Consistent individual differences in behavior [i.e., behavioral types (BTs)], are common across the animal kingdom. Consistency can make behavior an adaptive trait for mate choice decisions. Here, we present a conceptual framework to explain how and why females might evaluate a male's BT before mating. Because BTs are consistent across time or context, a male's BT can be a reliable indicator of his potential to provide direct benefits. Heritable BTs can enable informed mate choice via indirect benefits. Many key issues regarding patterns of mate choice, including sensory biases, context dependence, and assortative mating apply to BT-dependent mate choice. Understanding the relationship between BTs and mate choice may offer insights into patterns of variation and consistency common in behavioral traits.
BTs and Mate ChoiceMate choice is often a key factor influencing the evolution of traits [1,2]. While sexual selection via mate choice likely has a special role as a major explanation for highly elaborated ornaments, it is not only important for explaining exaggerated, sex-specific traits. A new insight is that the choosy sex (typically females) may also select a mate based on their own and their potential mate's behavioral type (BT) (see Glossary); for example, boldness, aggressiveness, exploratory tendency, or sociability [3]. An individual is said to have a BT if its behavior is consistent across time or contexts (e.g., an individual that is more aggressive than another in a foraging context, also tends to be more aggressive in the future and/or more aggressive in a mating context) [4]. If males have consistent BTs, then male behavior observed by a female at one time and context (e.g., during courtship) provides information about his likely behavior in the past and future (e.g., during parental care). Importantly, the time scale of this correlation is not part of the definition for either human or animal personalities [4,5]. More persistent BTs (e.g., over a lifetime) presumably have greater potential to be impactful, particularly for species with long-term mating associations, but even short-term consistency (e.g., from courtship to nesting or parental behavior a few weeks later) can be important [6][7][8].With regard to mechanisms of adaptive mate choice, correlations between a potential mate's past, present, and future behaviors may determine the quality and quantity of expected direct benefits that he can provide (e.g., nuptial gifts, territory, or parental care) [3]. Within a breeding season, BTs allow a female to predict a male's future behavior towards her and her offspring, which may be particularly important for species that have paternal care, including territory defense and provisioning [9,10]. While consistency to the next breeding season is not necessarily important for all species, species that engage in long-term pair bonds may rely more heavily on BTs to determine long-term compatibility [11]. Furthermore, given that BTs are heritable (about half of BT variation is attributable to additive geneti...