Dominance Rank, Copulatory Behavior, and Differential Reproduction

Abstract

The view that high social rank is associated with high levels of both copulatory behavior and the production of offspring is widespread in the study of animal behavior. In order to demonstrate the validity of this hypothesis it is necessary first to resolve ambiguities in the concept of dominance and to assign ranks by means of valid procedures. Second, copulatory behavior must be properly sampled, measured, and related to rank. Finally, it must be demonstrated that rank and increased copulatory behavior actually lead to increased reproduction. Each step in this process entails conceptual and methodological difficulties. There have been many studies of rank and copulatory behavior, fewer of rank and differential reproduction, and very few of rank, copulatory behavior, and differential reproduction. The consistency of results obtained varies with taxon; results of particular consistency appear in studies of carnivores and ungulates. Both the concept of dominance and the validity of the hypothesis relating it to copulatory behavior and to differential reproduction appear viable for at least some species, although the body of data relating rank to both copulation and differential reproduction remains minimal.

Dominant and subordinate behaviour of captive brushtail possums (Trichosurus vulpecula)

“…Potential advantages include greater annual reproductive output, longer reproductive life, and higher survival of offspring (Dewsbury 1982). Some of these advantages have been demonstrated previously for other groups of wild animals, including fish, birds, rodents, carnivores, lagomorphs, ungulates, and primates (Dewsbury 1982;Liberg 1983;Cowlishaw & Dunbar 1991;Kodric-Brown 1992;Hirotani 1994;Owens & Owens 1996), but not for wild possums. In captivity, with restricted space but ample food, breeding of subordinate males, but not subordinate females, can be prevented by dominant possums (Oldham 1986; this study).…”

“…Dominance status is positively related to age and/or body weight within gender (Winter 1976;Oldham 1986) but females, the lighter sex, are generally dominant over males (Jolly 1976;Winter 1976;Cowan 1982;Oldham 1986). The function of dominance hierarchies in possums has not been determined, but in many species dominant males copulate more frequently, and dominant females leave more offspring, than do subordinates (Dewsbury 1982;Liberg 1983;Cowlishaw & Dunbar 1991;Kodric-Brown 1992;Hirotani 1994;Owens & Owens 1996).…”

Seasonality in squirrel monkeys (Saimiri sciureus): Social facilitation by females

“…Perhaps even more surprising is the finding that subordinate females were more likely to conceive than dominant females. This contradicts the well-accepted notion that social dominance functions to enhance reproductive success for dominant individuals [11]. Dominant females in many species have been reported to breed exclusively, or at a higher rate, than subordinates [1,4,16,17,43].…”

The Early Development of Gender Differences

“…However, finding a mate is only relevant to sexual reproduction. In some species, finding a mate may involve travel over long distances, displays of health or beauty, physical conflict with others who are seeking mates, or coercion of the potential mates themselves (Bateman 1948, Clutton-Brock & Parker 1992, Dewsbury 1982. For reasons that are not fully understood (Kokko et al 2006, Wade & Shuster 2002, parental investment activities of many kinds are often, but not always, enacted by one physical form, which is also often the form with larger gametes, called female, and mating activities by another physical form, often with smaller, more motile gametes, called male.…”