We examine the causes and consequences of behavioral variation using experimental approaches to integrate endocrinology, evolutionary biology and neurobiology.
Alex Baugh
Associate Professor Swarthmore College
Research
Integrative Behavioral Biology
One stream of our research centers on understanding the forces that generate and maintain individual (co)variation in decision making (e.g., communication and coping behavior) and its physiological regulation (e.g., sensory processing and stress reactivity) in wild animals. We take an ecological approach, testing evolutionary hypotheses in the context of an organism’s natural environment. The types of questions we explore include:
- Which behavioral traits are stable versus plastic, and what are the extrinsic (environmental) and intrinsic (physiological and neural) bases of such variation?
- What are the developmental factors and sensitive periods that sculpt behavioral and physiological variation, and which environmental and experiential factors influence developmental trajectories and impact fitness?
While the study of single traits has proven fruitful, the study of animal behavior has become increasingly interested in understanding higher order traits, including suites of correlated characters. This is essential in order to understand the targets on which natural and sexual selection may act. Therefore we also explore questions such as:
- Do regulatory systems, such as steroid hormones, exert pleiotropic effects and hence generate suites of correlated behavioral traits?
- By manipulating the physiological systems that regulate behavior, can we engineer phenotypes in order to experimentally decompose and thus understand the structure of behavior and the trade-offs organisms face?
In the domain of animal communication, our model systems include acoustic signaling and auditory behavior in anuran amphibians (frogs and toads). We test hypotheses about the physiological basis for reproductive decision making (acoustic signaling and acoustically-guided behavior).
In the domain of behavioral endocrinology, we seek to understand the intrinsic and experience-dependent factors that organize and activate behavioral responses to challenge, such as exposure to environmental and social stressors.
Current Projects
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Previously, I demonstrated that male gray treefrogs in amplexus have substantially higher circulating concentrations of androgens, estrogens and glucocorticoids compared to adjacent solo males. Now, I am collaborating with Dr. Megan Freiler (Post-doc) and Prof. Mark Bee to experimentally test the hypothesis that the motor act of clasping itself drives these increases and correlated hormones, and to understand the neuroendocrine and peripheral mechanistic basis of this effect.
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Working with Mark Bee (UMN) and Chris Leary (Ole Miss) we are attempting to experimentally decompose the independent and interactive effects of glucocorticoids and androgens on male vocal behavior using field experiments in Cope’s grey treefrogs.
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My lab is developing techniques to estimate concentrations of hormones in frogs without the collection of tissues. We are currently using spadefoot toads to establish and validate effective methods for steroid collection, extraction and quantification and we are now applying this non-invasive method to problems in behavioral endocrinology and conservation physiology in the lab and field. Thus far we have determined that brief, non-invasive water borne methods can effectively estimate biologically informative concentrations of multiple steroid hormones in three amphibian species.
Hyla versicolor
Tungara frog
Couch’s Spadefoot
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During my sabbatical I am working with Alex Jordan’s research group in the Collective Behavior department at the Max Planck Institute for Animal Behavior at the University of Konstanz. We are developing techniques and testing hypotheses related to social transmission of hormones via water-borne steroids across a clade of cichlid fishes from Lake Tanganyika.
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Here we are testing the influence of glucocorticoids on female mate choice and how the circulating concentrations of steroids interact with the expression of steroid receptors in the brain to explain behavioral effects.
MN Tamarack Pond
Calling male H. chrysoscelis (MN)
Calling male H. versicolor
Calling male H. chrysoscelis
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This project (CITISENSE), which is led by Wouter Halfwerk aims to uncover the basis (heritable and acquired traits) for differences in urban and forest dwelling tungara frogs. The urban populations (e.g. in Panama City) express more risk-taking behavior compared to their forest counterparts. This multi-institution collaboration aims to identify the source of this population variation, including a look at differences in the hormonal milieu.
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Mating is typically a brief and key life history chapter in a sexually reproducing animal’s life. Because successful reproduction requires a set of essential adaptations that are less important during a non-breeding period, we expect substantial phenotypic remodeling during this transition, and for these shifts to occur in a coordinated fashion (i.e. phenotypic integration). For example, receivers need to be able to detect and discriminate conspecific advertisement signals before choosing a mate and copulating, and thus need a suite of sensory and behavioral adaptations to subserve those tasks. Once a seasonally breeding female has mated, however, these traits may shift in order to support other lifestyle needs.
We are testing this hypothesis of phenotypic integration using wild-caught female Cope’s gray treefrogs (Hyla chrysoscelis) and evaluating how three trait categories shift over the course of a single day following mating: behavioral (phonotaxis), neural (auditory thresholds) and endocrinological (glucocorticoids, testosterone, estradiol); and how these three levels of the phenotype interact.