Unlike humans, sea turtles and other reptiles like crocodiles do not have sex chromosomes. Their sex is defined during development by the incubation environment. In sea turtles, sex is determined by the nest’s temperature: warmer temperatures produce females and cooler temperatures produce males. It is especially challenging to identify the sex of hatchling sea turtles because they lack external sexual organs and heteromorphic sex chromosomes –– no X or Y. To date, there are a limited number of ways to reliably identify sex in turtle hatchlings. With the rapid increase of global temperatures, there is an urgent need to clearly assess sex ratios in these imperiled animals.
Researchers from Florida Atlantic University’s Charles E. Schmidt College of Science have developed a first-of-its-kind technique that is minimally invasive and greatly enhances the ability to measure neonate turtle sex ratios at population levels across nesting sites worldwide. They used this technique to identify sex in neonates of two turtle species: a freshwater turtle (Trachemys scripta) and a marine turtle (Caretta caretta) using analysis of small blood samples. This is the first time that differences in sex-specific protein expression patterns have been identified in blood samples of hatchlings with temperature-dependent sex determination. This research is a crucial step in assessing the impact of climate change on imperiled turtle species.
For the study, published in Scientific Reports , researchers used an immunoassay approach to test samples for the presence of several proteins known to play an important role in sex differentiation. Results of the study showed that anti-müllerian hormone (AMH) can reliably be detected in blood samples from neonate male turtles but not females and can be used as a sex-specific marker.
Read more at Florida Atlantic University
Photo: Marine scientists at FAU's Charles E. Schmidt College of Science release a baby loggerhead sea turtle. (Photo credit: Dane Ralph)