How animals choose mates is one of the most important questions in biology, because these decisions can shape the evolution of a species. Pressure to select a good mate may be particularly strong when an animal will have only one mate in a lifetime, or survival of infants depends on both parents. This project focuses on the relationship between male testosterone (T), courtship behavior and fathering behavior in the California mouse, Peromyscus californicus. California mice are unusual for mammals because fathers help mothers raise offspring, who cannot survive without their father's presence. Work with fish and birds has shown that females of other species sometimes prefer mates who can signal that they will be good fathers, but it is unknown whether the same is true for mammals. This proposal expands upon previously collected data by the same researchers that show that the amount of T a male releases when he is introduced to a female predicts aspects of his potential as a good father. The goal of the proposed project is to determine whether females can detect the amount of T a male releases during courtship, and if females prefer males who release the most T and advertise this trait using vocal communication. These studies will further an understanding of how species form mating preferences, and strengthen the concept that paternal care can be an important resource for females to consider during mate choice. Moreover, exploring the relationship between T and paternal care in the California mouse will further a more general understanding of how the neuroendocrine system functions to support fathering behavior in mammals, which has the potential to extend to human parenting. Vocal recording techniques from this project will be used in a laboratory module for students enrolled in an undergraduate course in behavioral neuroscience.
How animals choose mates is one of the most important questions in biology, because these decisions can shape the evolution of a species. Pressure to select a good mate may be particularly strong when an animal will have only one mate in a lifetime, or survival of infants depends on both parents. This project focused on the relationship between male testosterone (T), courtship behavior and fathering behavior in the California mouse, Peromyscus californicus. California mice are unusual for mammals in that fathers and mothers raise offspring together, and offspring do not survive without their father's presence. This research upon previously collected data by the same researchers that show that the amount of T a male releases when he is introduced to a female predicts aspects of his future fathering abilities. We tested (1) whether male T-response is a consistent individual trait, 2) whether female California mice prefer to mate with males who have higher T-responses. We found that T-response is highly consistent within an individual, but variable across individuals. We showed that females do not prefer males with higher T (although females did spend more time investigating males with higher T), but that reproductive success of a pair depended on whether the female had shown a preference for her male before they were mated. Interestingly, whether another female had preferred the male did not matter for reproductive success; in other words, some aspect of compatibility between individuals was more important that T levels. This research expanded our understanding of how the neuroendocrine system functions to support social behavior in mammals, which has the potential to extend to human mate choice and parenting. One possibility that these findings raise is that how mates interact with one another, either physiologically (the immune system, for example) or behaviorally ( trading-off parenting responsibilities, responding to each others' behavioral signals), is an important predictor of mate attraction and reproductive success as a bonded pair.
