Mating Success

Dominance assessment is important in mating competition across a variety of species, but little is known about how individuals’ own quality affects their assessment of potential rivals. We conducted two studies to test whether men’s own dominance affects their attentiveness to a putative dominance signal, vocal masculinity, when assessing competitors. Study I examined dominance ratings made by men in relation to their self-rated physical dominance. Study II examined dominance ratings made by men in relation to objective measures of their physical dominance, including size, strength, testosterone, and physical aggressiveness. Vocal masculinity strongly affected dominance ratings, but a man’s own dominance did not alter his attention to vocal masculinity when assessing dominance. However, men who rated themselves high on physical dominance rated the voices of other men lower on dominance and reported more sex partners (study I). Men with intermediate testosterone concentrations rated the voices of other men lower on dominance (study II). These results confirm the effect of vocal masculinity on dominance perceptions, provide further evidence that dominance is relevant to mating success, and shed new light on how men assess the dominance of rivals and potential allies. Our results suggest that attention to dominance signals may depend less on the observer’s own dominance in species with coalitional aggression, where individuals must assess others not only in relation to themselves but also in relation to each other. Among men, the effect of a deep, masculine voice on perceptions of dominance appears to be robust and unmediated by the formidability of the listener.

In mammals, when females are clumped in space, male access to receptive females is usually determined by a dominance hierarchy based on fighting ability. In polygynandrous primates, as opposed to most mammalian species, the strength of the relationship between male social status and reproductive success varies greatly. It has been proposed that the degree to which paternity is determined by male rank decreases with increasing female reproductive synchrony. The priority-of-access model (PoA) predicts male reproductive success based on female synchrony and male dominance rank. To date, most tests of the PoA using paternity data involved nonseasonally breeding species. Here, we examine whether the PoA explains the relatively low reproductive skew in relation to dominance rank reported in the rhesus macaque, a strictly seasonal species. We collected behavioral, genetic, and hormonal data on one group of the free-ranging population on Cayo Santiago (Puerto Rico) for 2 years. The PoA correctly predicted the steepness of male reproductive skew, but not its relationship to male dominance: the most successful sire, fathering one third of the infants, was high but not top ranking. In contrast, mating success was not significantly skewed, suggesting that other mechanisms than social status contributed to male reproductive success. Dominance may be less important for paternity in rhesus macaques than in other primate species because it is reached through queuing rather than contest, leading to alpha males not necessarily being the strongest or most attractive male. More work is needed to fully elucidate the mechanisms determining paternity in rhesus macaques.

Females of several acoustic insects and anurans have recently been shown to orient preferentially to the leading of two identical male calls presented in close succession. We studied this phenomenon via two-choice phonotaxis trials in the neotropical katydidNeoconocephalus spizaand found that females avoided male calls occurring during an interval beginning immediately after the onset of a leading call. This avoidance occurred whether or not the following call was overlapped by the leader, indicating that the mechanism of preference for leading calls may represent a psychoacoustic precedence effect rather than simple call masking. We also found that females preferred leading calls as long as the amplitude of the following call was not more than 2dB higher than the leader. Under certain circumstances, preferences for leading calls remained when females were presented with a sequence of four calls. Thus, preferences for leading calls probably influence a male’s attractiveness and mati...

The extent to which active female mating preferences influence male reproductive success in mammals is unclear, particularly for promiscuously breeding species like chimpanzees (Pan troglodytes). Previous studies from multiple long-term study sites have shown that female chimpanzees mate more restrictively around ovulation, and this has been taken as evidence for female choice. However, none of these studies rigorously evaluated the alternative hypothesis that restrictive mating results not from unconstrained choice, but in response to coercive mate guarding, in which males use punishment and intimidation to reduce female promiscuity and promote their own mating interests. Nor did they consider evidence for the potential genetic or phenotypic benefits that females might be choosing. Using 11 years of data from the Kanyawara community in Kibale National Park, Uganda, we previously demonstrated that males achieve elevated mating success with those females toward whom they direct high levels of aggression. Here we extend those findings to show that even female copulatory approaches, which have previously been attributed to female choice, are correlated with male aggression. Specifically, individual females at our site initiated periovulatory copulations most frequently with the males who were most aggressive toward them throughout their cycles. Those males showed high rates of aggression toward females throughout estrus, despite achieving high copulation rates, demonstrating a continuing conflict of interest over the exclusivity of mating access. Because sexual coercion is potentially widespread in primates and other mammals, our results stress the importance of considering the influence of male aggression in studies of female choice.

The relationship between male dominance rank and reproductive success has been a topic of interest since the beginning of primatology. From a theoretical point of view the existence or absence of this relationship has great implications with respect to the meaning of dominance rank and more general of the social relationships between individuals within social groups. Until fairly recently mating behaviour has been used as an indicator of reproductive success, but these two variables need not be correlated. The relations between mating success, reproductive success, and dominance rank indicate whether selective mating is involved (different mating partners at different phases of fertility, for example through male contest or female choice). With the development of genetic techniques to determine reproductive success directly, it has now become possible to investigate these relations. In our study on wild long-tailed macaques (Macaca fascicularis) we find a relatively strong correlation between rank and reproductive success which is attributable to selective mating by the alpha male during fertile periods of the females. In most previous studies no such clear results have been obtained, and we discuss the differences in outcome in relation to the study conditions, group sizes, and possible differences between species in terms of reproductive strategies.