Mating Tactics and Strategies

Abstract

Alternative mating tactics and strategies are sex-limited reproductive polyphenisms and polymorphisms. They appear as discontinuous distributions of behavioral, developmental, or morphological traits, expressed among the members of one sex, and they occur within the context of reproductive competition. Polymorphic mating phenotypes are usually found in species in which sexual selection is strong, that is, in species in which the variance in fitness within one or both sexes is large. Polyphenisms and polymorphisms tend to be more obvious in the sex with greater variance in fitness. Thus, like many sexually selected traits, alternative mating tactics and strategies are expressed more often in males than in females, although polymorphic females also exist, especially when variance in female fitness is large. While classification schemes vary, alternative mating “tactics” usually describe flexible behavioral or developmental phenotypes that may change over brief periods of time, whereas alternative mating “strategies” generally describe less flexible morphological traits. The tactic-strategy dichotomy appears to have been identified to capture observed variation in behavior vis-à-vis morphology as studies documenting mating polymorphisms began to accumulate, and to stimulate future research. However, this typological framework has led to vigorous debate about whether genetic variation underlies observed polymorphic phenotypes and the nature of the evolutionary processes by which these polymorphisms may persist in the wild. Although the tactics-strategy dichotomy persists in even the most recent literature, accumulating results suggest that the range of mating polymorphisms, while variable in the circumstances in which they are favored, as well as in the timing and reversibility of their expression, are shaped by similar evolutionary processes, notably, negative frequency dependent selection; that is, when one tactic or strategy becomes common, the alternative has a fitness advantage. This article first considers fundamental literature describing mating polymorphisms beginning with observations by Darwin and his contemporaries. It then identifies books and collections of literature in which the subject of mating polymorphism and sex-specific polyphenisms are considered at length or with high frequency. Based on this framework, it next outlines contributions to these conceptual frameworks that have arisen to explain what mating polymorphisms are, why they exist, and how they persist. Lastly, it surveys contributions focused on the inheritance, expression, and evolution of mating polymorphisms, as well as specific considerations relating to active areas of current research.