Michaela Hau Assistant Professor in Ecological and Evolutionary Biology, Princeton University Title Testosterone and the evolution of vertebrate life-history trade-offs Abstract Aggressive behavior serves to establish dominance relationships among animals and can generate fitness benefits by ensuring access to resources. In the majority of male non-tropical vertebrates, circulating concentrations of testosterone increase during the breeding season to promote the expression of aggressive behavior. However, in birds recent comparative studies documented that tropical species have lower peak testosterone concentrations during the breeding season compared to non-tropical species, and that seasonal fluctuations in testosterone can be slight or even absent. Detailed experimental studies in one species, the year-round territorial spotted antbird (Hylophylax n. naevioides) suggest that testosterone can regulate aggressive behavior even in a species that has low circulating concentrations of this hormone, as the pharmacological manipulation of testosterone actions did modulate aggressive behavior. However, the regulation of aggressive behavior by testosterone differs from what is known for most temperate birds in at least two ways. First, instead of generally increasing circulating testosterone concentrations during the breeding season, male spotted antbirds maintain low plasma testosterone concentrations and only increase secretion during high-intensity aggressive interactions lasting longer than two hours. Second, while in many temperate-zone male birds the seasonal regulation of testosterone concentrations and brain sex steroid receptor expression are temporally linked, in male spotted antbirds the seasonal regulation of circulating testosterone concentrations and sex steroid receptors in certain brain areas is temporally uncoupled. Such inter- and intraspecific variation in the control of certain traits by testsosterone will be discussed with respect to recent ideas that testosterone plays an important role in mediating vertebrate life-history trade-offs. CV Professional experience 1995-1998 Research Assistant, Dept. Zool., University of Washington. 1998-1999 Research Specialist, Dept. Ecology, Ethology and Evolution, University Illinois at Urbana-Champaign. 1999-2000 Adjunct Assistant Professor, Dept. Ecology, Ethology & Evolution, University Illinois. Since 2000 Assistant Professor, Dept. Ecological & Evolutionary Biology, Princeton University. Faculty Associate in: Neuroscience Program at Princeton University, Program in Latin American Studies at Princeton University, and Princeton Institute for International and Regional Studies. Education 1983-1991 Study of Biology (Zoology, Botany and Pharmacology), Johann-Wolfgang-Goethe-University in Frankfurt and Ludwig-Maximilians-University in Munich. 1991 Diploma in Biology, Ludwig-Maximilians-University Munich. 1995 Ph.D. in Zoology, Ludwig-Maximilians-University Munich. 1995-1998 Post-doctoral research at University of Washington, Seattle. Host: Prof. J.C. Wingfield; and at Smithsonian Tropical Research Institute, Panama. Hosts: A.S. Rand and N.G. Smith. Recent publications Perfito, N., Bentley, G.E. & Hau, M. (2006) Tonic activation of brain GnRH immunoreactivity despite reduction of peripheral reproductive parameters in opportunistically breeding zebra finches. Brain Behav. Evol. 67: 123-134. Martin, L.B., Han, P., Kwong, J. & Hau, M. (2006) Cutaneous immune activity varies with physiological state in female house sparrows (Passer domesticus). Physiol. Biochem. Zool., 79(4): 775-783. Canoine, V., Fusani, L., Schlinger, B.A. & Hau, M. (2006) Low sex steroids, high steroid receptors: increasing the sensitivity of the non-reproductive brain. J. Neurobiol., in press. Millet, S., Bennett, J., Lee, K.A., Hau, M. & Klasing, K.C. (2006) Quantifying constitutive immunity in birds. Dev. Comp. Immunol., in press. Spinney, L.H., Bentley, G.E. & Hau, M. (2006) Endocrine correlates of alternative phenotypes in the white-throated sparrow (Zonotrichia albicollis). Horm. Behav., in press. Wikelski, M., Martin, L.B., Robinson, M.T., Robinson, N.D., Scheuerlein, A., Hau, M. & Gwinner, E. Avian circannual clocks: adaptive significance and and possible proximate control by energy turnover. Phil. Trans. R. Soc. B, in press. Institution address Michaela Hau Department of Ecology and Evolutionary Biology 307 Guyot Hall, Princeton University Princeton, NJ 08544, USA Phone: +1 (609) 258-3508 Fax: +1 (609) 258-7892 Hau@princeton.edu http://www.princeton.edu/%7Ehau/