Mate-guarding Behaviour Research Articles

Analysis of neural mechanism for mate-guarding behavior, using small fish medaka

Analysis of neural mechanism for mate-guarding behavior, using small fish medaka

Wingless ant males adjust mate-guarding behaviour to the competitive situation in the nest

We investigated whether wingless sexuals of the ant Hypoponera opacior adjust mate-guarding behaviour to the level of competition in the nest. Males mate with young nestmate females shortly before these emerge from the cocoon. Aggressive interactions among adult males have never been observed, but males embrace and guard the cocoons of their mating partners for up to 2 days. In laboratory experiments, the duration of pupal guarding increased with the number of adult males in the nest, but decreased with an increasing number of mating partners per male. These findings demonstrate that males are aware of the competitive situation in the nest and adjust their mating behaviour in an adaptive manner. Males also guarded and attempted to copulate with sterile worker and male pupae. These misdirected behaviours might be the result of identification errors, as we found that the cuticular hydrocarbon profiles of young individuals of the different castes were very similar. Copulatory behaviour towards sterile workers is certainly maladaptive, whereas interactions with young males may provide a fitness benefit: We found a high mortality rate of young males that were embraced and guarded by adult males. Adult male–male pupae interactions predominantly occurred when only a single male was present in the nest. In addition, single-male nests were found at unusually high frequencies. These findings suggest that wingless males try to kill their pupal rivals through embracing when there are few adult competitors in the nest, but switch to mate-guarding behaviour when intramale competition is high.

Mate guarding behavior in clam shrimp: the influence of mating system on intersexual conflict

Mate guarding is a male strategy to gain access to receptive females but often results in antagonistic interactions between the sexes because of different costs/ benefits of guarding. In addition to social, morphological, and physiological parameters, the type of mating system should also affect the strength of the conflict and thus the guarding duration. Specifically, when compared to females, self-compatible hermaphrodites might have reduced bene- fits of outcrossing. We investigated mate guarding in dioecious (co-presence of females and males) and andro- dioecious (co-presence of hermaphrodites and males) branchiopod crustaceans. Both sexes in androdioecious systems should shift their guarding times to lower values relative to dioecious systems because (1) androdioecious males are present in lower percentages than dioecious males and thus encounter rates with receptive mates are relatively greater for them; and (2) hermaphrodites should have low incentive to incur high costs of mate guarding, having the alternative of self-fertilization, and thus should be highly eager to resist. While females preferred short guarding times, when allowed to control the guarding duration (males tethered), dioecious males did not increase their guarding duration when females (treated with muscular relaxant) could not resist, in contrast to what has previously been found for androdioecious males. This indicates that hermaphrodites are more willing to resist mate guarding than females. The among-species comparisons supported our hypotheses: compromised guarding times were signif- icantly lower in androdioecious than in dioecious species. The introduction of ap arameter (mating system) not previously investigated in mate guarding models resulted in a powerful test of mate guarding theory, adding a valuable contribution to our understanding of intersexual conflict.

Size-assortative pairing in Gammarus pulex (Crustacea: Amphipoda): a test of the prudent choice hypothesis

Positive assortative mating is a widespread phenomenon in the animal kingdom. Several hypotheses have been proposed to explain this reproductive pattern in natural populations, but growing evidence suggests that assortative mating most often results from sexual mating preferences. Recently, condition-dependent mate choice in the face of costly competition for mates has been proposed to explain assortative mating in natural populations. Variation in competitive ability may generate variation in both the strength and the direction of mate preference, resulting in assortative mating with respect to individual quality if low-quality competitors are less choosy, or if high-quality males and females pair up first, leaving low-quality individuals to form pairs between themselves. We investigated individuals' preferences for mates on the basis of differential competitive abilities and size-dependent costs in mate-guarding behaviour in the amphipod Gammarus pulex. Our results show that the presence of an unpaired male close to a pair can induce stress that can lead to pair separation. However, no direct take-over was observed. In our series of male mate choice experiments, under low, high or simulated levels of competition, small males made similar choices. Our results suggest that the frequency of take-overs, and more generally interference competition, can be considered insufficient to induce a reduced preference for large females in this population, and is thus unlikely to explain size-assortative mating.

Female genital morphology and mating behavior of Orchestina (Arachnida: Araneae: Oonopidae)

The unusual reproductive biology of many spider species makes them compelling targets for evolutionary investigations. Mating behavior studies combined with genital morphological investigations help to understand complex spider reproductive systems and explain their function in the context of sexual selection. Oonopidae are a diverse spider family comprising a variety of species with complex internal female genitalia. Data on oonopid phylogeny are preliminary and especially studies on their mating behavior are very rare. The present investigation reports on the copulatory behavior of an Orchestina species for the first time. The female genitalia are described by means of serial semi-thin sections and scanning electron microscopy. Females of Orchestina sp. mate with multiple males. On average, copulations last between 15.4 and 23.54 min. During copulation, the spiders are in a position taken by most theraphosids and certain members of the subfamily Oonopinae: the male pushes the female back and is situated under her facing the female's sternum. Males of Orchestina sp. possibly display post-copulatory mate-guarding behavior. The female genitalia are complex. The genital opening leads into the uterus externus from which a single receptaculum emerges. The dorsal wall of the receptaculum forms a sclerite serving as muscle attachment. A sclerotized plate with attached muscles lies in the posterior wall of the uterus externus. The plate might be used to lock the uterus during copulation. The present study gives no direct evidence for cryptic female choice in Orchestina sp. but suggests that sexual selection occurs in the form of sperm competition through sperm mixing.

The effects of male mating behaviour and food provisioning on breeding success in snow buntings Plectrophenax nivalis in the high Arctic

For passerine birds breeding in the Arctic, paternal effort in parental care is necessary for successful breeding. Behavioural strategies, such as mate guarding, to ensure paternity should therefore also be common in this environment. In order to investigate the relation between such behaviour and breeding success, when controlling for the effect of environmental factors, we recorded male mate-guarding behaviour, parental effort and breeding success amongst snow buntings, Plectrophenax nivalis, in the high Arctic environment of Spitsbergen, Svalbard. Mate-guarding intensity tended to positively affect male feeding frequency per nestling in one of the study years, negatively in 1 year and without effect in the 3rd year. The negative effect in 1999 was strong, but variation in estimates of the 2 other years was high and the effect of mate guarding may be negligible in these 2 years. We assume that this pattern might be related to yearly variation in the prevalence of extra-pair young. Male food provisioning was not positively related to breeding success, but late breeders had higher breeding success than early breeders. Thus, the effect of male mate guarding is highly variable and mainly affects food provisioning rates, but the benefit for total breeding success seems to be marginal, at best.

Insect wing shape evolution: independent effects of migratory and mate guarding flight on dragonfly wings

Although, in some insect taxa, wing shape is remarkably invariant, the wings of Anisopteran dragonflies show considerable variation among genera. Because wing shape largely determines the high energetic costs of flight, it may be expected that interspecific differences are partly due to selection. In the present study, we examined the roles of long-distance migration and high-manoeuvrability mate guarding in shaping dragonfly wings, using a phylogeny-based comparative method, and geometric morphometrics to quantify wing shape. The results obtained show that migration affects the shape of both front and hind wings, and suggest that mate guarding behaviour may also have an effect, especially on the front wing. These effects on front wing shape are at least partly independent. Our findings are interesting when compared with the geographically widespread and ecologically diverse dipterans Acalyptratae (including the genus Drosophila). The wings in that group are similar in function and structure, but show strikingly low levels of interspecific variation.

Dulling the senses: the role of the antennae in mate recognition, copulation and mate guarding in decorated crickets

Antennae are important sensory organs in insects because they enable the perception of chemical and tactile cues believed to be important in sex recognition and mating in various species. To examine the role of the antennae in the mating behaviour of decorated crickets, Gryllodes sigillatus, we experimentally manipulated the chemosensory ability of males and females and altered the chemical cues present on the female cuticle. Our results suggest that males rely heavily on their antennae to recognize conspecific females, because antennectomized and chemically ablated males were less likely to produce the courtship song upon contact with a female. The chemical cues used by males to recognize females appear to be sex specific, because males courted dead females that had been stripped of their surface hydrocarbons and imbued with hydrocarbons extracted from other females, but ignored females similarly stripped of their cues and imbued with extracts derived from males. Females, in contrast, did not seem to rely on their antennae for sex recognition, because antennectomized females frequently mounted males, although they took significantly longer to do so. Males lacking antennae almost never showed mate-guarding behaviour, while males with intact antennae almost always did. Collectively, these results suggest that sensory information provided by the antennae is critical to the mating success of both male and female crickets.

Mate-guarding behavior in clam shrimp: a field approach

Precopulatory mate guarding is a complex behavior, influenced by many social and physiological factors, representing a case of intersexual conflict. Mate guarding has often been analyzed with the aid of theoretical models. In these models, it is commonly predicted that mate-guarding time is influenced by encounter rates between males and females, the contenders’ relative sizes, and the possible interaction among males (i.e., ‘‘takeovers’’: one guarding male displacing another). The factors influencing male and female guarding decisions have been measured in laboratory experiments but never under natural field conditions. In this field-based study, we observed mate-guarding couples of the clam shrimp Limnadia badia in ephemeral pools on granite rock outcrops in Western Australia. We recorded guarding duration, focusing on the factors considered important in mate-guarding models: male and female size, population density, sex ratio, operational sex ratio, and the status of female receptivity. We also estimated time budgets for males, the possibility of male takeovers, and the potential role of female resistance. We found that female receptivity stage (how close the female was to molting), small male size, and low absolute female presence are key factors in decreasing mate-guarding duration. This study adds a field dimension to manipulative laboratory projects and theoretical models of mate guarding. We were able to observe the simultaneous interactions of multiple factors in the field and to make a robust examination of the ideas of intersexual conflict during mate guarding in these crustaceans. Key words: branchiopoda, density,femaleresistance,fieldobservations,intersexualconflict,Limnadiabadia,malesize,sexratio,WesternAustralia. [BehavEcol]

Extrapair copulations are frequent but unsuccessful in a highly colonial seabird, the little auk, Alle alle

Sperm competition theory predicts that colonially breeding birds, such as many seabirds, should be exposed to high risks of sperm competition because there are many potential mating partners and severe socioecological constraints on mate-guarding behaviour. However, parentage studies have usually revealed a low frequency of extrapair paternity in colonial seabirds. Detailed studies of copulation behaviour could provide valuable insights into the causality of genetic monogamy in these species. We investigated the timing, frequency and success of extrapair and within-pair copulation attempts in the little auk, a socially monogamous and highly colonial seabird that raises only a single chick per year. We found that the majority of monitored individuals (above 60% in both sexes) engaged in extrapair copulation activities. Extrapair copulation attempts made up usually more than 10% of all copulation attempts of a particular individual but were generally unsuccessful because of female rejection behaviour. Only 2% (8/330) of all copulations with cloacal contact were extrapair copulations. Molecular parentage analysis of 64 chicks revealed only two cases of extrapair paternity, which is comparable to the proportion of successful copulations that were extrapair. We conclude that genetic monogamy seems to be maintained at a proximate level through female resistance to male extrapair copulation attempts and frequent within-pair copulations. Nevertheless, not all extrapair copulations were rejected by females, which suggests that engaging in one or a few extrapair copulations could be adaptive to females, for example as an insurance against mate infertility.

Effects of density experience on mate guarding behavior by adult male Kanzawa spider mites

In the Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae), adult males guard pre-reproductive quiescent females. I experimentally examined the effects of density experience during development and/or after adult emergence on precopulatory mate guarding behavior by T. kanzawai males. Mate guarding behavior was modified by density experience after adult emergence. When males had previously experienced high density after adult emergence (n = 71), 73.2% of them engaged in precopulatory mate guarding. In contrast, when males had previously experienced low density after adult emergence (n = 82), 61.0% of them did not guard females. Mate guarding with physical contact occurred more frequently when males had previously experienced a high density of potential rivals than when they had not, but the difference in behavior between the two groups of males was marginally not significant. Nevertheless, these results suggest overall that T. kanzawai males change mate guarding behavior in response to previously experienced density.

The less amorous Gammarus: predation risk affects mating decisions in Gammarus duebeni (Amphipoda)

We examined the trade-off between the behaviours associated with predator avoidance and mate acquisition in the mate-guarding amphipod crustacean Gammarus duebeni. We used laboratory experiments to investigate the impact of olfactory predator cues on activity, mate choice and mate-guarding behaviour of males and females. Pair formation declined under perceived risk of predation, reflecting reduced activity of both males and females and hence a reduced likelihood of encountering a mate. We also observed a reduction in the choosiness of both males and females. Under increased perceived predation risk, assessment of the female by the male was more likely to be followed by pair formation, and males showed a nonsignificant trend towards reduced discrimination in favour of large females and were less tenacious in their pair bond when they paired during exposure to predator cues. Females also showed less resistance behaviour, suggesting that both males and females trade off the costs of maximizing current reproductive success against the benefits of predator avoidance for survival and reproduction in the future. We discuss the implications of such context-dependent mating behaviours for ecological interactions between species and suggest that predators, via the effects of perceived predation risk on mate choice and mate guarding in the prey species, induce trait-mediated indirect effects with the potential to influence population dynamics and community structure.

Mate guarding and frequent in-pair copulation in humans : Concurrent or compensatory anti-cuckoldry tactics?

Cuckoldry is an adaptive problem faced by parentally investing males of socially monogamous species (e.g., humans and many avian species). Mate guarding and frequent in-pair copulation (IPC) may have evolved as anti-cuckoldry tactics in avian species and in humans. In some avian species, the tactics are used concurrently, with the result that mate guarding behaviors and IPC frequency are correlated positively. In other avian species, the tactics are compensatory, with the result that mate guarding behaviors and IPC frequency are correlated negatively. The relationship between mate guarding and IPC frequency in humans is unknown. Avian males that use these tactics concurrently share with human males an inability to guard a female partner continuously during her peak fertile period. We hypothesized, therefore, that men's mate guarding and IPC frequency function as concurrent anti-cuckoldry tactics, resulting in a positive correlation between them. Study 1 (n=305) secured men's self-reports of mate guarding and IPC frequency. Study 2 (n+367) secured women's reports of their partners' mate guarding and IPC frequency. The concurrent tactics hypothesis was supported in both studies: Men's mate guarding and IPC frequency are correlated positively, and this association is not attributable to male age, female age, relationship satisfaction, relationship length, or time that the couple spends together. The Discussion section addresses potential limitations of this research and future research directions.

NATURAL HISTORY OF GLENOGNATHA EMERTONI (ARANEAE, TETRAGNATHIDAE): MATING BEHAVIOR AND SPERM RELEASE IN A HAPLOGYNE

Glenognatha emertoni (Simon 1887) is a small haplogyne orb-weaver collected near streams and dry streambeds in southern Arizona whose habits are unknown. Field observations revealed that G. emertoni are commonly found in vegetation overhanging streams and, more rarely, under stream- side rocks. Mating pairs were observed on or near adult female webs. Males lack mate-guarding behavior and leave the female immediately after copulation. To examine mating behavior in a controlled setting, juveniles and adults were collected from the field and maintained in the lab. Matings were arranged between wild-caught adults and also between laboratory-reared virgins in order to describe mating behavior and sperm release during copulation. Unlike most other orb-weaving spiders studied, the number of sperm released and overall duration of copulation are not influenced by female mating history in G. emertoni. Male G. emertoni release equivalent numbers of sperm to virgin and non-virgin females. Given this pattern of sperm release and the lack of mate-guarding behavior by males, sperm competition should be intense in this species. Based only on the numbers of sperm released by each male in the study, doubly-mated females would be expected to produce egg sacs of mixed paternity, if all else were equal.

Delayed copulation as a means of female choice by the hermit crab Pagurus filholi

Male hermit crabs perform precopulatory mate-guarding behavior during their reproductive season. As females generally cannot reject guarding attempts by males, male guarding prevents females from inspecting and choosing other male mates. However, as guarding males are often replaced by other males through competition for females during the guarding phase, females may be able to select males by delaying their copulation. To examine the possibility of female choice by hermit crabs, we investigated whether female Pagurus filholi that were being guarded in the field were ready to copulate and spawn. We found that about 30% of females guarded in the field were ready to spawn, indicating that guarded females delayed copulation with their current male. Our results suggest that by delaying copulation females may exploit male–male competition to “choose” dominant males. However, delaying copulation reduced the spawning potential of females. Hence, there is a trade-off between waiting for the opportunity to mate with a dominant male and decreased spawning success if females exploit male–male competition.

Effects of breeding density and plumage coloration on mate guarding and cuckoldry in blue grosbeaks (Passerina caerulea)

For species in which females mate outside of the pair bond, selection should favor male mate-guarding behaviors that minimize investment in genetically unrelated offspring. Mate guarding may impose costs by diverting time and energy from activities such as foraging and seeking extra-pair copulations, so males should adjust their mate-guarding behavior according to the risk of cuckoldry. In this study, we investigated cuckoldry and mate guarding in the blue grosbeak (Passerina caerulea L., 1758), a socially monogamous, territorial songbird. Fifty-three percent of nestlings were extra-pair, and 70% of nests had at least one extra-pair fertilization. Males with dull plumage coloration were more likely to be cuckolded than males with more brightly colored plumage, but duller males did not guard their mates more. Instead, males appeared to adjust mate-guarding behavior according to the attractiveness of neighbors. Males with more brightly colored neighbors guarded their mates more intensely than males with fewer colorful neighbors. These observations suggest that in the blue grosbeak, mate guarding is a context-dependent strategy that is adjusted according to the density and ornamentation of neighboring males.

Behavioral strategies and hormonal profiles of dominant and subordinate common marmoset (Callithrix jacchus) females in wild monogamous groups

New insights into the mating systems of common marmosets suggest that they are mainly monogamous, although polygyny and polyandry occasionally occur. Long-term monitoring of wild common marmosets has shown that some reports of polygynous groups (i.e., groups that contain more than one reproducing female) in fact indicate an unbalanced reproductive output associated with extragroup copulation. In this study we describe the behavioral and hormonal profiles of common marmoset (Callithrix jacchus) females living in three wild monogamous groups (Q, PBf, and T), varying from five to 11 individuals, at Nísia Floresta field station, RN, Brazil. The mating system of the groups was previously characterized in terms of affiliative, sexual, and mate-guarding behaviors. Behavioral data were collected once a week, and fecal samples were collected at least twice a week for 10-16 months, depending on the group. A preferential allogrooming relationship was recorded between dominant males and females. Under field conditions the reproductive inhibition of subordinate females appears to be more behavioral than hormonal, since subordinate females of the three groups ovulated and two conceived during the study. In these cases, the subordinate and dominant females reproduced 1 month apart, and infanticide (one case confirmed and one suspected) appeared to be part of the reproductive strategy of dominant females. Following the infanticide, ovarian inhibition (group T) or emigration and return to the natal group (group PBf) were observed. In the third group (Q) the subordinate female showed hormonal profiles compatible with pregnancy, but no infants were seen. These findings reflect the different alternatives that wild subordinate common marmoset females use to reproduce.

Mate guarding, male attractiveness, and paternity under social monogamy

Socially monogamous species vary widely in the frequency of extrapair offspring, but this is usually discussed assuming that females are free to express mate choice. Using game-theory modeling, we investigate the evolution of male mate guarding, and the relationship between paternity and mate-guarding intensity. We show that the relationship between evolutionarily stable mate-guarding behavior and the risk of cuckoldry can be complicated and nonlinear. Because male fitness accumulates both through paternity at his own nest and through his paternity elsewhere, males evolve to guard little either if females are very faithful or if they are very unfaithful. Attractive males are usually expected to guard less than unattractive males, but within-pair paternity may correlate either positively or negatively with the number of extrapair offspring fertilized by a male. Negative correlations, whereby attractive males are cuckolded more, become more likely if the reason behind female extrapair behavior applies to most females (e.g., fertility insurance) rather than the subset mated to unattractive males (e.g., when females seek “good genes”) and if mate guarding is efficient in controlling female behavior. We discuss the current state of empirical knowledge with respect to these findings.

Transient sexual mimicry leads to fertilization

Sexual mimicry among animals is widespread, but does it impart a fertilization advantage in the widely accepted 'sneak-guard' model of sperm competition? Here we describe field results in which a dramatic facultative switch in sexual phenotype by sneaker-male cuttlefish leads to immediate fertilization success, even in the presence of the consort male. These results are surprising, given the high rate at which females reject copulation attempts by males, the strong mate-guarding behaviour of consort males, and the high level of sperm competition in this complex mating system.

Precopulatory mate guarding by the male green chafer, Anomala albopilosa sakishimana Nomura (Coleoptera: Scarabaeidae)

Mating behavior of the green chafer Anomala albopilosa sakishimana Nomura (Coleoptera: Scarabaeidae) was observed in Miyako Island, southwestern Japan from 28 to 29 May 2003. Females and males were present on patches of the beach naupaka, Scaevola sericea Vahl, throughout this time and showed clumped distribution within the patches. Males were observed to mount the backs of females for several hours during a day and successfully defend females from intruding males. Copulations took place only from 19:00 to 20:00 (JST) and most frequently at 19:40 (light intensity: 24 lx). Mean copulation duration was 18.1±2.6 min (mean±SD, N=16). After mating, both sexes remained on the same leaf to feed. When females guarded by males were collected before mating time and subsequently reared in the laboratory, about 65% (11/17) laid fertilized eggs. This indicated that most of the females mounted by males are not virgin. In laboratory observations, several females mated more than once on different days, indicating A. a. sakishimana females are polyandrous. Since mounted males successfully defended the females from intruding males in the laboratory, long-lasting mounts appear to comprise precopulatory mate-guarding behavior. This is the first record of precopulatory mate guarding in scarab beetles.