Nonindependent mating in a coral reef damselfish: evidence of mate choice copying in the wild

Theoretical and experimental studies have shown that mate choicecopying is a viable mating strategy under certain conditions.Copying experiments in fish have been conducted primarily inthe laboratory, except for one study conducted in the fieldunder artificial conditions. We investigated whether in a wildpopulation of the coral reef whitebelly damselfish (Amblyglyphidodonleucogaster) females copy the choice of other females. Femalespreferentially spawn with males that have recently mated. Todetermine if the presence of new eggs in the nest was the reasonfemales chose mates or whether females were mate choice copying,we conducted egg-switching experiments. Eggs from males thatrecently mated were donated to males that had no eggs. If femalesare mate choice copying, then donor males with no eggs in thenest should continue to receive additional eggs. If femalesare using the presence of new eggs as the criterion for matechoice, then foster males with new eggs should receive additionaleggs. We found that donor males received new eggs significantlymore often than expected. More females mated with donor malesthan foster males. Furthermore, females preferentially choseto mate with males whom they had seen mating with another female.Females appear to remember the mate choice of other femalesand choose to mate with those same males even after 1 day. Theseresults suggest that females may be copying the mating decisionof other females rather than choosing males based on the presenceof new eggs in the nest.     

Female remating propensity contingent on sexual cannibalism in sagebrush crickets, Cyphoderris strepitans: a mechanism of cryptic female choice

Male sagebrush crickets (Cyphoderris strepitans) permit femalesto engage in an unusual form of sexual cannibalism during copulation:females feed on males' fleshy hind wings and ingest hemolymphoozing from the wounds they inflict. These wounds are not fatal,and normally only a portion of the hind wings are eaten at anyone mating, so that mated males are not precluded from matingagain. As a result, nonvirgin males have fewer material resources tooffer females than do virgin males, such that females shouldbe selected to preferentially mate with high-investment virginmales. We tested the hypothesis that female mating preferencesfavor males capable of supplying females with the highest materialinvestment. Our results indicate that both female diet and opportunitiesfor sexual cannibalism influence female mating behavior. Femalesmaintained on a low-nutrient diet mounted males significantlysooner than females maintained on a high-nutrient diet, indicatingthat a female's overall nutrient intake may determine her propensityto mate. In addition, females were significantly more reluctantto mount and mate with males whose hind wings had been surgicallyremoved and thus were incapable of providing females with awing meal. Finally, females initially mated to dewinged malesremated with winged males significantly sooner than femalesallowed to feed freely during their initial mating, resultingin cryptic female choice of investing males.     

Male but not female pipefish copy mate choice

If mate choice is costly, an individual may reduce the costsof choice by observing and copying the mate choice of others.Although copying has received much attention during the past10 years, evidence of copying is not very strong, partly becauseof problems with distinguishing copying from other mechanismscreating similar mating patterns. I conducted an aquarium experimentusing the deep-snouted pipefish Syngnathus typhle, a specieswith reversed sex roles and mutual mate choice. I tested whethercopying occurred both during male and female mate choice. Theresults showed that males, but not females, displayed more towardan individual, which they perceived as popular among others,and this was interpreted as male mate choice copying. Whilebeing the first evidence of copying in a sex-role–reversedspecies, the sex difference in behavior mirrors the sex-rolepattern and begs the question whether we should predict copyingonly in females in other species with mutual choice but conventionalsex roles.     

MECHANISMS OF FEMALE CHOICE IN RED JUNGLE FOWL

We examined mate preference behavior in red jungle fowl, Gallus gallus, to determine if the mechanism of mate preference used by females was relative or absolute. Under a relative model, females compare males and prefer the one with the most exaggerated form of secondary sex character, regardless of where the proffered males lie along the population distribution of the trait. Under an absolute or threshold model, females have a threshold for the character, above which they will exert a preference and below which they will not. Female red jungle fowl preferred roosters with longer combs and redder irises, but this preference was exerted only when hens mated quickly; females mating slowly mated at random. The threshold model was supported in two ways: i) chosen males from the fast-mating group had larger combs than chosen males in the slow-mating group; ii) when the same female was presented with two pairs of males in two different trials, one large-combed pair and one small-combed pair, hens mated significantly more slowly, and often refused to mate, when only short-combed roosters were available. Hens thus alter their behavior depending on the males they see, and they may not exert a preference at all if both males fall below the threshold. Further corroborating evidence comes from a set of mate choice trials using underdeveloped roosters, in which males had small combs and females mated slowly or did not mate. The method of choice used by females could affect the speed with which correlations develop between the genes for male traits and genes for female preferences. Sexual selection for good genes may be more consistent with an absolute than a relative method of female choice.     

Why is Female Choice not Unanimous? Insights from Costly Mate Sampling in Marine Iguanas

Females do not unanimously choose the single 'best' male, even when female choice is strong, such as in leks, or in polygynous mating situations. A possible explanation is that females base their choices on limited information, perhaps because gathering information is costly. We tested this hypothesis by continuously observing individual female marine iguanas throughout the mating period in order to document the information they gathered about each potential mate. Females actively visited approximately five additional males during the 3 d prior to copulation, compared to the males seen on their normal foraging routes. Females were more likely to visit large-bodied males, but preferentially copulated with the male that had the highest display rate of all males they visited. Females that mated on a dense territory cluster mated with more active males than did those that mated on dispersed territories. However, females on a dense cluster also lost more body mass, potentially as a consequence of high rates of interaction with males. This mass loss may represent an important cost and result from postural changes in response to male attention. Such costs may explain why females only gather a certain amount of information and why females on dispersed territories choose less active mates. Lack of complete information introduces subjectivity into female choice: what is perceived as best by one female may not be perceived as best by another. Thus, lack of complete information may prevent unanimity of female choice.     

Male ornamentation, timing of breeding, and cost of polygyny in the collared flycatcher

Highly ornamented males are often thought to be better ableto provide females with resources, parental assistance, or goodgenes. Individual variation in such male abilities may overridethe costs of polygyny and therefore largely explain within-populationvariation in mating patterns. We investigated the influenceof variation in male ornamentation and the environment on thecosts of polygyny for female collared flycatchers (Ficedulaalbicollis), using data from a long-term study involving 2733breeding attempts over 19 years. We show that females sufferreduced reproductive success when mated polygynously but thatthe costs of polygyny depend on an interaction between maleornamentation and timing of breeding. Among early breeders,polygynously mated females experience higher reproductive successwhen mated to less ornamented males, but among late breeders,females mated polygynously to highly ornamented males were moresuccessful. We suggest that a high effort spent on obtainingextrapair matings early in the season renders highly ornamentedmales less able to assist two females in caring for the young.Thus, a male's ability to simultaneously gain from extrapairmatings and polygyny may be limited through direct effects onfemale reproductive success. Given such limitation, extrapairmatings may be expected to be less frequent in species withbiparental care and a high level of social polygyny.     

Male mate choice in the chameleon grasshopper (Kosciuscola tristis)

In many species, males can increase their fitness by mating with the highest quality females. Female quality can be indicated by cues, such as body size, age and mating status. In the alpine grasshopper Kosciuscola tristis, males can be found riding on subadult females early in the season, and as the season progresses, males engage in fights over ovipositing females. These observations suggest that males may be competing for females that are either unmated (early season) or sperm‐depleted (late season). We thus hypothesised that male K. tristis may be choosy in relation to female mating status, and specifically, we predicted that males prefer females that are unmated. We conducted behavioural experiments in which males were given the choice of two females, one mated and one unmated. Contrary to our prediction, males did not mate preferentially with unmated females. However, copulation duration with unmated females was, on average, 24 times the length of copulation with mated females. While female K. tristis can reject mates, we did not observe any evidence of overt female choice during our trials. Females may gain additional benefits from mating multiply and may therefore not readily reject males. While our experiment cannot definitively disentangle female from male control over copulation duration, we suggest that males choose to invest more time in copula with unmated females, perhaps for paternity assurance, and that male mate assessment occurs during copulation rather than beforehand.     

THE EFFECTS OF BODY SIZE ON MATING FEATURES IN A FIELD POPULATION OF THE HERMAPHRODITIC SEA HARE APLYSIA KURODAI BABA, 1937 (GASTROPODA: OPISTHOBRANCHIA)

Mating behaviour of the hermaphroditic sea hare Aplysia kurodaiBaba was observed in the field to investigate the effects ofbody size on various mating features. Compared with small individuals,large gastropods mated with more partners both as males andas females, and also with larger partners (size-assor-tativemating). Large gastropods also mated more frequently as femalesbut not as males, and tended to be selected as female matingpartners more often than small ones by neighbouring individualsbut not as male partners. All these results suggest some matingadvantage of large individuals over small ones as females, probablybecause of the preference by male partners for large femalepartners. At the same time, the results suggest that the matingadvantage of large size as males may be limited, if any. Thepreference for large female partners is also consistent withthe fact that their mating was longer than that of small ones.The greater advantage of large size in mating as females, thanas males, means that sexual selection at mate determinationacts more strongly on female size than on male size and thatthe direction of total sexual selection at mating is probablyreversed in this hermaphrodite (Received 27 November 1995; accepted 8 February 1996)     

Effects of multiple mating and male eye span on female reproductive output in the stalk-eyed fly, Cyrtodiopsis dalmanni

Females of the stalk-eyed fly, Cyrtodiopsis dalmanni, mate repeatedly during their lifetime and exhibit mating preferencefor males with large eye span. How these mating decisions affectfemale fitness is not fully understood. In this study, we examinedthe effects of multiple mating and male eye span on short-termreproductive output in this species. Experiments that manipulatedthe number of copulations and partners a female received suggested that obtaining a sufficient sperm supply is an important benefitassociated with multiple mating. The average percentage offertile eggs laid by females increased as a function of matingfrequency and ranged from 40% for females mated once, to 80%for females mated continuously. In addition, a high proportionof copulations in this species appeared to be unsuccessful. One-third of all females mated once laid less than 10% fertileeggs. There was no significant difference in reproductive performancebetween females mated to multiple partners and females matedto a single partner. There was also no indication that femalesreceived any short-term reproductive benefits from mating withmales with large eye span. In fact, females mated to males with short eye span laid a higher percentage of fertile eggs thanfemales mated to large eye span males.     

Strong material benefits and no longevity costs of multiple mating in an extremely polyandrous leaf beetle, Chrysochus cobaltinus (Coleoptera: Chrysomelidae)

It is well established that females of many species exhibitpolyandry. Although such behavior often increases female fitnessby augmenting fecundity or enhancing the genetic diversity andvigor of their offspring, it often reduces female longevity.It has been argued that trade-offs between these costs and benefitsshould limit the degree to which females remate. However, theexistence of highly polyandrous species suggests substantialpolyandry benefits and/or minimal costs in some systems. Femalesof the leaf beetle, Chrysochus cobaltinus, are extremely polyandrous,providing an opportunity to examine the factors influencingthe evolution of such behaviors. We compared the fecundity andlongevity of singly mated females, females that mated multipletimes with the same male, and females that mated multiple timeswith different males. Compared with females in the single matingtreatment, females in both multiple mating treatments exhibiteda significant reduction in latency to oviposition and, due toan increase in daily egg production, significant increases inlifetime fecundity. This difference diminished as the time sincelast mating increased. There were no differences in fecunditybetween the 2 multiple mating treatments, indicating that mateidentity does not influence the material benefits of multiplemating. Surprisingly, female longevity did not differ amongtreatments. The pronounced fecundity benefits that females gainfrom multiple mating, coupled with a lack of longevity costs,apparently explains the extreme polyandry in this species. Inaddition, the existence of material fitness benefits via conspecificmatings raises the intriguing possibility that in a C. cobaltinus–Chrysochusauratus hybrid zone, heterospecific matings may confer similarbenefits to Chrysochus females.     

Male insemination decisions and sperm quality influence paternity in the golden orb-weaving spider

In polyandrous species, paternity may be influenced by the timingand frequency of mating. Female spiders possess 2 genital openingsthat lead to separate sperm-storage structures. Thus, even whenmating with a previously mated female, a male may reduce directsperm competition by inseminating the opposite opening to herfirst mate. Such morphology may provide females with greatercontrol over paternity. We examined simultaneously whether malesavoided already inseminated female genital openings and whetherthis behavior varied with the time between successive matings.To explore these questions, we mated female golden orb weaverspiders, Nephila edulis, each to 2 males and manipulated thetiming of their second mating. We documented male inseminationpatterns and explored the influence of male mating decisionson paternity success using the irradiated male technique. Wefound that 60% of males avoided sperm competition by discriminatingagainst inseminated genital openings. Moreover, male matingbehavior had a dramatic impact on the paternity success of irradiatedmales. When males inseminated the same genital opening, thecompetitive ability of the irradiated male's sperm was dramaticallyreduced resulting in lower paternity success. In contrast, whenthe 2 males inseminated opposite genital openings both malessired equal proportions of offspring regardless of their radiationstatus. There was no evidence that the timing of the secondmating affected patterns of paternity. Our data suggest thatdifferences in sperm quality may influence paternity successof N. edulis males under a sperm-competitive scenario. In contrast,females appear to have limited postmating control over paternity.     

Paternity costs from polyandry compensated by increased fecundity in the hide beetle

Polyandry-induced sperm competition is assumed to impose costson males through reduced per capita paternity success. In contrast,studies focusing on the consequences of polyandry for femalesreport increased oviposition rates and fertility. For thesespecies, there is potential for the increased female fecundityassociated with polyandry to offset the costs to males of sharedpaternity. We tested this hypothesis by comparing the proportionand number of offspring sired by males mated with monandrousand polyandrous females in the hide beetle, Dermestes maculates,both for males mating with different females and for males rematingwith the same female. In 4 mating treatments, monandrous femalesmated either once or twice with the same male and polyandrousfemales mated either twice with 2 different males or thricewith 2 males (where 1 male mated twice). Polyandrous and twice-matingmonandrous females displayed greater fecundity and fertilitythan singly mating monandrous females. Moreover, males rematedto the same female had greater paternity regardless of whetherthat female mated with another male. In both polyandrous treatments,male mating order did not affect paternity success. Finally,although the proportion of eggs sired decreased if a male matedwith a polyandrous female, multiply mating females or femalesthat remated with a previous mate laid significantly more eggsand thus the actual number of eggs sired was comparable. Thus,males do not necessarily accrue a net fitness loss when matingwith polyandrous females. This may explain the absence of anyobvious defensive paternity-protection traits in hide beetlesand other species.     

Female preferences for large, heavy mates inSchistocerca americana (Orthoptera: Acrididae)

The significance of female choice in shaping mating systems remains problematic. The following study clearly documents female preferences in a species of grasshopper,Schistocerca americana, over the course of 3 years. Three sets of animals were observed in an outdoor seminatural cage. Females were found to mate more often with large, heavy males. Furthermore, remating by a female within a week was less likely if she mated with a large or heavy male. Because females were found to oviposit 2 days after a mating on average, these large heavy males may also be chosen cryptically (as defined in the literature) and father more offspring.     

Sexual cannibalism and sperm competition in the golden orb-web spider Nephila plumipes (Araneoidea): female and male perspectives

Mating systems are frequently shaped by conflicts over reproductive interests between males and females. Sexual cannibalism canbe an especially dramatic manifestation of such conflicts.However, the resolutions of this conflict differ among sexuallycannibalistic spider species. Cannibalism may be in the interestof both sexes when females consume males as a foraging decisionto improve fecundity and/or males sacrifice their bodies toincrease fertilization success. In other species, females exertsequential choice of partner by selectively terminating copulationthrough cannibalism while males fail to obtain a paternityadvantage. Here, we investigate the adaptive value of cannibalismin the orb-web spider Nephila plumipes where 60% of males donot survive copulation. Virgin females in poor condition aremore frequently cannibalistic and more likely to kill largemales, but the frequency of cannibalism among mated femalesis not influenced by these factors. Instead, males that matewith mated females increase their fertilization success bybeing cannibalized. Cannibalized males generally mate for longer,but longer copulations correspond with increased paternity onlyin mated females. The amount of sperm from particular malesthat a female stored was not influenced by any of the measuredvariables. The number of sperm stored was not related to paternity,nor was there any detectable reduction in sperm number afterfemales had reproduced. Our data suggest that the conflict between the sexes differs between virgin and mated females.Females should always cannibalize a male, but males only gainfrom cannibalism when mating with mated females, not when matingwith virgin females. Interestingly, the frequencies of cannibalismare not different in matings with virgin or mated females.     

Female Age Determines Remating Behavior in Wild Mexican Fruit Flies

Male and female age are important factors that can influence mating and remating behavior. Females can discriminate against or prefer older males, but there have been relatively fewer studies on how female and male age influence female remating. Here we showed in wild flies of the Mexican fruit fly Anastrepha ludens (Loew), that when females were given a choice between males of different ages, younger females preferred to mate with younger males over older males, while older females were less selective. Also, when given a choice between males of different ages, older females had longer copulation durations than younger females. On the other hand, older males and females had lower mating success, compared with young and middle-aged flies under no choice conditions. However, middle-aged females mated faster compared to young females and young males mated faster compared to middle-aged males. Male age did not influence female remating, while female age strongly determined female remating, with no females remating when they were old. It is unclear if female receptivity mechanisms are switched off at older ages, or if females are reluctant to remate due to possible costs of mating. We discuss our results in terms of how male and female age can influence mating decisions.     

Experimental tests of copying and mate choice in fallow deer (Dama dama)

In fallow deer (Dama dama), as well as in other lek-breedingungulates, receptive females arriving at leks commonly joinmales that are defending large harems. This tendency enhancesdifferences in harem size and mating success between males.It could occur because females independendy move to the samemales, because females are attracted to males with females,or because females are attracted to each other. Using controlledexperiments with estrous female fallow deer, we show that, althoughfemales are more attracted to males with harems than to thosewithout, they are as frequently attracted to groups of femaleswithout a male as to female groups with males. We conclude thatfemale fallow deer joining leks are attracted to each otherand copy each other's movements. As yet, there is no firm evidencein fallow deer or in other lek-breeding ungulates that femalescopy each other's choice of mating partners. Key words: Damadama, fallow deer, lek breeding, mate choice, copying behavior.[Behav Ecol 4: 191–193 (1993)]     

Polyandry in grain beetles, Tenebrio molitor, leads to greater reproductive success: material or genetic benefits?

Females that mate with more than one male may derive both materialand genetic benefits, and differentiating between the two benefitsis often difficult. We tested for both material and geneticeffects associated with multiple mating in the highly promiscuousyellow mealworm beetle, Tenebrio molitor. Females that matedfour times to the same male laid more eggs and produced morelarvae than females that mated only once. Whether copulationsoccurred on the same day or over several days, the result wasan immediate increase in the production of eggs by females.Some females were kept on a restricted diet to test whethernutrients in the spermatophore disproportionately benefittedfood-deprived females. Although females on poor diets producedfewer and smaller offspring, diet did not significantly affect the proportional benefit of mating treatment on female fecundity.By controlling for male mating history, we were able to separatethe effects of mating with different males from the effectsof receiving multiple spermatophores from the same male. Femalesthat mated with four different males achieved substantial gainsin numbers of eggs produced (32% increase) beyond those offemales that mated an identical number of times with the same male. We found no evidence that males allocate fewer sperm toprevious mates. Egg hatchability was unaffected by mating behavior,suggesting that genetic incompatibility at that stage is notresponsible for the low reproductive success of females matedwith a single male. These results suggest that females maydelay or reduce oviposition or may be incapable of achieving maximal fecundity until they have gained the material and/orgenetic benefits of mating with multiple males.     

Sexually transmitted parasites and host mating behavior in the decorated cricket

Sexually transmitted diseases play a potentially important rolein the ecology and evolution of host mating behavior. Here,we use a sexually transmitted nematode-cricket (Mehdinema alii–Gryllodessigillatus) system to examine the effects of parasitism on hostmating activity and female choice. Previous work has shown thatinfected male crickets produce a significantly smaller nuptialgift (spermatophylax) than uninfected males. This is expectedto result in reduced spermatophylax feeding duration and earlyampulla removal. Here, we hypothesize that the parasite-mediatedreduction in spermatophylax size will consequently shorten femaleintercopulatory interval. We predict that females mated to infectedmales will exhibit a shorter intercopulatory interval than femalesmated to uninfected males. To test this hypothesis, we experimentallymeasured the behavioral responses of females mated to uninfectedand infected males. We found no significant difference betweenfemale handling of the spermatophylax and ampulla from infectedversus uninfected males. Although the duration of spermatophylaxconsumption is positively correlated with the duration of ampullaattachment, neither of these variables is correlated with femaleintercopulatory interval. Intercopulatory intervals for femalespreviously mated with uninfected versus infected males are notstatistically different. We conclude that parasitism in maleG. sigillatus does not influence female intercopulatory intervalor male mating success. We found no evidence for female matechoice based on male infection status. The lack of female choiceis consistent with theoretical predictions involving parasitesthat are sexually transmitted.     

Vibratory courtship in a web-building spider: signalling quality or stimulating the female?

Courtship behaviour in spiders in the form of premating vibrations by males may function (1) as a male identity signal used for species recognition, (2) in suppression of female aggressiveness, (3) to stimulate female mating behaviour, or (4) as a quality signal used in female choice. We investigated the function of web vibration by male Stegodyphus lineatus in a series of experiments. Regardless of vibratory performance, all males mated successfully with virgin females but only 56.4% of males mated with nonvirgin females. Vibratory performance did not influence male mating success, but heavier males had a higher probability of mating with mated females. Males vibrated less often and produced fewer vibrations when introduced on the web of a mated female. Males that vibrated webs of virgin females mated faster than nonvibrating males, but there was no effect of vibration rate or body mass. There was no effect of male vibratory effort or vibration rate on female reproductive success measured as time to egg laying, clutch size, number of hatched young, number of dispersed young and offspring body mass after a single mating. Males vibrated on abandoned virgin female webs but the response decreased with increasing duration of female absence, suggesting that females produce a web-borne pheromone, which elicits male vibrating behaviour. Mated females were less receptive and not stimulated by male vibrating behaviour. We conclude that male premating vibrations in S. lineatus do not function as a male quality signal selected via female choice. Rather, the primary function of this behaviour may be to stimulate a receptive female to mate. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

Female choice, male interference, and sperm precedence in the red-spotted newt

Darwin first identified female choice and male—male competitionas forms of sexual selection resulting in the evolution of conspicuoussexual dimorphism, but it has proven challenging to separatetheir effects. Their effects on sexual selection become evenmore complicated when sperm competition occurs because spermprecedence may be either a form of cryptic female choice ora form of male—male competition. We examined the effectsof tail height on male—male competition and female choiceusing the sexually dimorphic red-spotted newt (Notophthalmusviridescens viridescens). Experiment 1 examined whether maletail height influenced male mating success. Males with deeptails were more successful at mating with females than thosewith shallow tails. Successful, deep-tailed males also were bigger(snout-vent length; SVL) than unsuccessful, shallow-tailed males,but they did not vary in tail length or body condition. Of these,only tail height and tail length are sexually dimorphic traits.Experiment 2 tested the hypothesis that the differential successof males with deeper tails was due to female choice by examiningboth simultaneous female preference for association and sequentialfemale choice. We found no evidence of female choice. When maleswere not competing to mate with females, tail height did notinfluence male mating success. Successful males did not havedifferent SVL and tail lengths than unsuccessful males. Thus,tail height in male red-spotted newts appears to be an intrasexuallyselected secondary sexual characteristic. Experiment 3 usedpaternity exclusion analyses based on molecular genetic markersto examine the effect of sperm precedence on sperm competitionin doubly-mated females. Sperm precedence likely does not havea pervasive and consistent effect on fertilization success becausewe found evidence of first, last, and mixed sperm usage.