You are here: Home People Tracy Langkilde
Tracy Langkilde

Tracy Langkilde

Main Content

Professor and Head of Biology

208 Mueller
University Park, Pennsylvania 16802

Graduate Programs

Biology (BIOL)

Ecology (ECLGY)


  1. Ph.D., University of Sydney, Australia, 2005
  2. B.S., James Cook University, Australia, 1999

Postdoc Training

  1. Gaylord Donnelley Environmental Fellow, Yale University, 2005 - 2007

Honors and Awards

  1. George Mercer Award, Ecological Society of America, 2011

Research Interests

My lab works at the interface of ecology and evolution to understand how an organism's traits are matched to its environment and responds to novel selective pressures imposed by global environmental change, and the consequences of this adaptation. Our research takes an integrative approach, applying behavioral observations, endocrine assays, morphological analysis tools, and molecular approaches to both field and laboratory studies, with a focus on reptiles and amphibians. This work has both basic and applied importance, informing the role of evolutionary processes in assembly and dynamics of natural communities, and our understanding of the resilience and responses of native populations to rapid perturbations caused by global environmental change. 

See more at

Selected Publications

See a full list at

Mina O., Gall H.E., Elliott H.A., Watson J.E., Mashtare M.L., Langkilde T., Harper J.P., and Boyer E.W. 2018. Estrogen occurrence and persistence in vernal pools impacted by wastewater irrigation practices. Agriculture, Ecosystems and Environment 257: 103-112.

Owen D.A.S., Robbins T.R. and Langkilde T. 2018. Trans-generational but not early-life exposure to stressors influences offspring morphology and survival. Oecologia 186: 347-355

Tylan C. and Langkilde T. 2017. Local and systemic immune responses to different types of phytohemagglutinin in the green anole: Lessons for field ecoimmunologists.  Journal of Experimental Zoology A 327: 322-332.

Carlson, B.E. and Langkilde T. 2017. Body size variation in aquatic consumers causes pervasive community effects, independent of mean body size. Ecology and Evolution 7: 9978-9990.

Langkilde T., Thawley C.J. and Robbins T.R. 2017. Behavioral Adaptations to Invasive Species: Benefits, Costs, and Mechanisms of Change. In M. Naguib, J. Podos, L. W. Simmons, L. Barrett, S. Healy, & M. Zuk (Eds.), Advances in the Study of Behavior (pp. 199–235).

Kelehear C., Graham S.P. and Langkilde T. 2017. Defensive strategies of Puerto Rican Dwarf Geckos (Sphaerodactylus macrolepis) against Invasive Fire Ants. Herpetologica 73: 48-54

McCormick G.L., Robbins T.R., Cavigelli S.A. and Langkilde T. 2017. Ancestry trumps experience: Transgenerational but not early life stress affects the adult physiological stress response. Hormones and Behavior 87: 115-121 

Herr M.W., Graham S.P. and Langkilde T. 2017. Stressed snakes strike first: Hormone levels and defensive behavior in free ranging Cottonmouths (Agkistrodon piscivorus). General and Comparative Endocrinology 243: 89-95

Thawley, C.J. and T. Langkilde. 2017. Attracting unwanted attention: generalization of behavioural adaptation to an invasive predator carries costs. Animal Behaviour 123: 285-291

Schrey A.W., Robbins T.R., Lee J., Dukes D. W. Jr., Ragsdale A.K., Thawley C. and Langkilde T. 2016. Epigenetic response to environmental change: DNA methylation varies with invasion status. Environmental Epigenetics 2016 2: dvw008

Tennessen J.B., Parks S.E., Tennessen T.P. and Langkilde T. 2016. Raising a racket: invasive species compete acoustically with native tree frogs. Animal Behavior 114: 53-61

McCormick G.L., Shea K. and Langkilde T. 2015. How do duration, frequency, and intensity of exogenous CORT elevation affect immune outcomes of stress? General and Comparative Endocrinology 222: 81-87

Swierk L.N., Graham S.P. and Langkilde T. 2014. The stress of scramble: Sex differences in behavior and physiological stress response in a time-constrained mating system. Behavioral Ecology and Sociobiology 68: 1761-1768.

Tennessen J.B., Parks S. P. and T. Langkilde. 2014. Traffic noise causes physiological stress and impairs breeding migration behavior in frogs. Conservation Physiology 2 doi: 10.1093/conphys/cou032

Zuk M., Bastiaans E., Langkilde T. and E. Swanger. 2014. The role of behavior in the establishment of novel traits. Animal Behavior 92: 333-344.

Swierk L.N. and T. Langkilde. 2013. Bearded ladies: Females suffer fitness consequences when bearing male traits. Biology Letters 9: 20130644.

Robbins T.R. and T. Langkilde. 2012. The consequences of lifetime and evolutionary exposure to toxic prey: Changes in avoidance behavior through ontogeny. Journal of Evolutionary Biology 25: 1937-1946.

Trompeter W. P. and T. Langkilde. 2011. Invader danger: lizards faced with novel predators exhibit an altered behavioral response to stress. Hormones and Behavior 60: 152-158.

Langkilde T. 2009. Invasive fire ants alter behavior and morphology of native lizards. Ecology 90: 208-217.