SICB 2018: Heat Stress and Deformed Faces

Incubation temperature is an important factor in development for anoles (and other ectotherms). Thom Sanger, a professor at Loyola University in Chicago, IL, presented his research on how high temperatures affect brain formation in developing anole embyros. With the help of undergraduates and a high school summer intern, Dr. Sanger found that when developing eggs were heat-shocked, many embryos were lost (75%), but for those that survived, forebrains became smaller (In the figure, A is normal and B is deformed). Interestingly, malformation of the forebrain affects the size and shape of the face, and so surviving heat-shocked embryos exhibit cranial malformations. As Sanger continues his research, he will follow a neural degeneration hypothesis, which boils down to (no pun intended) the idea that thermal stress increases the rate of cell death, and the amount of cell death affects facial shape. While the effects of high temperature may seem alarming, Sanger notes that this does not happen very often in nature; females are generally pretty good at selecting suitable nest sites. But, because development is similar across reptile taxa, anoles can be an excellent model system to inform predictions about what may happen to species that are in danger.