Variation In Mating Behaviour Research Articles

SEXUALLY ANTAGONISTIC COEVOLUTION IN A MATING SYSTEM: COMBINING EXPERIMENTAL AND COMPARATIVE APPROACHES TO ADDRESS EVOLUTIONARY PROCESSES

We combined experimental and comparative techniques to study the evolution of mating behaviors within in a clade of 15 water striders (Gerris spp.). Superfluous multiple mating is costly to females in this group, and consequently there is overt conflict between the sexes over mating. Two alternative hypotheses that could generate interspecific variation in mating behaviors are tested: interspecific variation in optimal female mating rate versus sexually antagonistic coevolution of persistence and resistance traits. These potentially coevolving traits include male grasping and female antigrasping structures that further the interests of one sex over the other during premating struggles. Both processes are known to play a role in observed behavioral variation within species. We used two large sets of experiments to quantify behavioral differences among species, as well as their response to an environmentally (sex-ratio) induced change in optimal female mating rate. Our analysis revealed a large degree of continuous interspecific variation in all 20 quantified behavioral variables. Nevertheless, species shared the same set of behaviors, and each responded in a qualitatively similar fashion to sex-ratio alterations. A remarkably large proportion (> 50%) of all interspecific variation in the magnitude of behaviors, including their response to sex ratio, could be captured by a single multivariate axis. These data suggest tight coevolution of behaviors within a shared mating system. The pattern of correlated evolution was best accounted for by antagonistic coevolution in the relative abilities of each sex to control the outcome of premating struggles. In species where males have a relative advantage, mating activity is high, and the opposite is found in species where females have gained a relative advantage. Our analyses also suggested that evolution has been unconstrained by history, with no consistent evolutionary tendency toward or away from male or female relative advantage.Corresponding Editor: P. Dunn

The repeatability of a sexual conflict over mating

Measuring individual variation in mating behaviour is an integral part of studies of sexual selection and of considerable theoretical importance. Few studies, however, have examined individual variation in mating behaviour in a sexual conflict system and considered how individual variation influences the strength and consistency of the resulting sexual selection. We examined variation in mating behaviour of male and female pairs in the seaweed fly, Coelopa frigida. Sexual selection in seaweed flies occurs as a result of a sexual conflict over mating, with larger males generally able to overcome female rejection responses. We explored male and female mating conflicts and examined the variation in conflict outcomes within and between pairs. First, female willingness to mate was unaffected by short-term mating experience, allowing us to examine repeated interactions between a male and a female. Second, the outcomes of the sexual conflict over mating (copulation or rejection), and components of the mating interaction (number of copulations and time the male is mounted), were strongly repeatable. Third, the patterns of sexual selection on male size were consistent across mounts. Individual pairs consistently gave the same outcome to the mating conflict and yielded consistent sexual selection. Sexual conflict systems can thus be studied in the same way as those with more traditional forms of sexual selection and yield important insights into the links between variation in mating behaviour and sexual success.

Habitat structure, female distribution, and fallow deer Dama dama mating stands

Male fallow deer Dama dama exhibit inter and intrapopulation variation in mating behaviour, including both territorial and non‐territorial mating tactics. During 1993 I investigated the relationship between fallow deer mating territory location and female distribution in relation to habitat characteristics at the Ottenby nature reserve in southern Sweden where males defend isolated mating stands during the autumn rut. Mating stands were positively associated with dense canopy cover and the presence of hazel Corylus avellana trees, but negatively associated with the number of alder Alnus glutinosa trees. Preference for such sites may be connected with the types of display males engage in during the rut as both auditory and olfactory means of communication can be affected by habitat structure. In relation to one another, the stands were randomly dispersed throughout the wooded region and along the perimeter of fields, with no indication of clumping or overdispersion. Female distribution was not associated with any of the habitat characteristics, or with stand location. The idea that males might be defending areas of favoured resources was ruled out as a possible explanation for stand location, although the idea that males might be defending game trails frequented by females remains as a potential determinant of stand locations.

Individual variation in male vocal traits and female mating preferences inBufo americanus

We investigated the amount of variation in mating behaviour between and within individual male and female American toads, because both sources of trait variation can influence the course of sexual selection. Males varied in all four call parameters investigated (dominant call frequency, pulse rate, call rate and call duration). Individual males lowered the dominant frequency of their call when they interacted vocally with nearby males. Dominant call frequency was more highly correlated with body size in vocally interacting males than in non-interacting males. Pulse rate of calls primarily varied with water temperature. Call rate and call duration showed the most variation of the four call properties, but this variation was unrelated to male morphology or social interactions. Females varied in three aspects of mating behaviour: two measures of pair formation and their preference for dominant frequency of male calls. The body size of paired males varied between females both in pairings initiated by either sex and in pairings initiated only by females. Males chosen by females were usually larger than average, although age and prior breeding experience of females did not affect mate choice. Playback experiments indicated that female preference for calls of low dominant frequency depended on the temporal patterning of alternative calls presented. Each of the four male vocal properties showed significant repeatability, but only one of the three aspects of female mating behaviour was repeatable. We discuss how different degrees of repeatability in sexual traits of males and females may influence the action and detection of sexual selection in this and other species.

Repeatability of mating behaviour in Montandon’s newt, Triturus montandoni (Caudata Salamandridae)

Models of sexual selection assume that there is genetic control of mating behaviour. A useful tool for studies of consistency in male display and female mate preference is repeatability, a quantitative genetics measure that sets an upper limit on heritability. In this study, repeatability of several parameters of courtship behaviour in Montandon’s newt, Triturus montandoni, were calculated. Only one characteristic of male display had repeatability significantly different from zero. Estimates of repeatability for absolute female preferences with respect to two male characteristics were near-zero. Other parameters of female mating behaviour were also inconsistent. The results may suggest that there is little additive genetic variation in mating behaviour.

Intraspecific Variation in Courtship and Copulation Frequency: an Effect of Mismatch in Partner Attractiveness?

AbstractThe aim of this paper is to present a verbal theoretical model that could account for the among pair variability in courtship and copulation behaviour that occurs both during and after pair formation in socially monogamous species. We assume that copulation acts to prevent mate loss, by reducing the availability of an individual to other potential partners. Variation in copulation and courtship frequency then arises as a result of variation in the risk of mate loss. Because of the constraints on free or ideal choice, pairs will form in which it may be possible for one individual to improve upon the quality of its partner. In a mismatched pair it will pay the poorer quality mate to guard the higher quality individual and prevent it from leaving to pair with a better quality mate. The poor quality individual will therefore solicit copulations at a high frequency while it's partner may not always respond. We predict that high levels of courtship and solicitation will relate to a high risk of mate loss and that a lack of response by a partner will relate to the potential opportunities it has to improve on partner quality. Our thesis is that variation in mating behaviour arises as a result of any deviations from assortative mating that may exist in a population.

Alternative mating strategies in a desert grasshopper: evidence of density-dependence

Field observations revealed that, on a given day, male mating behaviour in a population of the grasshopper Ligurotettix coquilletti ranged from little or no stridulation (inactive) to relatively persistent singing (active signalling). Inactive males were usually located in the territories of active signallers. Actively signalling male achieved more matings, and also more frequently approached and mounted females in incidents terminating in the male departing the female without copulating. Individuals switched between inactive and actively-signalling behaviour during their adult lives, and males that were usually active signallers achieved greater lifetime mating success. Thus, we obtained no evidence to support the hypothesis that variation in mating behaviour was maintained by negative frequency-dependent selection. By comparing the behaviour of males in two field plots maintained at different population densities, however, we found that high density was directly related to a higher incidence of inactive behaviour. Males perched on creosote ( Larrea tridentata) bushes (their host plant), and certain bushes. Mating behaviour was independent of body size and, while young (<7 days old) males tended to be inactive, neither age nor the time of adult maturation during the season could fully account for the incidence of inactive behaviour among males. Instead, we suggest that the adoption of inactive behaviour resulted partly from aggressive encounters between males.

The contributions of genotype and sex to variation in mating behaviour between geographical subspecies of the bank vole ( Clethrionomys glareolus scheber)

The sexual behaviour of bank voles from the mainland of Great Britain, and from the island of Skomer, differs in a number of respects. Voles from the mainland population show in general greater sexual activity. These variations may be understood as adaptations to ecological differences, particularly in population density. The reciprocal hybrids resemble the mainland population in a number of aspects of their mating behaviour. The possible evolutionary importance of this dominance is discussed. The behaviour of the bank vole is put into the perspective of generalizations made about other mammals. The separate influence of the male and of the female on quantitative variation between the two forms was investigated by studying mating between members of different populations. Some aspects of mating behaviour are shown to be due primarily to the male, others primarily to the female and others to the particular combinations involved. This situation is discussed in relation to the separate action of natural selection on members of each sex.