two males of either different or similar sizes, or a single male to a female. The mating units were constantly video‐observed until the females produced their first egg sac. Experience, ownership and female resource value in terms of body size was controlled. Our results show that larger males achieve almost exclusive access to females. Size symmetrical settings resulted in increased fighting activity and duration but dominance did not influence mating success. If copulations were disturbed by the rival male, copulations were terminated earlier in symmetrical settings compared with asymmetrical settings. In 94.8% of trials only one copulation took place, suggesting that the copulating male successfully monopolized access to the female. Males confronted with a rival copulated longer but courted significantly shorter than lone males. Although the last male to copulate sires 88% of the offspring in P. phalangioides, neither fighting nor courtship activity increased before the female laid a batch of eggs. This suggests that males have no indication of the timing of oviposition.     

Spider Males Adjust Mate Choice but Not Sperm Allocation to Cues of a Rival

Spatial and temporal variation in ecological parameters selects for plastic responses to prevailing conditions. Males of web spiders have been shown to adjust developmental decisions to cues that relate to the degree of competition from other males. Here, we explore experimentally whether males of the spider Nephila senegalensis base behavioural decisions in the context of mate choice and sperm allocation to the presence of cues of a rival and to their own competitive dominance. Large and small males were offered a simultaneous choice between two penultimate instar females that varied in quality and in whether they were previously visited by a rival male. Large and small males avoided webs visited by a previous male, and this preference overrode differences in female quality. In a second experiment, males were assigned to copulate with a virgin female whose web was either previously visited by a rival male or not. We found substantial variation in male sperm allocation, but this variation was not related to our treatment. Our experiments demonstrate that males notice silk cues left behind by rival males on a female’s web and that they can utilize these cues in relation to decisions over whether to visit a web, but not in relation to sperm allocation.     

Mechanism of mate detection in parasitoid wasps: sound and vibratory cues change with the developmental progress of future mates inside host pupal cases

Insects including parasitoid wasps use acoustic and vibratory signals in the context of sexual communication, mate recognition, courtship and mating. Males of the parasitoid wasp Pimpla disparis Viereck (Hymenoptera: Ichneumonidae) detect insect host pupae parasitized by a conspecific female, learn their location, visit them repeatedly and remain on or near them when the prospective mate nears emergence. In the present study, the acoustic and vibratory cues that males exploit to detect the presence and track the developmental progress of a future mate inside a host pupal case are investigated. Responses are acquired from developing parasitoids (DePa) by airborne sound and laser Doppler vibrometer recordings, after gently stimulating each of 20 wax moth host pupae with a paintbrush on days 1–23 post parasitism. Sound and vibratory cues produced by DePa are detectable from day 7 onward and relate mostly to spinning movements. Parameters of sound and vibratory cues (amplitude, dominant frequency, upper limit of frequency band) change significantly over time and thus could ‘inform’ a visiting adult male about the stage of development of DePa. Adult males antennating a parasitized pupa and flying around it also induce vibrations, which in turn may inform DePa about the presence of a male. There is no experimental evidence for true signalling and rapid information exchange between DePa and adult males. Delaying reply signals may help DePa avoid attacks by illicit receivers of such signals, including female (hyper)parasitoids and invertebrate predators.     

Male–male interactions and male mating success in the leafhopper Aphrodes makarovi

In mating systems based on substrate‐borne vibrations, sexual communication often involves a reciprocal exchange of species‐ and sex‐specific vibrational signals and male is searching for a stationary female. In the leafhopper Aphrodes makarovi, female reply is essential for successful location of the female and its variable duration directly affects male's costs associated with signalling and searching. We studied male and female behaviour in a trio situation (two males and one female), and our results show that male–male competition had important effects on male mating success. Females replied equally to advertisement calls emitted by the winning and losing males and mated with the first male that located them, regardless of his investment in calling effort. Males eavesdropped to male–female duet maintained by the rival, and the winners were better at exploiting female replies to the rival's advertisement calls by silently approaching the female. To interfere with the ongoing male–female duet, males also emitted masking signals overlapping the latter part of the female reply. More overlapped female replies were registered in response to the losers and masking signals most likely delay the rival in reaching the female. Our study shows that a comprehensive understanding of male mating success and female preferences in vibrational duetting systems requires also investigations in more complex settings that more realistically represent the situation in nature.     

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.     

Female responses to isolated signals from multimodal male courtship displays in the wolf spider genus Schizocosa (Araneae: Lycosidae)

Male wolf spiders within the genus Schizocosa display considerable variation in foreleg ornamentation as well as in courtship communication. Multiple modes of male signalling have evolved in a number of species. Divergence in courtship signals among species within this genus may be directly associated with variation in the sensory sensitivities of conspecific females. We isolated the visual and vibratory courtship cues of four species of Schizocosa and recorded conspecific female receptivity to each isolated cue. We also examined female receptivity to complete multimodal courtship signals. We found that the sensory sensitivities of conspecific females were associated with the predominant modes of male courtship communication. Species in which females use mostly stridulatory cues in assessing conspecific males tended to have stridulation-based male courtship displays (S. duplex and S. uetzi) while the opposite was true for species in which females used more visual cues in male assessment (S. stridulans and S. crassipes). This study suggests coevolution between male signal design and female sensory design. We discuss possible scenarios that could be driving this coevolution, including hypotheses of sensory bias and environmental constraints. Copyright 1999 The Association for the Study of Animal Behaviour.     

RESEARCH PAPER: Multiple Sexual Ornamentation Signals Male Quality and Predicts Female Preference in Minnows

Sexual ornamentation often consists of multiple components. Different sexual signals may indicate different aspects of mate quality or reflect quality in different time scales. On the other hand, same signals can have a dual function and are used both in male–male competition and courtship. Many fish species are capable of rapidly altering their colouration (ephemeral colour changes), but this capability is usually ignored in sexual selection studies. Here, we used experimentally manipulated social environments to study the ephemeral colour changes in multicomponent sexual signals of male minnows (Phoxinus phoxinus) during male–male competition and female choice. We found that the dominant males courted the females more actively and had redder and/or darker skin colouration than the subordinate males. Furthermore, darkness difference between subordinate and dominant males increased in the presence of female, which suggests that the male–male competition may increase the honesty of signalling and thus facilitate female choice. In support of this hypothesis, females had a strong behavioural preference towards the more colourful males, which may indicate female choice. As colourful males often had a higher social status than paler individuals, it is possible that females base their preference on male status, not only the colouration per se. In any case, our results suggest that sexual ornamentation of male minnows may signal status, courting activity and superior quality of the males and that these signals may have a dual function in both male–male competition and female choice. Females preferred different ornamental traits (dark and red colour patterns) relatively equally, indicating that mate choice is based on multiple cues.     

Vibrational directionality in the southern green stink bug, Nezara viridula (L.), is mediated by female song

We tested the hypothesis that male southern green stink bugs, Nezara viridula (L.), use substrate-borne songs to locate females. We recorded the responses of bugs on plants to the vibrations caused by a prerecorded female song and by an artificial sound. The female song caused males to walk, to respond with the calling and courtship songs and to approach the source of the song with characteristic search behaviour at junctions between branches on the plants. At a junction, a searching male stopped, stretched his legs and antennae and compared the vibratory signals on the two branches, with different combinations of legs and antennae. The males then left the junction and approached the source of the vibration. Males located the loudspeaker significantly more frequently in the presence than in the absence of vibratory stimuli on cyperus, Cyperus alternifolius L., and beans, Phaseolus vulgaris L. Vibrational directionality was also elicited by artificial pure tones whose spectral and temporal parameters were similar to those of natural female song. Females showed no reaction to vibratory stimulation and no vibrational directionality. We discuss possible mechanisms underlying vibrational directionality in the light of expected signal changes during transmission through plants. Copyright 1999 The Association for the Study of Animal Behaviour.     

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.     

Social context-dependent modification of courtship behaviour in Drosophila prolongata

Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform ‘leg vibration’, in which a male vibrates the female''s body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to ‘rubbing’, which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration.     

The Effect of Male Competition on the Courtship Song of Drosophila melanogaster

The courtship song of Drosophila has been extensively used as a model system for studies of sexual selection and species recognition. Traditionally, the courtship song has been recorded from males placed individually with a female. However, under natural conditions females are exposed to multiple courting males, and the effect of their joint signal on mate recognition by the female is not yet understood. Here, we recorded the courtship behavior of D. melanogaster males singing either individually to a female lpar;1:1) or in the presence of an additional male lpar;2:1). We compared the structure of the male song in the two experimental designs. Our results show that when two males courted a female their songs could overlap each other. Males produced a significantly different signal in the presence of competition; the duration of each song component was significantly shorter and the rate of singing was markedly lower. The present study demonstrates that male competition can dramatically alter the acoustic signal detected by the female.     

Acoustical communication and the mating system of the Australian whistling moth Hecatesia exultans (Noctuidae: Agaristinae)

Males of the Australian whistling moth Hecatesia exultans produce ultrasonic acoustical signals while perched on low vegetation. Some males call more or less continuously for several hours during midday with individuals occupying the same general calling area for up to several weeks. The nearest neighbour of calling males is typically 15 to 25m distant, at the outer edge of the estimated range at which neighbours can detect each other's ultrasonic signals. Calling male intruders occasionally enter an occupied territory, resulting in aerial clashes with nearly continuous signalling by both combatants. Males respond to playback of taped signals by flying toward the speaker and sometimes by calling while perched on or near the speaker. Females sometimes visit calling males, with copulation following very soon after the female alights on vegetation near the male's perch. Males increase the rate of sound production by about 11% when presented with moving pinned specimens or paper models of conspecifics. These observations and experiments indicate that males use ultrasound as long-distance communication signals designed to attract sexually receptive females and to establish territorial residency in competition with other males.