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.     

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。     

Male Competition in a Wandering Spider (Cupiennius getazi,Ctenidae)

We describe male-male competition in a wandering spider living on plants (Cupiennius getazi, Ctenidae) and discuss it within the general context of the mating system. 1. Males produce vibratory courtship signals (duration about 20 s) and competition signals (2 s). Upon exposure to female silk, males produce almost exclusively courtship signals (98%) if alone or in the presence of a female. In the presence of a rival alone, an average of 25% of a male's vibratory signals are courtship signals and 75% competition signals. In the presence of both a rival and a female, an average of 50% are courtship and 50% competition signals. Females respond to both male courtship and/or competition signals with vibratory courtship whereas males react by vibratory competition. The intensity of the reaction of both males and females is independent of the signal type. 2. Males displaying vibratory signals move slowly over the plant and repel attacks from rivals and females with extended front legs. Pairs of males interact in three ways. (i) Both males produce vibratory signals; one of them leaves the plant (53% of 90 trials). (ii) Both males vibrate, approach and touch (20%) or pounce on each other (20%). (iii) A male approaches the signalling opponent without producing vibrations and attacks him (7%). This is a conditional vibrocryptic tactic. The presence of a female incites male competition. Males do not interact with the female but approach each other (in 24% of the 26 trials “vibrocryptically”) and escalate more often (88%) and more quickly to overt fight than in the absence of a female. The male remaining on the plant approaches the female. 3. Male-male fights are ritualized. During 64 bodily contacts no male was injured. Males exposed to female silk and males using the vibrocryptic tactic were more often the winners of an interaction than males not exposed to female silk and than males vibrating while approaching their rival. The outcome of fights is not correlated with age, leg length, body weight and rate of signalling when no female is present. In contrast, body weight and leg length determine the outcome when a responding female is present, the larger male being the winner. 4. Intrasexual and intersexual interactions suggest that both male competition and female choice mechanisms may regulate sexual selection in this species.     

Honesty of agonistic signalling and effects of size and motivation asymmetry in contests

Game theoretical models predict that the main function of fighting behaviour is to assess the relative fighting ability of opponents. The sequential assessment game has often been used to investigate contests, while honest signalling theory has received much less attention. With the wolf spider Hygrolycosa rubrofasciata we investigated whether male agonistic signalling can reveal honest information about fighting ability, and how size and motivation asymmetries affect male fighting behaviour. We also determined whether male–male competition affects the courtship behaviour of the males. We found that agonistic drumming activity is an honest indicator of male fighting ability, and that relative size asymmetry and motivation to fight both contribute to the fighting ability. We also found that male–male competition decreases the courtship drumming rate of subdominant males, suggesting that male–male competition limits the opportunities for female choice. We conclude that sequential assessment and honest signalling may both be used in settling contests, and that they may be used simultaneously. Received: 10 December 1998 / Received in revised form: 23 June 1999 / Accepted: 5 July 1999     

Sexual Interference in the Sword-tailed Newt,Cynops ensicauda popei (Amphibia: Salamandridae)

This paper describes competitive interaction between males of the salamandrid Cynops ensicauda popei. The sexual behaviour of the male is influenced by the presence of a second, rival, male. Competition for access to the female and other male interactions continuously interrupt ongoing courtships. Spermatophore pick-up success is lower than in encounters involving single pairs. During triad encounters, fewer spermatophores were deposited than in dyad encounters, due to interference during the creep stage of courtship. Two basic forms of male sexual interference were distinguished: ‘lure away’ during the creeping stage, from a position that is different from the direction of creep; and ‘female mimicry’, during which the male presses his snout alternately against the courting male's tail and the female's snout. In both forms, a rival male may shove one of the courting individuals away. The repertoire of sexual behaviour patterns of Cynops ensicauda popei appears to be less complex and varied than that of most Triturus species. The courtship of Cynops places less emphasis on display behaviour with tail and body, and a stronger emphasis on the creeping stage, where the male carefully leads the responsive female over a series of spermatophores, but during which rival males may interfere in a variety of ways.     

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 fish deceive competitors about mating preferences

A fundamental question in animal communication is whether the information provided is honest or deceptive [1, 2]. This problem has received much attention, both in theoretical [1, 3] and experimental [4] work. Here we show that male Atlantic mollies (Poecilia mexicana), when observed during mate choice by another male, reduce their mating activity and no longer prefer mating with one of two females presented, which can be interpreted as an attempt to avoid unintended interception of information by the rival male. Most importantly, focal males directed their first sexual interaction (after they were presented with the rival male) toward the initially nonpreferred female, suggesting that males deceive other males about their mating preferences. Deception by the choosing male may be an adaptation to avoid sperm competition, because surrounding males may use public information and copy the focal male's mate choice.     

The Haremic Mating System and Mate Choice in the Wide-Eyed Flounder, Bothus podas

The social structure and reproductive behaviour of the wide-eyed flounder, Bothus podas, was studied in the coastal waters around the Azorean Islands. Both sexes are territorial throughout the year. Adult males defend large territories, which include several smaller female territories. Intraspecific agonistic behaviour was frequent and differed between sexes: males were more aggressive towards other males, while females were only aggressive towards each other and juveniles. During the reproductive season and only at dawn, territorial males court and mate successively with females in their territories, and females seem to show mating fidelity to their dominant male. Such territoriality and mating patterns indicate a haremic social system in the wide-eyed flounder. In order to identify potential factors influencing female mate choice acting on this haremic system, we examined male mating success and some of its potential correlates. We found no evidence for female preference for any of the males' physical or territory characteristics. However, courtship effort was strongly correlated with the total number of attempted and successful spawnings, indicating that females seem to mate preferentially with males that court them more vigorously. Thus, our data suggest that courtship plays an important role in determining male mating success in the wide-eyed flounder and, that it may possibly serve as an honest indicator of male `quality' for female choice.     

Inbreeding depression and male-mating behavior inDrosophila melanogaster

There have been relatively few studies designed to investigate the effects of inbreeding on behavioral traits. To study this phenomenon, five experimental lines ofDrosophila melanogaster made isogenic for chromosome 2 were evaluated for their male-mating ability and, subsequently, male courtship behavior. All lines showed significant reductions in overall mating ability, and males from all of these lines displayed impaired mating behavior, with two lines displaying particularly aberrant courtship patterns. Line 16 displayed an inability to successfully initiate copulation following successful courtship, while line 17 displayed significant reduction in locomotor activity, resulting in virtually no successful courtship or copulatory activity. The implications of these findings for competitive mating ability in wildDrosophila populations are presented. Further, the importance of mating success as a fitness component in the management of potentially highly inbred populations of endangered species is discussed.     

Courtship Display in a Natural Population of Crested Newts,Triturus cristatus

Field observations of courtship displays in a natural population of crested newts, Triturus cristatus, are described. Males were observed both courting females and displaying to other males, and male: male interactions were as frequent as courtships. Many courtships were also interrupted by intruding males, and courtship success was less than 7%. A comparison is made with aquaria studies, which shows that the presence of more individuals in the field, where newts aggregate in leks when breeding, is influencing male behaviour. On the other hand, the different features of the displays observed in the field did not differ to any major extent from behaviour patterns observed in aquaria studies.     

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.     

The African cichlid fish Astatotilapia burtoni uses acoustic communication for reproduction: sound production, hearing, and behavioral significance

Sexual reproduction in all animals depends on effective communication between signalers and receivers. Many fish species, especially the African cichlids, are well known for their bright coloration and the importance of visual signaling during courtship and mate choice, but little is known about what role acoustic communication plays during mating and how it contributes to sexual selection in this phenotypically diverse group of vertebrates. Here we examined acoustic communication during reproduction in the social cichlid fish, Astatotilapia burtoni. We characterized the sounds and associated behaviors produced by dominant males during courtship, tested for differences in hearing ability associated with female reproductive state and male social status, and then tested the hypothesis that female mate preference is influenced by male sound production. We show that dominant males produce intentional courtship sounds in close proximity to females, and that sounds are spectrally similar to their hearing abilities. Females were 2-5-fold more sensitive to low frequency sounds in the spectral range of male courtship sounds when they were sexually-receptive compared to during the mouthbrooding parental phase. Hearing thresholds were also negatively correlated with circulating sex-steroid levels in females but positively correlated in males, suggesting a potential role for steroids in reproductive-state auditory plasticity. Behavioral experiments showed that receptive females preferred to affiliate with males that were associated with playback of courtship sounds compared to noise controls, indicating that acoustic information is likely important for female mate choice. These data show for the first time in a Tanganyikan cichlid that acoustic communication is important during reproduction as part of a multimodal signaling repertoire, and that perception of auditory information changes depending on the animal's internal physiological state. Our results highlight the importance of examining non-visual sensory modalities as potential substrates for sexual selection contributing to the incredible phenotypic diversity of African cichlid fishes.     

Interactions between behavior and plasma steroids within the scramble mating system of the promiscuous green turtle, Chelonia mydas.

We measured plasma androgen (combined testosterone and 5alpha-dihydrotestosterone) (A) and corticosterone (B) in the promiscuous green turtle (Chelonia mydas) during courtship in the southern Great Barrier Reef. This study examined if reproductive behaviors and intermale aggression induced behavioral androgen and adrenocortical responses in reproductively active male and female green turtles. Associations between reproductive behavior and plasma steroids were investigated in green turtles across the population and within individuals. Levels across a range of both asocial and social behaviors were compared including (a) free swimming behavior; (b) initial courtship interactions; (c) mounted behavior (male and female turtles involved in copulatory activities); (d) intermale aggression (rival males that physically competed with another male turtle or mounted males recipient to these aggressive interactions); and (e) extensive courtship damage (male turtles that had accumulated excessive courtship damage from rival males). Behavioral androgen responses were detected in male turtles, in that plasma A was observed to increase with both attendant and mounted behavior. Male turtles who had been subjected to intermale aggression or who had accumulated severe courtship damage exhibited significantly lower plasma A than their respective controls. No pronounced adrenocortical response was observed after either intermale aggression or accumulation of extensive courtship damage. Female turtles exhibited a significant increase in plasma B during swimming versus mounted behavior, but no change in plasma A. We discuss our results in terms of how scramble polygamy might influence behavioral androgen interactions differently from more typical combative and territorial forms of male polygamy.     

Social context influences aggressive and courtship behavior in a cichlid fish

Social interactions require knowledge of the environment and status of others, which can be acquired indirectly by observing the behavior of others. When being observed, animals can also alter their signals based on who is watching. Here we observed how male cichlid fish (Astatotilapia burtoni) behave when being watched in two different contexts. In the first, we show that aggressive and courtship behaviors displayed by subordinate males depends critically on whether dominant males can see them, and in the second, we manipulated who was watching aggressive interactions and showed that dominant males will change their behavior depending on audience composition. In both cases, when a more dominant individual is out of view and the audience consists of more subordinate individuals, those males signal key social information to females by displaying courtship and dominant behaviors. In contrast, when a dominant male is present, males cease both aggression and courtship. These data suggest that males are keenly aware of their social environment and modulate their aggressive and courtship behaviors strategically for reproductive and social advantage.     

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.     

Courtship rate signals fertility in an externally fertilizing fish

Sperm limitation is widespread across many animal species. Several mechanisms of sperm allocation have been proposed, including optimal allocation according to clutch size and equal allocation across females. However, considerably less effort has been directed at investigating the behavioural signals associated with sperm limitation in males, which may include mating rate and the intensity of courtship. We investigated whether multiple successive spawnings affect individual male fertilization success, mating rates and courtship rates in Japanese medaka (Oryzias latipes). Across an average of 17 spawning events per male, fertilization success decreased from 83.7 per cent for the first spawning to 40 per cent for the last spawning while courtship rate decreased from 3.4 to 1.5 min⁻¹. Females appeared to respond to male sperm depletion by reducing clutch size. Our results suggest that male Japanese medaka are sperm-limited, and that courtship rate may be an honest indication of fertilization ability.     

Male singing behaviour and female presence in the territory in whitethroats Sylvia communis

Unmated male songbirds usually change their vocal behaviour when females enter their territories. Either the males court the females by changing the rate or pattern with which their normal long-ranging full songs are emitted, or they shift to special displays and long- or short-ranging vocalisations. In this study we quantified how female presence and behaviour affect the singing behaviour of male whitethroats. In the presence of a female the male frequently performed song flights, maybe to locate the female before it was courted, with sequences of diving-song displays. The courtship was interrupted by periods of perch songs. Female dscharp calls and short movements made the males initiate or resume courtship, whereas short horizontal jumps made the males intensify their courtship. Overall, the males changed their dual-function song activity in females' presence by emitting fewer perch songs and more flight songs. The quiet diving songs were only emitted during direct courtship of a female. The song types emitted immediately before, during, and after courtship are all highly variable, thus allowing for a quick assessment of the male's song repertoire. The courtship was also interrupted by periods of male woid calling, a call that is known to have a deterring effect on rival males. Bouts of woid calls were usually followed by song flights, again probably to locate the female that might have moved out of sight, or maybe to locate potential rival intruders. The latter was supported by an increased intrusion rate during female presence. Communicated by P. McGregor     

Aggression versus courtship in threespine sticklebacks and the role of habituation to neighbours

Interaction of courtship and territorial aggression in male threespine sticklebacks, Gasterosteus aculeatus, was investigated by presenting dummy females to subjects nesting alone (solitary situation) and in view of males nesting in adjacent tanks (rival situation). During dummy presentation subjects engaged in more courtship and nest activity when solitary than when in the rival situation. Behaviour of subjects in the latter situation was dominated by threats and attempts to bite rivals during dummy presentation. Thus, rivals can interfere with another male's courtship by competing for the time during which he could court a female or by eliciting in him an aggressive state that is incompatible with sexual behaviour. Subjects in the rival situation gradually decreased the time spent with rivals but increased the time spent courting the dummy and tending the nest during presentations. This decrease in aggression towards neighbouring males is presumed to result from habituation. Thus, habituation can play an important role in mitigating the aggressive response to familiar rivals, allowing males to devote more time and energy to courtship and nest activities while still forming breeding aggregations in which members may mutually benefit.     

Courtship as an honest indicator of male parental quality in the bicolor damselfish, Stegastes partitus

Previous work on the bicolor damselfish, a species with exclusivemale parental care of eggs, suggested that female mate choicewas based on male characteristics. The aims of this study wereto determine whether females discriminate among potential mateson the basis of courtship and, if so, to determine whether courtshipserves as an indicator of male parental quality. Observationsmade over two reproductive cycles showed that courtship ratesand mating success of individual males are positively correlatedand that males begin courting several days before females beginlaying eggs. Experimental manipulations showed that a male'scourtship rate is indicative of the subsequent egg survivalfrom his nest. We suggest that observed differences betweenmales in their courtship rates and parental ability may be aresult of differences in their energy reserves. These resultsdemonstrate the operation of honest advertising and lend supportto adaptive models of sexual selection. [Behav Ecol 1991;2:295–300]