Environmental Variation and Scale-Size Evolution
Many broadly distributed taxa are subject to a wide array of environmental conditions across their range. I co-led a comparative study examining Bergmann’s clines and variation in dorsal scale row number (used as a proxy for scale size) in 106 species and populations of the Central and North American lizard genus, Sceloporus. Lizards (Sceloporus in particular) have been the subjects of several recent publications highlighting the impacts of global climate change (e.g. Sinervo et al. 2010, Science). In our study, we tested a number of adaptive hypotheses relating scale and body size to several environmental variables. Our
data show that larger bodied Sceloporus are found in arid areas with high maximum temperatures, confirming the predicted trend for many squamates that larger species tend to exist at lower latitudes and warmer temperatures, the opposite of Bergmann’s Rule. In addition, we found that scale size decreases with latitude—areas that are more arid, with higher maximum and lower minimum temperatures and have lower total annual precipitation. This result is contrary to the hypothesis that lizards from warmer environments will exhibit fewer and thus larger scales. Instead, it appears that desert-like selective regimes lead to Sceloporus with smaller scales.
Much of my current work on Greater Antillean Anolis lizards focuses on similar, environmentally-based patterns of morphological variation.
Related Publications (click for PDF)
Oufiero, C.E.†, Gartner, G.E.A.†, Adolph, S.C., and Garland Jr., T. 2011. Latitudinal and climatic variation in body size and dorsal scale counts in Sceloporus lizards: a phylogenetic perspective. Evolution. 65:3590-3607
(† Co First Authorship; see cover photo at left)