Climate Change to Eliminate Men? More Female Sea Turtles Born as Climate Warms

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A new study in the science journal Nature Climate Change has found the warmer climate poses a threat to the sea turtle population. The warming world poses challenges for species, like the sea turtles, whose sex determination is temperature-dependent where warmer incubation temperatures lead to production of more female hatchlings.

With climate change, the sands where sea turtles incubate rises in temperature and results into an entirely female population, which in turn may risk the reptile's extinction.

The study noted the hotter climate can provide short-term benefits as the warming climate triggers a larger share of female hatchlings but may raise the natural population growth. But if such trend continues, males could die-off and trigger the extinction of the species.

"Sea turtles are unusual in that the gender of the offspring is not driven by sex chromosomes, as in humans," Prof. Graeme Hays, one of the study's lead authors, told The Guardian.

Unlike humans, reptile reproduction is extremely sensitive to temperature. The temperature of the sand where female turtles bury their eggs determines the offspring's sex.

According to the Sydney Morning Herald, "The pivotal temperature is an oddly uniform 29 degrees for incubation, beyond which more females emerge from the eggs. At about 30.5 degrees, populations become fully female."

The study looked at the Cape Verde Island turtles in the Atlantic Ocean and found light-colored beaches currently produce 70.10 percent females whereas dark-colored beaches produce 93.46 percent females.

"Rising sea levels resulting in the loss of nesting beaches (through erosion) could push local turtle populations over the brink unless new suitable nesting beaches are found," Hays said.

A similar trend has already been identified in the Caribbean's green turtles. It's possible that the same challenge could arise for other reptiles like crocodiles, lizards and alligators whose sex are also dependent on temperature.

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