Mating system as a possible driver of behavioral diversity in Peromyscus

Identifying mechanisms underlying behavioral variation is important for understanding ecological and evolutionary processes. Comparative studies can help test hypotheses about the adaptive value of behaviors. Pace of life history and mating systems are broad factors hypothesized to drive species differences in behaviors. We tested these hypotheses using several Peromyscus species from lab stocks that varied in predicted life history and level of monogamy. We predicted that species with faster life histories would be more bold, active, and neophilic, and that these traits would also be positively correlated at the individual level. We further predicted that there would be greater sex differences in behaviors in non-monogamous, more sexually dimorphic species and that sociability would be more highly correlated with other behavioral traits in monogamous than in non-monogamous species. Counter to predictions, we found that larger stocks (with slower paces of life history) tended to be bolder, and that stock size was not associated with differences in activity, neophilia, or sociability. There was greater sexual differentiation in non-monogamous species in sociability, but not in other behaviors. Monogamous species were generally more sociable, and this was especially pronounced in male mice. Monogamous species showed a positive association between boldness and activity, while non-monogamous species showed a positive association between boldness and neophilia. A negative association between neophilia and sociability was stronger in species predicted to be monogamous. Thus, the pace-of-life-history syndrome hypothesis was not supported in this study, but mating system differences could help drive behavioral diversity. Significance statement Social system and pace of life history are two factors hypothesized to drive evolution of behavioral diversity, both between and within populations. We examined whether behavioral variation in several species of Peromyscus mice was associated with either of these factors. Larger species, with slower life histories, were potentially bolder. Monogamous species were generally more social (attracted to other individuals), especially when comparing males, and males and females differed more in this trait in non-monogamous species. The correlations among boldness, response to novelty, and sociability were also different between mating systems. These results do not support predictions from pace-of-life history hypotheses, but they suggest that the evolution of different mating systems is associated with systematic behavioral differences across these related species.