My research addresses fundamental questions in evolutionary biology via the study of links among organismal form, function, behavior, survival, and reproductive success. More specifically, I try to answer three inter-related questions: (1) how do hormones link animals to their biotic and abiotic environments through the regulation of performance traits important to fitness? (2) how does sexual selection shape physiological traits? and (3) what is the ecological significance of locomotor performance and how does selection act on the physiological traits underlying it? These components of my research explore how morphology and physiology interact with, and are shaped by, the environment through selection on their functional integration. Most of my research is conducted on lizards, but I also work with stalk-eyed flies and spiders to generalize how natural and sexual selection drive the evolution of form and function.

Physiological determinants of performance. I am using experimental approaches to determine whether and how steroid hormones, training, and diet (and their interactions) affect muscle physiology and performance capacity in lizards. This involves experimental removal, replacement, and supplementation of hormones, along with different training regimes and diets with varied protein content.

How endocrine systems regulate social behavior. I am studying Caribbean Anolis lizards to test what components of endocrine regulation are responsible for species differences in social behavior and life history strategy. To do this I am measuring circulating levels of steroid hormones in wild lizards, in addition to comparing target tissue sensitivity to these hormones. The main question is, has similar endocrine function re-evolved independently to regulate behavior, or are there multiple endocrine routes to the same behavioral end?

Direct and indirect effects of sexual selection on performance. I study lizards in the wild to determine what mating advantage performance capacity may give to better performers. (direct effects). I study stalk-eyed flies to test how a sexually selected ornament results in the evolution of traits that offset performance costs of the ornament (indirect effects).

• Husak, J. F., G. Ribak, G. S. Wilkinson, and J. G. Swallow. Sexual dimorphism in wing beat frequency in relation to eye span in stalk-eyed flies (Diopsidae). In press, Biological Journal of the Linnean Society. 
• Husak, J. F., J. P. Henningsen, B. Vanhooydonck, and D. J. Irschick. A performance-based approach to studying costs of reliable signals. In D. Irschick, M. Briffa, and J. Podos, Eds. Animal Signaling; Functional and Evolutionary Perspectives, John Wiley & Sons. In press.
• O’Connor, J. L., L. D. McBrayer, T. E. Higham, J. F. Husak, I. T. Moore, and D. C. Rostal. Effects of training and testosterone on muscle-fiber types and locomotor performance in male six-lined racerunners (Aspidoscelis sexlineata). Physiological and Biochemical Zoology 84:394-405.
• Husak, J. F., G. Ribak, G. S. Wilkinson, and J. G. Swallow. 2011. Compensation for exaggerated eyestalks in stalk-eyed flies (Diopsidae). Functional Ecology 25:608-616.
• Husak, J. F., and J. G. Swallow. 2011. Compensatory traits and the evolution of male ornaments. Behaviour 148:1-29.
• Lind, C. M., J. F. Husak, C. Eikenaar, I. T. Moore, and E. N. Taylor. 2010. The relationship between plasma steroid hormone concentrations and the reproductive cycle in the northern Pacific rattlesnake, Crotalus oreganus. General and Comparative Endocrinology 166:590-599.
• Pruitt, J. N., and J. F. Husak. 2010. Context-dependent use of running speed in funnel-web spiders from divergent populations. Functional Ecology 24:165-171.
• Huyghe, K., J. F. Husak, R. Van Damme, M. Molina-Borja, and A. Herrel. 2010. Effects of testosterone on morphology, whole-animal performance and muscle mass in a lizard. In press, Journal of Experimental Zoology 313A:9-16.
• Husak, J. F., S. D. McCormick, D. J. Irschick, and I. T. Moore. 2009. Hormonal regulation of whole-animal performance: implications for selection. Integrative and Comparative Biology 49:349-353.
• Husak, J. F., and D. J. Irschick. 2009. Steroid use and human performance: lessons for integrative biologists. Integrative and Comparative Biology 49:354-364.
• Huyghe, K., J. F. Husak, A. Herrel, Z. Tadi?, I. T. Moore, R. Van Damme, and B. Vanhooydonck. 2009. Relationships between hormones, physiological performance and immunocompetence in a color-polymorphic lizard species, Podarcis melisellensis. Hormones and Behavior 55:488-494.
• Husak, J. F., A. K. Lappin, and R. A. Van Den Bussche. 2009. The fitness advantage of a high performance weapon. Biological Journal of the Linnean Society 96:840-845.
• Husak, J. F., D. J. Irschick, J. P. Henningsen, K. S. Kirkbride, S. P. Lailvaux, and I. T. Moore. 2009. Hormonal response of male green anole lizards (Anolis carolinensis) to GnRH challenge. Journal of Experimental Zoology 311A:105-114.
• Husak, J. F., and I. T. Moore. 2008. Stress hormones and mate choice. Trends in Ecology and Evolution 23:532-534.
• Husak, J. F., S. F. Fox, and R. A. Van Den Bussche. 2008. Faster male lizards are better defenders not sneakers. Animal Behaviour 75:1725-1730.
• Husak, J. F., and S. F. Fox. 2008. Sexual selection on locomotor performance. Evolutionary Ecology Research 10:213-228.
• Irschick, D. J., J. J. Meyers, J. F. Husak, and J. F. Le Galliard. 2008. How does selection operate on whole-organism functional performance capacities? A review and synthesis. Evolutionary Ecology Research 10:177-196.
• Irschick, D., J. K. Bailey, J. A. Schweitzer, J. F. Husak, and J. J. Meyers. 2007. New directions for studying selection in nature: studies of performance and communities. Physiological and Biochemical Zoology 80:557-567.
• Husak, J. F., D. J. Irschick, J. J. Meyers, S. P. Lailvaux, and I. T. Moore. 2007. Hormones, sexual signals and performance of green anole lizards (Anolis carolinensis). Hormones and Behavior 52:360-367.
• Bergeron, C. M., J. F. Husak, J. M. Unrine, C. S. Romanek, and W. A. Hopkins. 2007. Influence of feeding ecology on blood mercury concentrations in four turtle species. Environmental Toxicology and Chemistry 26:1733-1741.
• Husak, J. F. 2006. Does survival depend on how fast you can run or how fast you do run? Functional Ecology 20:1080-1086.
• Husak, J. F., S. F. Fox, M. B. Lovern, and R. A. Van Den Bussche. 2006. Faster lizards sire more offspring: sexual selection on whole-animal performance. Evolution 60:2122-2130.
• Husak, J. F. 2006. Do female collared lizards change field use of maximal sprint speed capacity when gravid? Oecologia 150:339-343.
• Husak, J. F., and S. F. Fox. 2006. Field use of sprint speed by collared lizards (Crotaphytus collaris): compensation and sexual selection. Evolution 60:1888-1895.
• Lappin, A. K., Y. Brandt, J. F. Husak, J. M. Macedonia, and D. J. Kemp. 2006. Gaping displays reveal and amplify a mechanically-based index of weapon performance. American Naturalist 168:100-113.
• Husak, J. F., J. M. Macedonia, S. F. Fox, and R. C. Sauceda.  2006. Predation cost of conspicuous male coloration in collared lizards (Crotaphytus collaris): an experimental test using clay-covered model lizards. Ethology 112:572-580.
• Husak, J. F., and M. N. Rouse. 2006. Population variation in escape behavior and limb morphology of collared lizards (Crotaphytus collaris) in Oklahoma. Herpetologica 62:156-163.
• Husak, J. F. 2006. Does speed help you survive? A test with collared lizards of different ages. Functional Ecology 20:174-179.
• Husak, J. F., A. K. Lappin, S. F. Fox, and J. A. Lemos-Espinal. 2006. Bite-force performance predicts dominance in male Venerable Collared Lizards (Crotaphytus antiquus). Copeia 2006:301-306.
• Peterson, C. C., and J. F. Husak. 2006. Locomotor performance and sexual selection: individual variation in sprint speed of collared lizards (Crotaphytus collaris). Copeia 2006:216-224.
• Lappin, A. K., and J. F. Husak. 2005. Weapon performance, not size, determines mating success and potential reproductive output in the collared lizard (Crotaphytus collaris). American Naturalist 166:426-436.
• Macedonia, J. M., J. F. Husak, Y. M. Brandt, A. K. Lappin, and T. A. Baird. 2004. Sexual dichromatism and color conspicuousness in three populations of collared lizards (Crotaphytus collaris) from Oklahoma. Journal of Herpetology 38:340-354.
• Husak, J. F. 2004. Signal use by collared lizards, Crotaphytus collaris: the effects of familiarity and threat. Behavioral Ecology and Sociobiology 55:602-607.
• Husak, J. F., J. K. McCoy, S. F. Fox, and T. A. Baird. 2004. Is coloration of juvenile male collared lizards (Crotaphytus collaris) female mimicry?: an experimental test. Journal of Herpetology 38:156-160.
• Husak, J. F., and S. F. Fox. 2003. Adult male collared lizards (Crotaphytus collaris) increase aggression towards displaced neighbours. Animal Behaviour 65:391-396.
• Husak, J. F., and S. F. Fox. 2003. Spatial organization and the dear enemy phenomenon in adult female collared lizards, Crotaphytus collaris. Journal of Herpetology 37:211-215.
• Husak, J. F., and E. N. Ackland. 2003. Foraging mode of the reticulate collared lizard, Crotaphytus reticulatus. Southwestern Naturalist 48:282-286.
• Husak, M. S. and J. F. Husak. 2002. Low frequency of site fidelity by golden-fronted woodpeckers. Southwestern Naturalist 47:110-114.
• Husak, J. F., and J. K. McCoy. 2000. Diet composition of the collared lizard (Crotaphytus collaris) in west-central Texas. Texas Journal of Science 52:93-100.