99 Percent of Turtles are Becoming Female Thanks to Global Warming

Khryss | Published 2018-01-17 06:06

Why is that a bad thing? Read further.

Sex in reptiles are actually determined by the temperature at which the eggs are incubated and not by chromosomes like humans. For sea turtles, this is known as temperature-dependent sex determination (TSD). That is, their eggs has to hatch at a certain temperature over incubation period (i.e. averaged 29ºC or 84ºF) in order to have a 50-50 mix of male and female offspring. Moreover, when the temperature is warmer, the hatch tend to have more females and vice versa.

It was in 2014 that they realized the Earth is getting so warm that most newly hatched loggerhead turtles were female. However, enough males are still present, ensuring a future for the population. But not anymore...

Now, Dr Michael Jensen of the National Oceanic and Atmospheric Administration a more serious threat for the endangered green sea turtles (Chelonia mydas) at the northern end of the Great Barrier Reef. While the southern end had 65-69 percent female turtles, the mid-reef region has almost no hatcheries. And at the north of Cooktown, 99.1 percent of juvenile turtles were female, along with 86.8 female adults!

That means an essential part for this species' survival is missing: males.

 “The northern GBR rookeries have been producing primarily females for more than two decades, and the complete feminization of this population is possible in the near future,” Jensen and co-authors wrote in Current Biology.

Moreover, TSD species are known to survive certain hotter and colder world temperature before thanks to evolution. As to the green turtles, they may move to nesting at different times to ensure a better sex ratio. But while this may sound like a good news, these actually don't happen very quickly and it may be too before they develop such mechanisms.

Local extinction of this species is not a far behind possibility and it is once again humanity's fault.


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