Catherine A Marler - US grants

l propose to develop an animal system for the study of hormonal control of rapid changes in reproductive behaviors that occur in response to social conditions. The frog, Acris crepitans, is an ideal model in that 1) individuals can switch rapidly between discrete categories of mating behaviors, 2) behavioral switching can be experimentally induced through playbacks of calls of larger males, and 3) behavioral and hormonal studies can be performed under natural conditions. The goals of this series of studies are threefold. The first is to discover whether a previously determined correlation between intrasexual variation in mating behavior with the neuropeptide arginine vasotocin (AVT) reflects a causal interaction (i.e. do changes in AVT control rapid changes in mating behavior?). This will be accomplished using hormonal manipulations under natural conditions. The second is to examine brain hormonal changes (using immunocytochemistry and image analysis) in response to social interactions represented by acoustic signals of both dominant and subordinate individuals. The third is to begin examining the role of steroid hormones in rapid changes in mating behavior by measuring steroid levels using radioimmunoassays and, if time permits, by manipulating steroid levels. These studies will aid in our understanding of potential hormonal mechanisms involved in controlling intrasexual variation in vertebrate behavior, as well as how social conditions may influence reproductive' behaviors in individuals through effects on hormonal systems within the brain. Neuropeptide studies of non-humans have provided exciting information on hormonal involvement if social interactions, but as yet, many aspects of this remain poorly understood. The proposed studies can provide predictive models that may be used to evaluate biochemically based reproductive disorders in humans.

PI: Marler, C. IBN-973309 Behavior plays a crucial role in interactions between an animal's internal and external environments. While significant progress has been made in understanding how social interactions can influence adult hormone levels, we know little about the impact of the early social environment on behavior, particularly factors influencing aggression. The PI proposes to investigate the plasticity in behavior in response to significant changes in parental behavior, as well as the physiological mechanisms underlying such plasticity. To examine the effects of both paternal and maternal effects she proposes to work with Peromyscus mice because it is one of the few mammalian model systems in which males make significant contributions to raising the young and also because there is considerable variation among the different species of Peromyscus. The PI will alter levels of parental care by allowing offspring of one species to be raised by the parents of the other species. If this causes changes in aggressive and parental behavior of the offspring once they have matured, then she will examine physiological underpinnings for these changes in behavior. The neuropeptide arginine vasopressin and the steroid hormone testosterone will be studied because these are important biochemicals influencing social interactions of adults, including aggressive interactions and parental behavior. These studies will allow testing of the plasticity of vasopressin both within and between species in response to changes in the social and hormonal environments. A theme that runs through the PI's research is the integration of several different scientific fields. This is an approach which she employs in her teaching as well. The PI uses animal behavior to introduce basic concepts of biology to psychology students and emphasize how animal studies contribute to our understanding of physiological mechanisms influencing human behavior. PROJECT SUMMARY 3

aggression; neuroendocrine system; paternal behavior; animal colony; Primates; behavioral /social science research tag;

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.

When an individual animal interacts with another individual, it has a physiological response. The researchers are trying to understand how physiological responses can influence current and future behavior. Other studies have shown that hormones, such as testosterone, can increase after a social interaction. An important question is whether this hormone release can influence future behavior. Because some hormones can result in a positive, rewarding response, a preference for a location can form in response to the release of a hormone such as testosterone. Thus, any male-male or male-female interaction that results in the release of testosterone may induce an individual to seek out that location repeatedly. Hormone release may therefore influence how individuals use space through the development of preferences for specific locations. This research investigates, for the first time, the natural function of the reward-like properties of testosterone related to the development of preferences for specific locations. This research may reveal a new mechanism, testosterone pulses, for responding rapidly to adapt to changing social conditions associated with specific locations.

The researchers use conditioned place preference development in response to testosterone injections to provide insight into the mechanisms balancing the different social demands of a monogamous and territorial species, the biparental California mouse. The hypothesis is that testosterone pulses induce spatial distributions appropriate for the social demands of the environment and, in turn, alter context appropriate behaviors in the form of paternal and territorial behavior, pair bond maintenance, mate advertisement and mate-attendance. The testosterone-induced spatial distribution may influence behavior only through location or may further amplify and alter social interactions. Within this framework, the researchers test questions in both simple and complex environments. They examine complex aspects of testosterone-modified social interactions by assessing acoustic communication in the field and laboratory. The researchers propose to examine three aims to address the function of T pulses and resulting effects on conditioned place preferences and social behavior for focal pair-bonded males and their mates (Aim 1a), focal male interactions with pups (Aim 1b), focal male interactions with a female intruder (Aim 2), and focal male interactions with a male intruder (Aim 3). This research will create a stimulating and collaborative student-training environment with unique experiences that integrate behavioral endocrinology studies in the field and laboratory. The collaboration between a midwestern R1 and small southern research institution with fieldwork conducted at the Hastings Natural History Reserve in California, will facilitate wide dissemination of expertise across researchers and students, including STEM URM students. The project will be integrated with a successful 10-year old outreach program called "Bats and Mice in Your Backyard." Two software packages are being developed to automate the analysis of ultrasonic vocalizations and mouse behavior from thermal videos collected in the field and will be made available under an open source license