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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.

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Copulatory patterns of muroid rodents provide an ideal locus for comparative behavioral research. Such patterns are highly stereotyped within and between the individuals of a given species, variable across species, readily elicited in the laboratory, and of great biological significance. Detailed behavioral comparisons of a broad range of muroid species have revealed extensive behavioral diversity that was not anticipated from research confined to laboratory rats. Various muroid species display postejaculatory compulations without sperm transfer, locking, thrusting, and other behavioral patterns. This behavioral diversity appears not to be the result of a simple linear pattern of evolutionary history. Rather, patterns appear to have evolved repeatedly in response to particular selective pressures acting on particular species. While understanding of the adaptive significance of these behavioral patterns remains rudimentary, important beginnings have been made.

I introduce the term "Darwin-Bateman Paradigm" to include several proposals stemming from the writings of Charles Darwin and A. J. Bateman, including the notions that (a) male reproductive success is more variable than that of females, (b) males gain more in reproductive success from repeated matings than do females, and (c) males are generally eager to mate and relatively indiscriminate whereas females are more discriminating and less eager. I trace this paradigm from Darwin's The Descent of Man through Bateman's research and beyond. I try to clarify the terminology used in applying Bateman's results and discuss both the impact and the criticisms the paradigm has engendered. I then broaden the context of the Darwin-Bateman Paradigm to show related conceptions in disparate fields that evolved in parallel with it. I conclude that gender stereotypes appear to have influenced these conceptions. The paradigm has been of great heuristic value but is in need of further empirical investigation in view of numerous exceptions to these general rules.

The degree of novelty of both mating partner and mating situation can be of great importance to the sexual behavior of nonhuman animals under some circumstances. The "Coolidge effect" can be defined as the restoration of mating behavior in males that have reached sexual satiation with one female and show a restoration of mating behavior when the original female is replaced with a novel female. Information on the Coolidge effect has recently been used in extrapolations to human behavior, in attempts to predict monogamy in different species, and in a sociobiological context. The literature on the Coolidge effect is reviewed critically and various complexities and inconsistencies are discussed. Studies conducted utilizing different paradigms, including the Coolidge effect, changes of female prior to satiety, multifemale tests, between-test changes of female, changes of environment, and choice situations, should be consistently differentiated. Results differ as a function of species, paradigm, and testing conditions.

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