The Janzen Lab of Ecological and Evolutionary (mostly) Herpetology
We are a research facility at Iowa State University run by Dr. Fredric Janzen, a professor in the Department of Ecology, Evolution, and Organismal Biology.
Our research interests involve the study of ecology and evolution, including mechanistic work at the molecular and organismal levels, field studies that document the importance of phenotypic variation, and a comparative view of the long-term consequences of this variation. To do so, we often integrate molecular and quantitative genetic techniques with experimental laboratory and field studies, largely focusing on the impact of environmental and genetic factors in mediating the expression of physiological, behavioral, and life-history traits. Using these conceptual approaches in concert with comparative techniques enables us to assess important biological issues, including
- the biological significance of diverse sex-determining mechanisms,
- the impacts of environmental and genetic factors on variation in early life-history traits, and
- the current and historical genetic and demographic structure of populations, with an emphasis on elucidating adaptive processes and solving conservation concerns.
Our focal study organisms are usually reptiles, especially turtles, because they exhibit tremendous diversity in sex-determining mechanisms (including temperature-dependent sex determination) and in their life histories, rendering them excellent subjects for our topics of research interest. A number of students work under Dr. Janzen's direction on projects, such as
- molecular phylogenetics, phylogeography, and conservation genetics of reptiles, including Apalone, Graptemys, Heterodon, and Emydoidea,
- molecular ecology of mating systems in natural populations of turtles,
- population dynamic responses of turtles (e.g., Chrysemys) to exploitation by humans,
- experimental field studies of environmental causes of susceptibility to predation of neonatal reptiles (e.g., Trachemys),
- experimental evolution of sex ratio and sex-determining mechanisms in the nematode C. elegans, and (of course)
- ecology and evolution of sex ratio and sex-determining mechanisms in natural populations of turtles, including assessments of inheritance of these traits in nature and their sensitivity to climate change and human habitat modification.
These are the primary research areas on which the Janzen Lab concentrates. For more information, please contact Dr. Janzen.
- Evolutionary ecology of sex-determining mechanisms in reptiles
- Experimental evolution of sex ratio and sex-determining mechanisms in C. elegans
- Life-history evolution and functional ecology of reptiles
- Phylogenetics, molecular ecology, and phylogeography of North American reptiles
- Anthropogenic influences on turtle populations
- Radchuk, V. et al. 2018. Animals respond to climate change by adaptive shifts in phenological traits. Nature Communications, in press.
- Edge, C. et al. 2017. Phenotypic plasticity of nest timing in a post-glacial landscape: how do reptiles adapt to seasonal time constraints? Ecology 98:512-524.
- Refsnider, J. M., and F. J. Janzen. 2016. Temperature-dependent sex determination under rapid anthropogenic environmental change: evolution at a turtle's pace? Journal of Heredity 107:61-70.
- Schwanz, L. E. et al. 2016. Sex-specific survival to maturity and the evolution of environmental sex determination. Evolution 70:329-341.
- Warner, D. A. et al. 2016. Decades of field data reveal that turtles senesce in the wild. Proceedings of the National Academy of Sciences USA 112:7055-7060.
- McGaugh, S. E. et al. 2015. Rapid molecular evolution across amniotes of the IIS/TOR network. Proceedings of the National Academy of Sciences USA 112:7055-7060.