Field and laboratory studies of plasticity in performance and morphology

Functional morphologists often assume invariance in morphological and biomechanical traits. However, our research has been examining how key sexual traits (e.g., the anole dewlap, pictured above), biomechanical traits (bite force), and morphology (head size and shape) change seasonally in lizards in different environments. Our research reveals a complex pattern of non-linear seasonal change in all of these parameters, suggesting that performance is not static, but rather than individual animals can easily change over short periods of time. For example, average bite force in an individual lizard can change by as much as 30%, and dewlap area change change by up to 50%, within a year, even as growth is minimal. This work also has profound implications for behavioral ecology because it shows that sexual traits, such as the anole dewlap are also not static, implying that the social status of individuals changes seasonally as well. We are currently expanding this arena of research to include studies of genetic paternity and hormones to understand the ecological and behavioral consequences of such palsticity.

Relevant literature:

Irschick DJ, Ramos M, Buckley C Elstrott J, Carlisle E, Lailvaux S, Bloch N, Herrel A, VanHooydonck B.  2006.  Are morphology->performance relationships invariant across different seasons?  A test with the green anole lizard (Anolis carolinensis).  Oikos. 114:49-59.

Irschick DJ, Meyers JJ.  2006.  An analysis of the relative roles of plasticity and natural selection on morphology and performance in a lizard (Urosaurus ornatus).  Oecologia.  153:489-499.