sea turtles

sex ratios

incubation temperature

Current Biology

•We developed a novel method to estimate primary sex ratios in sea turtles•We found extremely female-biased sex ratios in an important sea turtle population Climate change affects species and ecosystems around the globe [1Root T.L. Price J.T. Hall K.R. Schneider S.H. Rosenzweig C. Pounds J.A. Fingerprints of global warming on wild animals and plants.Nature. 2003; 421: 57-60Crossref PubMed Scopus (3505) Google Scholar]. The impacts of rising temperature are particularly pertinent in species with temperature-dependent sex determination (TSD), where the sex of an individual is determined by incubation temperature during embryonic development [2Janzen F.J. Climate change and temperature-dependent sex determination in reptiles.Proc. Natl. Acad. Sci. USA. 1994; 91: 7487-7490Crossref PubMed Scopus (380) Google Scholar]. In sea turtles, the proportion of female hatchlings increases with the incubation temperature. With average global temperature predicted to increase 2.6°C by 2100 [3Intergovernmental Panel on Climate ChangeClimate Change 2014: Synthesis Report, Core Writing Team.in: Pachauri R.K. Meyer L. Intergovernmental Panel on Climate Change, Geneva2014Crossref Google Scholar], many sea turtle populations are in danger of high egg mortality and female-only offspring production. Unfortunately, determining the sex ratios of hatchlings at nesting beaches carries both logistical and ethical complications. However, sex ratio data obtained at foraging grounds provides information on the amalgamation of immature and adult turtles hatched from different nesting beaches over many years. Here, for the first time, we use genetic markers and a mixed-stock analysis (MSA), combined with sex determination through laparoscopy and endocrinology, to link male and female green turtles foraging in the Great Barrier Reef (GBR) to the nesting beach from which they hatched. Our results show a moderate female sex bias (65%–69% female) in turtles originating from the cooler southern GBR nesting beaches, while turtles originating from warmer...

Environmental Warming and Feminization of One of the Largest Sea Turtle Populations in the World