Jerry F. Husak
University of South Dakota
jerry.husak "at" usd.edu
GENERAL RESEARCH INTERESTS: Evolutionary ecology, behavioral ecology, ecomorphology, sexual selection, herpetology
CURRENT RESEARCH: I am a postdoctoral researcher at the University of South Dakota, working with John Swallow, investigating the performance and survival costs (if any!) of exaggerated secondary sexual structures in stalk-eyed flies. Whereas my previous research has focused on how sexual selection favored increased locomotor performance, my current work with stalk-eyed flies examines whether sexually selected traits (i.e., eye stalks) have locomotor performance, and hence fitness, costs. Currently, my postdoctoral work focuses on two main projects:
(1) Signal reliability and maintenance costs - do bigger eyestalks increase mortality of male stalk-eyed flies?: I am conducting mesocosm studies of stalk-eyed flies and a jumping spider predator to determine if males suffer higher mortality than females, as well as if males with bigger eyestalks suffer higher predation than males with smaller eyestalks.
(2) Compensation for male signals - wing shape evolution in stalk-eyed flies: I am using geometric morphometric techniques to determine if sexual dimorphism in wing shape has coeveolved with sexual dimorphism in eyespan among stalk-eyed flies in the genera Sphyracephala, Diopsis, Diasemopsis, and Teleopsis. Changes in wing size and shape may help males compensate for the aerodynamic changes associated with exaggerated eyestalks in dimorphic species. To compliment the comparative study, I am also examining wing shape changes in lines of Teleopsis dalmanni artificially selected for short and long eyestalks.
RESEARCH FOCUS: The goal of my research is to understand the evolution of organismal form, function, and behavior in an ecological context. In particular, my work emphasizes the study of links among whole-animal performance traits, behavior, survival, and reproductive success in natural populations. My research program focuses on four inter-related areas:
(1) Integrating functional, behavioral, and ecological approaches to sexual selection: While many studies of sexual selection have focused on how the evolution of exaggerated traits is opposed by natural selection, fewer studies have examined how natural and sexual selection may act in parallel on traits. Much of my research focuses on quantifying both natural and sexual selection in natural populations. For example, I study performance traits in lizards that are important for survival, but are also important to males during territory acquisition (bite force) and territory maintenance (sprint speed). I have shown that bite force is important during fights and is a strong predictor of male reproductive success, whereas high sprint speed capacity allows more effective defense of territories and mates. Further, the sex differences in the intensity of selection that I found on these traits likely have contributed to the pronounced sexual dimorphism in head and limb shape. But, what causes the sex differences in selection to exist at all? Kris Lappin (Cal Poly Pomona) and I are investigating population-level variation in bite-force performance, head morphology, and variance in male reproductive success in collared lizards to get at this question. Interestingly, we have found that geographically-separated populations display very marked differences in their degree of sexual dimorphism in morphology and bite-force performance, with some populations displaying little dimorphism and aggression and others displaying strong dimorphism and high levels of aggression. The importance of biting ability in determining male mating success leads us to predict differing strengths of sexual selection on performance across the species' distribution. We are currently investigating this possibility, as well as how other selective forces are involved.
(2) Proximate determinants of performance: My work that addresses the adaptive significance of performance traits is complemented by studies of proximate mediators of those traits to better understand the "trickle-down" effects of selection on performance. I study the role of hormones and morphology in determining maximal performance to better understand how selection shapes those lower-level traits. My work with free-ranging green anole lizards showed that an age-related shift in testosterone levels in sexually mature males is associated with a large relative increase in head size and bite force. Experimental elevation of the hypothalamic trigger of testosterone (GnRH) in small and large males revealed that the difference in testosterone production among male size classes is due to physiological differences in response to hypothalamic hormones, not social suppression of testosterone production in small males. My work with Gallotia galloti revealed that increasing testosterone exogenously does not affect all muscles equally, which may explain the equivocal performance effects of testosterone on human athletic performance. At a broader scale I am investigating testosterone-performance-behavior relationships within the Caribbean Anolis lizard radiation to determine how repeated historical divergence in habitat use, mating systems, social behavior, and performance are tied together by hormonal mechanisms.
(3) Evolution of locomotor performance: It seems intuitive that locomotion is important to animals while escaping predators, foraging, and interacting with conspecifics, thus potentially impacting fitness. However, it remains largely unexplored whether organisms actually use maximal performance capacities in any of these contexts. I seek to determine what proportion of their maximal capacity individuals use in nature, whether this varies among demographic groups in a population, and what the fitness consequences are. My research on collared lizards showed that older individuals use relatively little of their maximal sprinting ability while escaping predators or foraging, whereas younger lizards use a high proportion. Accordingly, I detected selection for adults to be merely 'adequate' at escaping predators in nature, whereas I found strong directional selection for high maximal speed in hatchlings. These results offer a cautionary tale of viewing organismal performance in a simplistic manner and provide an ecological context into which we can place physiological measures of the phenotype that are normally measured in a laboratory.
(4) Gliding lizards as a model system in evolutionary ecology: I am examining how a gliding lifestyle, as well as sympatric assemblages of up to 7 species, has influenced the evolution of sexual dimorphism and body size and shape in Draco. I am conducting a phylogenetic comparison of functional morphology in this unique radiation of southeast Asian lizards with Jim McGuire at UC - Berkeley (Thanks to the Berkeley MVZ, the Field Museum, the California Academy of Sciences, and the Texas Natural History Collections for logistical and financial support!) Are Draco 'New World Anoles' as has been suggested? (Probably not, but why not?)
Sceloporus cyanostictus in the Sierra de San Lorenzo Mountains, Coahuila, Mexico
(35) Husak, J. F., and J.G. Swallow. 2011. Compensatory traits and the evolution of male ornaments. Behaviour, in press.
(34) 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. pdf
(33) 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. pdf
(32) 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. Journal of Experimental Zoology 313A:9-16. pdf (Highlighted in Outside JEB)
(31) Husak, J. F., D. J. Irschick, S. D. McCormick, and I. T. Moore. 2009. Hormonal regulation of whole-animal performance: implications for selection. Integrative and Comparative Biology 49:349-353. pdf
(30) Husak, J. F., and D. J. Irschick. 2009. Steroid use and human performance: lessons for integrative biologists. Integrative and Comparative Biology 49:354-364. pdf
(29) Huyghe, K., J. F. Husak, A. Herrel, Z. Tadić, 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. pdf
(28) 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. pdf (Recommended in Faculty of 1000 Biology)
(27) 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. pdf
(26) Husak, J. F., and I. T. Moore. 2008. Stress hormones and mate choice. Trends in Ecology and Evolution 23:532-534. pdf
(25) Husak, J. F., and S. F. Fox. 2008. Sexual selection on locomotor performance. Evolutionary Ecology Research 10:213-228. pdf
(24) 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. pdf
(23) 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. pdf
(22) 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. pdf
(21) Irschick, D. J., 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 pdf (Cover)
(20) 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 species of turtles. Environmental Toxicology and Chemistry 26:1733-1741. pdf
(19) Husak, J. F. 2006. Does survival depend on how fast you can run or how fast you do run? Functional Ecology 20:1080-1086. pdf (Erratum)
(18) Husak, J. F., M. B. Lovern, S. F. Fox, and R. A. Van Den Bussche. 2006. Faster lizards sire more offspring: sexual selection on whole-animal performance. Evolution 60:2122-2130. pdf (Highlighted in Outside JEB)
(17) Husak, J. F. 2006. Do female collared lizards change field use of maximal sprint speed capacity when gravid? Oecologia 150:339-343. pdf
(16) 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. pdf
(15) 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. pdf (Highlighted in Nature, Outside JEB, and ScienceShots)
(14) 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. pdf
(13) 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. pdf
(12) Husak, J. F. 2006. Does speed help you survive? A test with collared lizards of different ages. Functional Ecology 20:174-179. pdf
(11) 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. pdf
(10) 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. pdf
(9) 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. pdf
(8) 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. pdf
(7) Husak, J. F. 2004. Signal use by collared lizards, Crotaphytus collaris: the effects of familiarity and threat. Behavioral Ecology and Sociobiology 55:602-607. pdf
(6) 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. pdf
(5) Husak, J.F. and S.F. Fox. 2003. Adult male collared lizards (Crotaphytus collaris) increase aggression towards displaced neighbours. Animal Behaviour 65:391-396. pdf
(4) 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. pdf
(3) Husak, J. F., and E. N. Ackland. 2003. Foraging mode of the reticulate collared lizard, Crotaphytus reticulatus. Southwestern Naturalist 48:282-286. pdf
(2) Husak, M. S. and J. F. Husak. 2002. Low frequency of site fidelity by golden-fronted woodpeckers. Southwestern Naturalist 47:110-114.
(1) 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.
Great Field Sites!
Glass Mountains, Oklahoma
New Orleans swamp