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Graduate student’s research: Turtles, sex determination, and climate change

turtle hatchling

Turtle hatchling.

Illinois State Ph.D. student Amanda Wilson Carter has explored the marshes of Illinois and the swamps of South Carolina in pursuit of slider turtles for her research this summer.

Many turtles, including the species she studies, Trachemys scripta, undergo sex determination in an unusual way. The sex of hatchling turtles is determined by the incubation temperature of the eggs (i.e. temperature-dependent sex determination, TSD), such that warm temperatures produce all females and cool temperatures produce all males.

However, eggs also contain varying levels of maternally-derived estrogens, where eggs laid later in the nesting season have higher levels of estrogens than eggs laid earlier in the nesting season. Under artificial conditions, estrogens can override temperature effects to feminize hatchlings.

Carter’s research seeks to understand if natural seasonal variation in estrogen levels can affect hatchling sex determination. Understanding how estrogens interact with temperature to affect sex determination will enhance our understanding of TSD, and increase our ability to predict how reptiles with TSD may respond to climate change.