Ask Fuzzy: What determines a turtle's sex?

Among these idiosyncrasies is something fundamental to the survival of any species - whether the sex of offspring is male or female.

For humans and other placental mammals, sex is determined when the egg is fertilised by the sperm. But, like alligators and crocodiles, turtles have "temperature-dependent sex determination".

As that suggests, the environment is more important than the chromosomal arrangement in determining sex.

After the eggs have been laid, if they are incubated at temperatures below 27.7 degrees Celsius, hatchlings will be male. If the temperature is about 31 degrees, the hatchlings will be female.

At a temperatures between 27.7 and 31 degrees, the nest will give rise to a mix of female and male hatchlings.

This occurs due to regulation of important pathways during embryonic development.

While this is an incredibly interesting way for species to evolve, this mechanism may be detrimental to turtles. With the rise of average temperatures caused by climate change, more hatchlings are being born female.

A recent study of green sea turtles in the Great Barrier Reef demonstrated that 99 per cent of turtles born were female. This has the potential to be catastrophic for the survival of this species and is a real threat to all other turtles.

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Without males for reproduction, the already endangered green sea turtle could become extinct.

In light of this, the World Wildlife Fund is funding a research project in the Great Barrier Reef.

This includes shading the reefs with native trees or manmade infrastructure, and irrigating the reef with seawater and rainwater.

These all aim to cool the beach shores to a temperature where the development of male hatchlings is possible.

These studies have demonstrated an average decrease in temperature of 1.3 degrees.

While this is by no means a "fix", 1.3 degrees could be a lifeline to turtles on a warming planet.

Listen to the Fuzzy Logic Science Show at 11am every Sunday on 2XX 98.3FM.

Send your questions to AskFuzzy@Zoho.com Twitter@FuzzyLogicSci

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