WEBVTT - BrainStuff Classics: Why Are Some Sea Turtles Hatching Almost All Female?

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<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hey

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<v Speaker 1>brain Stuff, I'm more in vogel Bomb and this episode

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<v Speaker 1>is a classic from our archives. Over the past few years,

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<v Speaker 1>we've all seen changes to expected weather patterns. There have

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<v Speaker 1>been more hurricanes in some areas, more droughts, and others

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<v Speaker 1>warmer winters. Here in Atlanta, where we produce this show,

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<v Speaker 1>some of these effects of climate change are pretty obvious,

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<v Speaker 1>but this episode is about one that's more subtle, if

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<v Speaker 1>just as big, the difference in how some sea turtles

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<v Speaker 1>are being born. Hey brain stuffling vocal bomb here. Australia's

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<v Speaker 1>Great Barrier Reef is an enormous climate change experiment that's

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<v Speaker 1>not happening in the safe isolation of a laboratory. Instead,

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<v Speaker 1>the warming waters off the east coast of the continent

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<v Speaker 1>have a profound real world effect on thousands of miles

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<v Speaker 1>of coral as well as the animals that live there.

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<v Speaker 1>For decades, scientists have suspected that increases in ocean's temperatures

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<v Speaker 1>would affect sex ratios in certain animals, and rese it

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<v Speaker 1>shows that's exactly what's happening to the Pacific Green sea turtles.

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<v Speaker 1>In most of Earth's creatures, gender is determined during the

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<v Speaker 1>fertilization process. That's not true of animals like turtles, crocodiles,

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<v Speaker 1>and alligators, though, which rely on a concept called temperature

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<v Speaker 1>dependent sex determination, or TDS to dictate the sex of

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<v Speaker 1>their offspring. In the case of turtles, warming waters and

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<v Speaker 1>sands are altering the TDS process During the breeding season.

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<v Speaker 1>The turtles, which can grow to nearly five hundred pounds

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<v Speaker 1>that's about two kims, with a shell diameter of four

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<v Speaker 1>feet or one point two meters, flop ashore and bury

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<v Speaker 1>their eggs in the sand. The temperature of that sand

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<v Speaker 1>determines whether baby turtles will wind up with blue or

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<v Speaker 1>pink flippers. Figuratively speaking, if the incubation temperature is below

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<v Speaker 1>eighty two degrees fahrenheit or thirty degrees celsius, the turtles

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<v Speaker 1>will hatch as males. Above eighty eight degrees fahrenheit or

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<v Speaker 1>thirty one degree celsius, the babies will be female. A

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<v Speaker 1>similar problem has been reported in loggerhead turtles on Florida beaches,

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<v Speaker 1>since scientists have noticed a strong bias toward female turtles

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<v Speaker 1>in some instances. Up to to see how varying temperatures

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<v Speaker 1>might affect turtle populations. Scientists compared sex ratios of turtles

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<v Speaker 1>near multiple breeding grounds around the Great Barrier Reef. They

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<v Speaker 1>used blood tests and laparro scopy to determine the sex

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<v Speaker 1>of these animals. At the southern edge of the reef,

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<v Speaker 1>near Brisbane, water temperatures are cooler and female turtles outnumber

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<v Speaker 1>males by a ratio of two to one, about sixty

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<v Speaker 1>five to sixty nine percent female. However, about one thousand,

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<v Speaker 1>two hundred miles north, in the largest and most critical

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<v Speaker 1>sea turtle rookery in the Pacific Ocean, warmer sea and

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<v Speaker 1>air temperatures are having a dramatic effect of hatchlings are female.

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<v Speaker 1>Although each male can mate with more than one female

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<v Speaker 1>during a breeding season, a severe imbalance in sex ratios

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<v Speaker 1>doesn't bode well for temperature sensitive species like sea turtles. Furthermore,

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<v Speaker 1>once the incubating sand becomes too warm, it outright kills

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<v Speaker 1>the developing organism, further threatening turtle populations. The study was

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<v Speaker 1>published in January eighteen in the journal Cell Biology. The

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<v Speaker 1>researchers write, our study highlights the need for immediate management

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<v Speaker 1>strategies aimed at lowering incubation temperatures at key rookeries to

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<v Speaker 1>boost the ability of local turtle populations to adapt to

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<v Speaker 1>the changing environment and avoid a population collapse or even extinction.

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<v Speaker 1>Today's episode was originally produced by Tristan McNeil and is

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<v Speaker 1>based on the article of Great Barrier Reef Green sea

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<v Speaker 1>turtles are hatching female on how stuff works dot Com,

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<v Speaker 1>written by Nathan Chandler. Brain Stuff is production of I

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<v Speaker 1>Heart Radio in partnership with how stuff works dot Com

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<v Speaker 1>and is produced by Tyler Clang. Four more podcasts my

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