Effect of clutch size on male egg-fanning behavior and hatching success in the goby, Eviota prasina (Klunzinger)

In fish that exhibit paternal care, the females often choose their mates on the basis of male traits that are indicative of the parental ability of the males. In a marine goby, Eviota prasina, males tend their eggs within their nests until hatching, and females prefer males that have longer dorsal fins and exhibit courtship behavior with a higher frequency as their mates. In order to clarify the relationship between these sexually selected traits and the parental ability of males of E. prasina, the factors affecting the hatching success of eggs within male nests and the male parental care behavior were examined in an aquarium experiment. Females spawned their eggs in male nests and the clutch size of females showed a high individual variation (range = 88-833 eggs). The hatching success of eggs within male nests showed a positive correlation with the time spent by males in fanning eggs and the clutch size. In contrast to the prediction, however, the hatching success did not show a significant correlation with the sexually selected traits, i.e., the male dorsal fin length and the frequency of courtship displays. Moreover, multiple regression analysis indicated that the time spent by the males in fanning was the most important factor affecting the survival rate of the eggs. The time spent by males in fanning behavior was influenced by the clutch size within their nests; the fanning behavior of males occurred with a higher frequency when they tended larger clutches. Males are required to invest a greater effort in egg-tending behavior to achieve a higher hatching success when they receive larger clutches, probably due to the greater reward for their parental behavior. Based on their mate choice, females may obtain other benefits such as high quality offspring.     

Are males with more attractive resources more selective in their mate preferences? A test in a polygynous species

In many polygynous species, males typically direct more intensecourtship toward more fecund females. Here we examined thisbehavior in relation to the attractiveness of a male's resource.We used the territorial polygynous beaugregory damselfish (Stegastesleucostictus) and manipulated the quality of male breeding territorieswith two types of artificial sites. We also investigated variablenatural breeding territories. Previous studies have shown thatthese different breeding sites were of different qualities,as judged by the number of eggs accrued by the defending male.Males on all three types of breeding sites did court females,and males using the highest quality sites exhibited significantlyhigher courtship intensity. However, only the group of maleson the highest quality site-type modulated their courtship intensityto female quality (i.e., female size). This indicates that males requiredsome minimal level of resource attractiveness (i.e., a threshold) beforethey exhibited mate preferences based on female quality. Further differencesin the resource attractiveness for males defending the high-qualityartificial sites were not related to differences in courtship behavior.     

Male fruit flies learn to avoid interspecific courtship

Experimental data suggest, and theoretical models typicallyassume, that males of many fruit flies (Drosophila spp) areat least partially indiscriminate while searching for mates,and that it is mostly the females who exert selective mate choice,which can lead to incipient speciation. Evidence on learningby male D. melanogaster in the context of courtship, however,raises the possibility that the initially indiscriminate malesbecome more selective with experience. I tested this possibilityby comparing the courtship behavior of male D. melanogasterexperienced at courting females of the closely related species,D. simulans, and inexperienced males. I found that comparedwith the inexperienced males, the males experienced with courtingD. simulans females showed significantly lower courtship towardfemale D. simulans. Both male treatments, however, showed virtuallyidentical courtship durations with female D. melanogaster. Theseresults indicate that male fruit flies adaptively refine theircourtship behavior with experience and suggest that the malescontribute more to assortative mating and incipient speciationthan is commonly assumed.     

Mate Choice and Spawning Success in the Fighting Fish Betta splendens: the Importance of Body Size, Display Behavior and Nest Size

Courtship displays should be exaggerated enough to attract mates and yet tempered so as not to deter them. We tested this hypothesis in the fighting fish Betta splendens by studying courtship displays and body size and their relationships with male parental quality and female fecundity, as well as the effects of display behavior and body size on mate choice decisions and spawning success. Because of their high degree of parental investment, males are expected to be discriminating in their choice of mates. Males who displayed more frequently built larger nests, a measure of parental quality, but larger males did not. When females were paired with males with high display rates, however, the pair had fewer eggs in their nest, even when accounting for female body mass. In a mate choice test using computer‐generated male stimuli that differed only in display behavior, females showed no preferences for displaying males vs. non‐displaying males, or for males with higher display rates vs. lower display rates. In similar tests in which the computer‐generated males differed only in size, females preferred larger males, but also preferred males that differed with respect to body size (negative assortative mating). Males preferred computer‐generated females that performed courtship displays over non‐displaying females, but showed no preferences for female body size. Neither a female's body size nor her display behavior was a significant predictor of her fecundity as estimated by the number of eggs released during spawning. Thus, our results suggest that female B. splendens must balance male parental quality (nest size) with the risk of potentially disruptive or dangerous behavior during spawning, and that females may minimize these risks through negative size‐assortative mating. Female display behavior, while unrelated to fecundity in our study, may attract males because it indicates reproductive readiness or serves a species‐recognition function.     

Female egg dumping and the effect of sex ratio on male egg carrying in a coreid bug

Phyllomorpha laciniata Vill (Heteroptera, Coreidae) is uniqueamong terrestrial insects in that females glue eggs on the backsof other conspecifics. Egg carrying byP. laciniatamales haspreviously been considered as paternal care. We explored femaleoviposition with respect to previous mating experience of femalesand tested whether sex ratio affects male egg-carrying. Thehypothesis that male egg-carrying is a form of paternal carepredicts that a male should always accept eggs after matingwith a female. However, if male egg-carrying is a form of postcopulatorymate guarding rather than paternal care, egg carrying shouldincrease in the presence of other males. When two couples wereplaced together, females laid eggs on the backs of all individualsenclosed, including the backs of other females. However, whena female was accompanied by 2 males, 22 out of 26 females ovipositedon their mating partner. Thus, sexual competition rather thanpaternity alone, affects a male's eagerness to carry eggs. However,even if males sometimes carry their own eggs, females lay eggson the backs of all conspecifics they can easily acquire. Thus,egg carrying in P. laciniata is partially voluntary and partiallythe result of female egg dumping     

Female preference for preferred males is reversed under low oxygen conditions in the common goby (Pomatoschistus microps)

Female preference for males that already have eggs in theirnest has been reported in many fish species. The presence ofeggs may provide a cue for copying the choice of previous femalesand may indicate that high-quality care will be available. Consistentwith a review of 13 studies, we found that female common gobies(Pomatoschistus microps) preferred to spawn with males thathad already been chosen by females and whose nests therefore alreadycontained eggs. However, this preference was reversed underconditions of low dissolved oxygen. We would not expect thisreversal if the second female were using eggs as a signal ofmale genetic attractiveness to other females unless the benefitswere outweighed by direct selection. The reversal also couldnot be explained by differences in active courtship by males,as courtship rates did not differ under low oxygen between maleswith or without eggs. Low oxygen conditions corresponded witha nearly threefold increase in male ventilation of eggs anda reduction in time spent near a selecting female. The reversalis therefore most likely due to females avoiding males thatwould be unable to meet the demands of care of a second clutchunder low oxygen conditions. Thus, an abiotic feature of theenvironment reveals plasticity of female choice, consistentwith hypothesized changes in benefits of mating with preferredmales.     

Preexisting behavior facilitated the loss of a sexual signal in the field cricket Teleogryllus oceanicus

Behavioral preadaptations can provide an accommodating environmentin which novel morphological characters may be selected. A veryrecent morphological mutation, flatwing, has caused the lossof male song in field crickets (Teleogryllus oceanicus) fromthe Hawaiian island of Kauai. Previous studies in this and relatedspecies have shown that females require male courtship songto mount males, but flatwing T. oceanicus males still achievematings. Females from Kauai may have a relaxed requirement formale courtship song, or flatwing males may compensate for theirinability to sing by altering other courtship behaviors. Wetested whether male courtship and female responses to male courtshipwere preadapted in a way that facilitated the spread of themale wing mutation or if parallel changes in male courtshipand female responses accompanied the mutation. We performedmating trials in 2 captive-bred populations to assess how matingbehavior varied depending on the presence or absence of courtshipsong playback. The first was an ancestral population from Kauaiestablished prior to the emergence of the flatwing mutation,and the second was derived from Kauai after the mutation becameprevalent. Mating behaviors did not differ qualitatively orquantitatively between the ancestral and current populations,and females from both accepted males for mating in the absenceof courtship song. Our results provide direct evidence thata mechanism allowing flatwing males to mate with females wasin place before the mutation actually arose on Kauai and demonstratehow preexisting behavior facilitated the rapid spread of a novelmorphological mutation.     

Female preference for fast-rate, high-pitched calls in Hermann's tortoises Testudo hermanni

The courtship and mounting behavior of promiscuous tortoisesis based on a multiple signaling system that includes visual,olfactory, tactile, and acoustic signals. Vocalizations relatedto mounting seem to be particularly intriguing because tortoisesvocalize mainly at this time. Vocalizations and courtship behaviormight be costly for males, and if these costs increase differentiallyfor different males, then the potential exists for vocalizationsand displays to reveal male individual quality on which femalescould base their mate choice. In the present study, by usingindividuals breeding in seminatural enclosures, we experimentallyinvestigated whether the mounting call of male Hermann's tortoises(Testudo hermanni) represents a relevant stimulus to both malesand females. We also looked for potential preference towarddifferent acoustic stimuli in order to determine which callfeatures, if any, played a role in attracting potential partnersor deterring rivals. Females were sensitive to call playback,whereas males apparently paid little attention to playback.In addition, females showed a significant preference towardhigh-pitched calls emitted at high rate. Also, females exhibiteda strong tendency toward short-duration calls. Because callrate is related to hematocrit in Hermann's tortoise males, byresponding to fast-rate calls females are also choosing high-qualitypartners as sires of their offspring. This is the first studyin which an attractive function of tortoise vocalizations hasbeen documented.     

Male displays and female preferences in the courtship of a gregarious cricket

The courtship of males of the gregarious cricket Amphiacusta maya involves a variety of signals. The quantitative aspects of both successful and unsuccessful courtship sequences were examined to determine whether certain aspects of male displays were correlated with female mating preferences regardless of which male performed them. Although variability among males was high for most courtship components measured, I found no evidence of female choice with respect to the courtship variables studied. About 35% of the duration of each male courtship sequence is devoted to chirping, but there were no differences in either the likelihood of copulation or the latency to copulation between normal males and experimentally silenced males. The possibility that intrinsic differences in male quality explained the variability in courtship duration was examined with a two-way analysis of variance. The variance in courtship duration was attributable to variance among females, not to variance among males. Thus the courtship behaviour of male A. maya is variable enough to allow females to exert stabilizing or disruptive selection on displays, but there is no evidence that females use the available information.     

A female's past experience with predators affects male courtship and the care her offspring will receive from their father

Differential allocation occurs when individuals adjust their reproductive investment based on their partner''s traits. However, it remains unknown whether animals differentially allocate based on their partner''s past experiences with predation risk. If animals can detect a potential mate''s experience with predators, this might inform them about the stress level of their potential mate, the likelihood of parental effects in offspring and/or the dangers present in the environment. Using threespined stickleback (Gasterosteus aculeatus), we examined whether a female''s previous experience with being chased by a model predator while yolking eggs affects male mating effort and offspring care. Males displayed fewer conspicuous courtship behaviours towards females that had experienced predation risk in the past compared with unexposed females. This differential allocation extended to how males cared for the resulting offspring of these matings: fathers provided less parental care to offspring of females that had experienced predation risk in the past. Our results show for the first time, to our knowledge, that variation among females in their predator encounters can contribute to behavioural variation among males in courtship and parental care, even when males themselves do not encounter a predator. These results, together with previous findings, suggest that maternal predator exposure can influence offspring development both directly and indirectly, through how it affects father care.     

Female mate preference in goby Eviota prasina: do secondary sexual traits influence female choice?

Males of the small gobiid fish Eviota prasina have longer dorsal fins than females and use their dorsal fins for courtship displays and male-male competition. We examined the influence of male dorsal fin length as well as the frequency of courtship displays on female mate preference using sequential choice experiments. Females responded more frequently to courting males with longer dorsal fins than males with shorter dorsal fins. This indicates female mate preference on the basis of male dorsal fin length in this goby. In addition, the logistic regression analysis showed that male courtship frequency positively influenced female mate preference. Since males incur costs to produce and maintain longer dorsal fins and to perform frequent courtship displays, these secondary sexual traits may indicate the quality of physical characteristics. In E. prasina, only males conducted parental care for eggs in their nests. Therefore, females may be able to ensure greater survival rates as well as higher genetic quality of their offspring by choosing males with better qualities based on these male traits.     

Sexual selection for structure building by courting male fiddler crabs: an experimental study of behavioral mechanisms

Males of the fiddler crab Uca musica sometimes build sand hoodsat the entrances of their burrows, to which they attract femalesfor mating with claw waving and other displays. Females significantlymore often approached males with hoods than males without hoods,but once at a burrow, they were just as likely to stay andmate whether the male had a hood or not. To determine how hoodsaffect male attractiveness, we conducted experiments that controlledfor other differences in courtship behavior between buildersand nonbuilders; we removed hood builders' hoods and we addedhood models to nonbuilders' burrows. We then measured the attractivenessof hood builders and nonbuilders with and without hoods. Neithermanipulation measurably affected male courtship behavior. Thepresence of a hood did not increase male—female encounterrates, suggesting that hoods do not attract distant femalesinto a male's courtship range. However, once a male courteda female, she was significantly more likely to approach ifhe had a real or model hood. We obtained direct evidence thatfemales orient to hoods by replacing them with hood modelspositioned about 3 cm away from the openings to males' burrows.Females approached the models, not the courting males, about27% of the time. We conclude that hood building is sexuallyselected because courted females differentially approach hoods,not because hoods attract distant females and not because femalesprefer to mate with hood builders.     

Visual and Acoustical Signalling during Courtship by Fiddler Crabs (Genus Uca)

Male fiddler crabs (Genus Uca) employ both visual and acousticalsignals to attract females for mating. In U. pugilator and severalother American species, the males attract females during theday first by waving, then by producing sounds just within theirburrows. At night, the males produce sounds at low rates, butwhen touched by a female, they increase their rate of soundproduction. In the European species, U. tangeri, many elements of courtshipare similar to those in U. pugilator, but two types of soundsare produced. One of these, the short drumwhirl, appears tosubstitute for waving when the male is temporarily obscuredfrom the female during his diurnal courtship activities. Thelong drumwhirl is used under different circumstances. The acoustical responses of a male to a female influence thecourtship behavior of other males in the area. When sounds fromstimulated males are played back to test males during the day,their lates of waving increase. At night, the playbacks elicitincreases in rates of sound production. The influence of tidal oscillations, temperature, and lightcycles on the behavior of males is discussed. Courtship activities of aquatic crabs are compared to thoseof terrestrial Brachyura. In aquatic forms, courtship may beabsent or, if present, does not involve elaborate signallingby the male. Chemical or visual cues at close range are themost important stimuli. In several genera of terrestrial crabs,visual signalling for prolonged periods is common, and soundsare often emitted by males to "call" females from their burrowsto the surface for mating. Some of the factors that may accountfor differences in courtship activities in aquatic and terrestrialspecies are discussed.     

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。     

Unravelling the evolution of complex reproductive traits with phenotypic engineering

The social dynamics surrounding courtship, mating and parental care are complex enough when just a single male and female are involved, but for species that employ multiple strategies for achieving fertilization success, the network of interactions among rivals, allies and suitors can be utterly complicated. Such is the case in the ocellated wrasse, Symphodus ocellatus, in which males adopt one of three mating strategies. The large, colourful “nesting males” court females, defend territories and care for fertilized eggs until they hatch. The smaller “satellite males” help the nesting males court females and guard against the third morph, the “sneaker males”, which sneak in when a nesting male is spawning with a female and surreptitiously release sperm. Sneaker males perform no courtship displays nor defend territories, so their reproductive investment is devoted entirely to sperm production. And these alternative male strategies work: 100% of nests contain some eggs fertilized by sneaker and satellite males, despite the fact that parental care is solely the responsibility of nesting males In this issue of Molecular Ecology, work to untangle the proximate mechanisms regulating the reproductive physiology of nesting males and their behaviour towards other males, which impacts the entire social network. Moreover, they describe how variation in neuroendocrine regulation can give rise to variation in reproductive traits, upon which sexual selection can act.     

Vigorously courting male sticklebacks are poor fathers

Male threespine sticklebacks (Gasterosteus aculeatus) that are unsuccessful at hatching eggs may provide insufficient parental care or have unhealthy or unfertilized eggs. In this study, most males that were unsuccessful at hatching eggs appeared to be poor fathers because they depleted their energy reserves by vigorously courting females and by maintaining intense nuptial coloration during courtship and parental care, leading to reduced fanning of the eggs. Unsuccessful males differed from successful males by investing more in obtaining a clutch of eggs and less in the eggs once they had them, suggesting a trade-off between investing in courtship and investing in paternal care. Received: 14 August 1998 / Received in revised form: 26 August 1999 / Accepted: 6 September 1999     

Paternity in the Australian brush-turkey, Alectura lathami, a megapode bird with uniparental male care

Male Australian brush-turkeys, Alectura lathami, provide allparental care by building and tending large incubation mounds.Females visit and lay eggs in the mounds of several males sequentially,but they provide no parental care after laying. Because malesand females meet only briefly at mounds to copulate and lay,males have no obvious means of ensuring paternity. I used DNAfingerprinting techniques to determine paternity for 65 brush-turkeychicks. Eighteen chicks (27.7%) did not match the mound-tendingmale. Some of these paternity exclusions were evidently causedby females switching rapidly from one mound to another, butthe majority (23.1% of eggs) appeared to result from femalescopulating with males other than the one in whose mound theywere currently laying. However, the frequency of these copulations(43%) was much lower than the estimated frequency with whichthey fertilized eggs, perhaps because their timing during theovulatory cycle differed relative to most other copulations.The percentage of eggs excluded in paternity analyses rangedfrom 20.0% to 43.8% for individual males but did not appearto affect male parental care. Several factors favor male parentalcare regardless of paternity. Males can accommodate eggs fromseveral females in one mound, which increases the opportunitiesfor additional matings without increasing the cost of parentalcare. In addition, paternity appears to be unpredictable andhard to assess, and a facultative reduction in care would bedifficult without abandoning a mound entirely.     

Male mating strategies under predation risk: do females call the shots?

Many authors have reported that, under elevated risk of predation,male guppies (Poecilia reticulata) alter their behavior fromcourtship to forced copulation (gonopodial thrusts not precededby sigmoid displays). This shift is presumed to benefit thebrightly colored male, whose intense courting activity mightotherwise increase his risk of detection and attack by predators.However, there is some evidence that females engaged in reproductiveactivity with males may be even more vulnerable to predatorsthan the males themselves, which suggests an alternative hypothesis:females in high-risk situations are less receptive to male courtship,and this leads males to change their behavior. We tested thishypothesis by providing either males and females separately,or both sexes concurrently, with information about elevatedpredation risk from a cichlid (Crenicichla sp.). We found thatwhen only females were provided with information about increased risk,males performed fewer courtship displays and fewer thrusts.They did not perform more forced copulations in any treatmentgroup. Nonetheless, our results suggest that the female's perceptionof predation risk can be at least as important as the male'sin changing male mating behavior.     

Females produce larger eggs for large males in a paternal mouthbrooding fish.

When individuals receive different returns from their reproductive investment dependent on mate quality, they are expected to invest more when breeding with higher quality mates. A number of studies over the past decade have shown that females may alter their reproductive effort depending on the quality/attractiveness of their mate. However, to date, despite extensive work on parental investment, such a differential allocation has not been demonstrated in fish. Indeed, so far only two studies from any taxon have suggested that females alter the quality of individual offspring according to the quality/attractiveness of their mate. The banggai cardinal fish is an obligate paternal mouth brooder where females lay few large eggs. It has previously been shown that male size determines clutch weight irrespective of female size in this species. In this study, I investigated whether females perform more courtship displays towards larger males and whether females allocate their reproductive effort depending on the size of their mate by experimentally assigning females to either large or small males. I found that females displayed more towards larger males, thereby suggesting a female preference for larger males. Further, females produced heavier eggs and heavier clutches but not more eggs when paired with large males. My experiments show that females in this species adjust their offspring weight and, thus, presumably offspring quality according to the size of their mate.     

Do Psyttalia concolor (Hymenoptera: Braconidae) males gain in mating competitiveness from being courted by other males while still young?

The role of male–male courtship in parasitic wasps is not well understood and nothing has been reported on the implication of learning in regard to homosexual behavior in hymenopteran parasitoids. In Psyttalia concolor (Hymenoptera: Braconidae), a synovigenic koinobiont larval–pupal endoparasitoid of many Diptera Tephritidae of economic importance, courtship and mating attempts are frequently displayed among males. Here we determine whether P. concolor males that are courted while still young by sexually mature males can compete better with other males when they court females. The results showed that P. concolor immature males do not appear to gain from receiving male courtship, but they develop a higher intensity (more wing fanning and shorter latency time) in the successive courtship of the females. The hypothesis that, under some conditions, such higher courtship intensities may increase the probability of gaining a mating advantage is discussed.