Meeting Abstract
Many species of turtles and all marine turtles have environmentally determined sex. Temperature is considered to be the leading environmental factor directing embryos toward male or female phenotypes. This developmental process has lead many authors to conclude that marine turtles may be particularly extinction-prone because elevated environmental temperatures (a product of global warming) will skew sex ratios to extreme and unsustainable levels. We review these and other assumptions and discuss field and laboratory evidence suggesting that sea turtles are more resilient to climate change than previously thought. We sampled primary sex ratios from in situ sea turtle nests at a major Florida rookery under typical and more extreme climatic conditions over 10 nesting seasons to examine predicted effects of increasing temperature on nest sex ratios. Sex was verified using gonad and gonadal duct morphology. Hatchling samples from in situ nests were 100% female when weather conditions were hotter and drier than normal. Eggs that incubated in hot but wet years produced mixed sex samples, including samples that were strongly male- or strongly female-biased. Experimental clutches reared under moist laboratory conditions at temperatures predicted to produce female-biased sex ratios instead produced ~ 90% males. Together these results suggest a potential source of resiliency due to an unappreciated variable (moisture) that modified the response to temperature. These findings cause us to question the generally accepted assumption that changes in temperature, alone, will have a negative impact on sex ratios.
