Variation in Male Calling Behaviour and Relation to Male Mating Success in the Strawberry Poison Frog (Dendrobates pumilio)

Calling behaviour and the characteristics of the males’ call are important for mate attraction, female mate choice and male mating success in anurans. In this study I investigated the variation in calling activity and the variation in one spectral (dominant frequency) and four temporal properties (call rate, call duration, duty cycle and pulse rate) of the advertisement call of strawberry poison frogs, Dendrobates pumilio, in two Costa Rican populations during two study periods. Regarding all call properties, no differences were found between populations or years, but between‐male variation was significantly higher than within‐recording and within‐male variation. Dominant frequency was less variable within and among males than temporal call properties and I classified the former as static and the latter as intermediate properties of the call. No call property seemed to be strongly affected by body length or weight. Moreover, I used behavioural observations to relate male calling behaviour to mating success. Calling activity was more variable between males and accounted for more variability in mating success in multiple regression models than any call property. Some call properties (call rate, dominant frequency and pulse rate) were also related to male mating success in one or two study periods. These call properties are probably important for females during courtship to assess their prospective mate and/or for competitive male–male interactions. Furthermore, I compared call properties and mating success of some males for which data were available for both study periods. Pulse rate was lower in the second than in the first year, suggesting age‐related changes in this call property. Moreover, male D. pumilio increased their relative mating success from the first to the second study year. Together with other studies, the data of this study suggest that, in anurans, endurance rivalry contributes more to variation in male mating success than does female choice based on male characteristics.     

Male Mating Success and the Effect of Mating History on Ejaculate Traits in a Facultatively Parthenogenic Insect (Extatosoma tiaratum)

Males can typically increase their lifetime reproductive success by mating with multiple females. However, recent studies across a broad range of species have demonstrated physiological constraints on male multiple mating. In this study, we investigate male mating capacity in Extatosoma tiaratum, a facultative parthenogenetic phasmatid. Sperm limitation is thought to be one factor favouring the evolution and maintenance of parthenogenetic reproduction, but studies on male mating ability in facultative parthenogenetic species are extremely rare. To explore whether male mating success varies with mating history, we provided males with weekly mating opportunities with different females throughout their lives. We then observed mating success, and the variation in ejaculate size and quality within each mating. We showed that most, but not all, males can mate multiply, however the amount of ejaculate produced is variable and depends upon male body mass and mating history.     

The role of mating history and male size in determining mating behaviours and sexual conflict in a water strider

We conducted three experiments to test the effects of mating history of both sexes and of male body size on mating behaviours in the water strider, Gerris buenoi. Our manipulations influenced the interests of both sexes and, thus, the degree of conflict over mating behaviours. Mating history was a dichotomous variable (deprived/mated), depending on holding conditions in the laboratory. Experiment 1 considered and found independent effects of male and female mating history on latency to copulation and copulation duration. In experiment 2, we manipulated only female mating history, using unsuccessful struggle rates as evidence for female reluctance and conflict over mating. Finally, we investigated the relation between male body size and mating history on copulation duration. We predicted that intersexual conflict over mating would be lowest when females were deprived, because female interests under these conditions should more closely match those of males. Deprived females began mating in half the time of mated females and were twice as likely to mate because of reduced reluctance. Furthermore, copulation duration for deprived males was about one and a half times longer than that for mated males. Although previous studies examining nonrandom mating patterns by size predicted longer copulations for small males, we found that small males prolonged copulation when deprived more than large males. We conclude that females primarily influence copulation frequency, but males primarily influence copulation duration. Our results favour the hypothesis that reduced mating opportunity for small males accounts for their extended copulation duration. Finally, our findings provide evidence for strong effects of male body size on selection mechanisms in water striders, and support the hypothesis of conflicting pre- and postcopulatory selection mechanisms in this group. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.     

Male courtship success and female discrimination in the mediterranean fruit fly (Diptera: Tephritidae)

The mating success of individually marked male Mediterranean fruit flies was monitored over 6 consecutive days in the laboratory. Mating frequency was nonrandom, as the numbers of both males that failed to mate and males that mated many (more than four) times were much higher than expected by chance alone. Differential mating success resulted in part from intermale variation in activity level. Male copulatory success was positively correlated with the numbers of courtships performed, attempted copulations (mountings), and females courted. Male-male aggression, on the other hand, and a negligible effect on male mating success. Female choice also appeared to influence male mating frequency. Fewer than 10% of courtships resulted in mating, and in most cases females terminated courtship by simply moving away from the male. Females that did mate generally selected males having higher copulatory scores than previously rejected males.     

MALE DOMINANCE, FEMALE MATE CHOICE, AND INTERSEXUAL CONFLICT IN THE ROSE BITTERLING (RHODEUS OCELLATUS)

An intersexual conflict arises when males and females differ in their reproductive interests. Although experimental studies have shown that females often mate with dominant males, it may not always be in the interest of a female to do so. Here we investigated the impact of male dominance on female mate choice and offspring growth and survival in the rose bitterling ( Rhodeus ocellatus ), a freshwater fish with a resource-based mating system. Three experimental mating trials were conducted using males of known dominance rank, but with different levels of constraint on male behavior. Thus, females were able to choose among; (1) males that were isolated from each other; (2) males that could see and smell each other, but could not directly interact; (3) males that could interact fully. Using a combination of behavioral observation and parentage analyses it was shown that female preferences did not correspond with male dominance and that male aggression and dominance constrained female mate choice, resulting in a potential intersexual conflict. The survival of offspring to independence was significantly correlated with female mate preferences, but not with male dominance. A lack of strong congruence in female preference for males suggested a role for parental haplotype compatibility in mate choice.     

Cost of reproduction in male medflies: The primacy of sexual courting in extreme longevity reduction

In polygynous insect species, male reproductive success is directly related to lifetime mating success. However, the costs for males of sexual activities such as courting, signaling, and mating are largely unknown. We studied the cost of sexual activities in male Mediterranean fruit flies, Ceratitis capitata (Tephritidae), a polygynous lekking species, by keeping cohorts of individual male flies under relaxed crowding conditions in the laboratory. We used 5 cohorts among which individuals differed in their opportunities to interact with con-specifics and recorded life span, and in one treatment, mating rate. We found that males kept singly lived more than twice as long as males that interacted intensively with mature virgin females, while male-male interactions caused a smaller reduction in longevity. Because longevity of males that could court but not mate was not significantly different from those that could court and mate, we conclude that courting (not mating) was responsible for the observed longevity reduction. Moreover, we detected high variability in male mating success, when 5 virgin females were offered daily. In contrast to the cohort level, individual males that mated at a high rate lived relatively long, thus indicating heterogeneity in quality or sexual strategy among males.     

The Starling Mating System as an Outcome of the Sexual Conflict

Many bird species demonstrate a variable mating system, with some males being monogamously mated and other males able to attract more than one mate. This variation in avian mating systems is often explained in terms of potential costs of sharing breeding partners and compensation for such costs. However, whenever there is a difference in the optimal mating system for males and females, a sexual conflict over the number of partners is expected. This paper contains a verbal model of how a conflict between male and female European starlings (Sturnus vulgaris),resulting from the fitness consequences of different mating systems for males and females differing over time, determines the mating system. We demonstrate that males and females have contrasting fitness interests regarding mating system, such that males gain from attracting additional mates whereas already mated females pay a cost in terms of reduced reproductive success if males are successful in attracting more mates. We demonstrate how this can be traced to the rules by which males allocate non-sharable care between different broods. Furthermore, we demonstrate that there exist male and female conflict behaviours with the potential to affect the mating system. For example, aggression from already mated females towards prospecting females can limit male mating success and males can circumvent this by spacing the nest-sites they defend. The realised mating system will emerge as a consequence of both the fitness value of the different mating systems for males and females, and the costs for males and females of intersexual competition. We discuss how this model can be developed and critically evaluated in the future.     

Lifetime mating success of males in a natural population of the papilionid butterfly,Atrophaneura alcinous (Lepidoptera: Papilionidae)

Lifetime mating success of males in a natural population of the papilionid butterfly, Atrophaneura alcinous, was investigated and causes of the variation were examined. The most successful males mated with 5 females, whereas about 73% of the males failed to mate. Body size of males was not correlated with their eclosion date, longevity and lifetime mating success. There was no trade-off between mating success and longevity, and long-lived males had a disproportionately high mating success. Although number of available females per male per day was not variable among males with different longevities, long-lived males had higher mating efficiency. Time interval between matings by non-virgin males was shorter than that from eclosion to the first mating. High lifetime mating success of long-lived males was strongly related to their mating experience, not to their age per se.     

Variation between and within the sexes in body size preferences

Although it is often assumed that males and females have mating preferences for larger individuals of the other sex, potential underlying differences between male and female preferences for body size are not commonly investigated. Here, sexual differences in body size preferences are examined in the poeciliid fish, Brachyrhaphis rhabdophora. Females preferred larger males to smaller males, but preference did not appear to be affected by female size. One population-level analysis for males did not indicate an overall preference for larger females. A closer examination, however, revealed an effect of male size on preference; larger males preferred larger females, while smaller males preferred smaller females. It appears then that females, regardless of size, share a preference for large males, but males differ in their behaviour, depending on their body size. In addition, while the degree of difference in size between paired females did not appear to affect male preference, the degree of difference in size between paired males strongly affected female preference; the greater the difference, the more strongly females preferred the larger male. Thus, intersexual selection is found to operate in both sexes, but how it operates appears to differ. Intrasexual and intersexual differences in mating behaviour may be missed when evaluating population-wide preferences. That is, there can be underlying differences in how the sexes respond and the consequences of such differences should be considered when investigating mate choice. The results are considered in terms of the evolution of mating preferences, alternative mating strategies, assortative mating, the maintenance of trait variation in a population, and current methods to evaluate mating preferences.     

Variation in Male Mate Choice in Drosophila melanogaster

Male mate choice has been reported in the fruit fly, Drosophila melanogaster, even though males of this species were previously thought to maximise their fitness by mating with all available females. To understand the evolution of male mate choice it is important to understand variation in male mating preferences. Two studies, using different stock populations and different methods, have reported contrasting patterns of variation in male mate choice in D. melanogaster. Two possible explanations are that there are evolved differences in each stock population or that the methods used to measure choice could have biased the results. We investigated these hypotheses here by repeating the methods used in one study in which variable male mate choice was found, using the stock population from the other study in which choice was not variable. The results showed a significant resource-independent male preference for less fecund, smaller females, which contrasts with previous observations of male mate choice. This indicates that different selection pressures between populations have resulted in evolved differences in the expression of male mate choice. It also reveals phenotypic plasticity in male mate choice in response to cues encountered in each choice environment. The results highlight the importance of variation in male mate choice, and of identifying mechanisms in order to understand the evolution of mate choice under varying ecological conditions.     

Male-male interactions and their influence on the mating behavior and success in the fountain darter, <Emphasis Type="Italic">Etheostoma fonticola</Emphasis>

Behavioral interactions between individuals of the same sex can affect the outcome of intersexual selection. For this reason, intrasexual selection is oftentimes examined independently from intersexual selection in studies aimed at understanding mating behaviors. However, a more complete understanding of sexual selection effects within a population can only come from exploring both intrasexual and intersexual selection and the potential interactions between the levels of selection. Association preferences in male and female Etheostoma fonticola do not reveal a size preference for same sex or opposite-sex individuals. However, male-male interactions may influence female choice in E. fonticola. We examined whether male E. fonticola that differ in body size exhibit differences in agonistic behaviors and mating success. Larger males do exhibit higher rates of aggressive behaviors and smaller males, in turn, exhibit more defensive behaviors. However, differences between larger and smaller males in male-male interactions did not translate into differences in spawning success. These results suggest that male size influences dominance relationships in E. fonticola but not mating success. There were also no differences between large and small males in mating attempts, which could be an outcome of the year-round breeding season found in this species, females laying eggs singly, or males fertilizing eggs individually.     

Indicators of recent mating success in the pipevine swallowtail butterfly (Battus philenor) and their relationship to male phenotype

A key determinant of the intensity of sexual selection acting on a trait is how variation in that trait is related to variance in reproductive success of individuals. This connection compels efforts to assess lifetime mating number and how it varies among individuals in a population. In the Lepidoptera, female mating success can be assessed relatively easily by counting by the number of spermatophores in the female’s copulatory sac but male mating success in the field can often only be documented by observing copulations. Here we report a method for identifying whether or not males have recently mated that relies on the effect of mating on the appearance of the male’s reproductive tract in the pipevine swallowtail, Battus philenor. In this species laboratory experiments reveal that during mating, components of a male’s reproductive tract become shorter, decrease in mass, and change in appearance, irrespective of male age. These changes persist for at least two days after mating. After documenting these indicators of recent mating, we examined the reproductive tract of 68 field-caught males and found that twelve (17.6%) showed strong evidence of having mated recently. We found that older males were more likely to have recently mated. In addition, the color of the dorsal hindwing, a feature that females use in mate choice, was significantly greener in males, that according to our criteria, had recently-mated than in males that had not.     

Multiple ornamentation, female breeding synchrony, and extra-pair mating success of golden whistlers (Pachycephala pectoralis)

Considerable variation exists in rates of extra-pair paternity between species, and across and within populations of the same species. Explanations for this variation include ecological (e.g. breeding synchrony), morphological (e.g. ornamentation), and genetic (e.g. relatedness) factors, but it is rare for studies to simultaneously explore these factors within a single population. This is especially true for highly ornamented species, where mate choice based on ornamentation may be more complex than in less-adorned species. We conducted such a study in a migratory population of the highly ornamented golden whistler (Pachycephala pectoralis). We quantified male genetic reproductive success and related it to a range of factors putatively involved in determining extra-pair mating success. We found no effects of genetic factors (male heterozygosity and relatedness) on extra-pair success, nor of territory size, male age, or incubation effort. Instead, males possessing yellower breast plumage and large song repertoires enjoyed higher reproductive success. Additionally, we found a negative relationship between local breeding synchrony and male extra-pair mating success. This may be a consequence of mate guarding during the female fertile period and an inability of males to simultaneously mate-guard and pursue extra-pair fertilisations. In this species, the opportunity for extra-pair matings appears to vary temporally with an ecological variable (local breeding synchrony), while fine-scale, inter-male differences in mating success may be influenced by individual attributes (male ornamentation). The migratory nature of the study population and its lack of natal philopatry may mean that relatedness and inbreeding avoidance are less important considerations in mate choice.     

A trade-off generated by sexual conflict: Mediterranean wrasse males refuse present mates to increase future success

A variety of mechanisms, including intrasexual competition,intersexual conflict, and physiological constraints, can explainpatterns of reproduction and the adaptive value of specificbehaviors. In a Mediterranean wrasse, Symphodus ocellatus (Labridae),large, nesting males occasionally refuse to spawn with willingfemales in the presence of small, sneaker males. We exploredthe possible adaptive significance of this behavior. Nestingmales refuse females despite the fact that it reduces theirimmediate mating success. This nesting-male behavior also decreasesfemale and sneaker mating success and occurs when sneaker malessurround the nest. Experiments that decreased the number ofsneakers around nests showed that nesting males respond immediatelyto mating opportunities when fewer sneakers are present, andthus they are not simply constrained by a lack of energy orlack of sperm. Experiments that increased the number of sneakersat the nest caused nesting males initially to refuse spawningopportunities, followed by a subsequent decrease in sneakerpresence and an increase in mating rate. We propose that thisbehavior is the result of a trade-off between immediate matingsuccess and future reproduction created by competition betweenmales and conflict between the sexes. Males reduce their immediatemating success by reducing spawning at the nest; sneaker malessubsequently leave, and this decreases mate competition forthe nesting male. Unresponsiveness of nesting males also causessexual conflict between females and nesting males over mating.We argue that this behavior and the existence of a trade-offcan only be understood by examining intersexual conflict andintrasexual competition simultaneously.     

The sexual arms race and phenotypic correlates of mating success in the waterstrider,Aquarius remigis (Hemiptera: Gerridae)

Intersexual conflicts over mating decisions may have an important impact on the evolution of mating behaviours and strategies and may develop into an arms race between the sexes. In waterstrider species, where intersexual conflict is known to occur, the evolution of male traits that allow them to overcome female reluctance to mate is expected. Reproductively active waterstriders,Aquarius remigis, were videotaped in the laboratory to examine the influence of total body length and front femoral width of males, male: female body size ratio, and female reproductive condition (number of mature eggs) on three variables associated with mating success: duration of the premating struggle, duration of mating, and number of successful matings. None of these behaviors was significantly correlated with the size ratio of the mating pair. However, total body length was negatively correlated with premating struggle duration, male front femoral width was positively correlated with number of successful matings, and number of mature eggs in females was positively correlated with duration of both the premating struggle and the mating itself. The relative influence of male sexual armaments and female choice on the outcome of mating interactions is discussed.     

Female Choice or Male Sex Drive? The Advantages of Male Body Size during Mating in Drosophila Melanogaster

The mating success of larger male Drosophila melanogaster in the laboratory and the wild has been traditionally been explained by female choice, even though the reasons are generally hard to reconcile. Female choice can explain this success by virtue of females taking less time to mate with preferred males, but so can the more aggressive or persistent courtships efforts of large males. Since mating is a negotiation between the two sexes, the behaviors of both are likely to interact and influence mating outcomes. Using a series of assays, we explored these negotiations by testing for the relative influence of male behaviors and its effect on influencing female courtship arousal threshold, which is the time taken for females to accept copulation. Our results show that large males indeed have higher copulation success compared to smaller males. Competition between two males or an increasing number of males had no influence on female sexual arousal threshold;—females therefore may have a relatively fixed ‘arousal threshold’ that must be reached before they are ready to mate, and larger males appear to be able to manipulate this threshold sooner. On the other hand, the females’ physiological and behavioral state drastically influences mating; once females have crossed the courtship arousal threshold they take less time to mate and mate indiscriminately with large and small males. Mating quicker with larger males may be misconstrued to be due to female choice; our results suggest that the mating advantage of larger males may be more a result of heightened male activity and relatively less of female choice. Body size per se may not be a trait under selection by female choice, but size likely amplifies male activity and signal outputs in courtship, allowing them to influence female arousal threshold faster.     

Ecological context and the importance of body and gnathopod size for pairing success in two amphipod ecomorphs

Ecological context generates interspecific variation in mating behavior by imposing differential constraints on the action of sexual selection, but operation of these constraints in nature is not well understood. We used field and laboratory studies to examine the importance of body size and size of sexually dimorphic appendages, the gnathopods, for pairing success in two freshwater amphipod species within the Hyalella azteca species complex. We focused on a large-bodied species found in habitats where ecological factors tend to favor large body size, and a small-bodied species in habitats where small body size is favored by size-selective predation. A field study indicated that although male pairing success was greater for larger males in both species, pairing success increased throughout the range of variation in male size in the large species, whereas, in the small species, pairing success was low for smaller individuals, but roughly constant across intermediate to larger sizes. A laboratory mate choice experiment was consistent with the field study, finding that females of the large species exhibited a preference for larger males that was independent of absolute male size, but females of the small species were indifferent when choosing between males of intermediate to larger size. Species also differed in the direction of sexual size dimorphism in the field, with males being the larger sex in the large species but the smaller sex in the small species, a pattern consistent with the species differences in mate preference. Large gnathopod size relative to body size was associated with enhanced pairing success across all body sizes for the large species, but, in the small species, large gnathopod size enhanced pairing success only in smaller males. Species differences in mating behavior appear consistent with change driven by differing forms of the interaction between sexual and natural selection.     

Male eyespan size is associated with meiotic drive in wild stalk-eyed flies (Teleopsis dalmanni)

This study provides the first direct evidence from wild populations of stalk-eyed flies to support the hypothesis that male eyespan is a signal of meiotic drive. Several stalk-eyed fly species are known to exhibit X-linked meiotic drive. A recent quantitative trait locus analysis in Teleopsis dalmanni found a potential link between variation in male eyespan, a sexually selected ornamental trait, and the presence of meiotic drive. This was based on laboratory populations subject to artificial selection for male eyespan. In this study, we examined the association between microsatellite markers and levels of sex ratio bias (meiotic drive) in 12 wild T. dalmanni populations. We collected two data sets: (a) brood sex ratios of wild-caught males mated to standard laboratory females and (b) variation in a range of phenotypic traits associated with reproductive success of wild-caught males and females. In each case, we typed individuals for eight X-linked microsatellite markers, including several that previously were shown to be associated with male eyespan and meiotic drive. We found that one microsatellite marker was very strongly associated with meiotic drive, whereas a second showed a weaker association. We also found that, using both independent data sets, meiotic drive was strongly associated with male eyespan, with smaller eyespan males being associated with more female-biased broods. These results suggest that mate preference for exaggerated male eyespan allows females to avoid mating with males carrying the meiotic drive gene and is thus a potential mechanism for the maintenance and evolution of female mate preference.     

FEMALES RECEIVE A LIFE-SPAN BENEFIT FROM MALE EJACULATES IN A FIELD CRICKET

Abstract.— Mating has been found to be costly for females of some species because of toxic products that males transfer to females in their seminal fluid. Such mating costs seem paradoxical, particularly for species in which females mate more frequently than is necessary to fertilize their eggs. Indeed, some studies suggest that females may benefit from mating more frequently. The effect of male ejaculates on female life span and lifetime fecundity was experimentally tested in the variable field cricket, Gryllus lineaticeps. In field crickets, females will mate repeatedly with a given male and mate with multiple males. Females that were experimentally mated either repeatedly or multiply lived more than 32% longer than singly mated females. In addition, multiply mated females produced 98% more eggs than singly mated females. Because females received only sperm and seminal fluid from males in the experimental matings, these life‐span and fecundity benefits may result from beneficial seminal fluid products that males transfer to females during mating. Mating benefits rather than mating costs may be common in many animals, particularly in species where female mate choice has a larger effect on male reproductive success than does the outcome of sperm competition.     

Female sand gobies prefer good fathers over dominant males

Female preference for males successful in male-male competition is generally assumed to result in mating with high quality males. Here I report results from an experiment disentangling the effects of intra- and intersexual selection in the sand goby, Pomatoschistus minutus, a marine fish that exhibits paternal care. I show that large males are successful in male–male competition, but contrary to what one would expect, dominants are not preferred by females and are not better at taking care of the eggs. Female preference, however, correlated with the subsequent hatching success of the eggs. Thus, female choice selects for good parenting. Hence, direct benefits in the form of superior paternal care can explain female choice in this species, supporting a good parent process of sexual selection. However, choosing on the outcome of male–male competition does not enable females to mate with the ''best'' males.