WEBVTT - Swift Lizard Evolution

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<v Speaker 1>Welcome to brain stuff from how stuff works. Hey, brain stuff,

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<v Speaker 1>it's Christian Sager here. So evolution takes time, but just

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<v Speaker 1>how much time it takes is the issue. How long,

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<v Speaker 1>for instance, did it take therapod dinosaurs to evolve into

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<v Speaker 1>modern birds tens, if not hundreds, of millions of years.

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<v Speaker 1>But since the turn of the last century, when American

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<v Speaker 1>biologist Herman Bumpust noticed that individual sparrows in a population

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<v Speaker 1>became larger as the result of one huge snowstorm, scientists

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<v Speaker 1>have been observing instances of short bursts of evolutionary progress

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<v Speaker 1>over a significantly brief period of time. Definitive instances of

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<v Speaker 1>rapid evolution are tough to come by, though, even in

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<v Speaker 1>these days of advanced genetic testing, but a recent study

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<v Speaker 1>published in the journal Science finds that over the course

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<v Speaker 1>of just a few months, green annully lizards living in

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<v Speaker 1>the area of the Mexico Texas border evolved a rapid

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<v Speaker 1>genetic tolerance to cold weather after an unusually frigid winter.

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<v Speaker 1>Green Annullies are warm weather reptiles that evolved on the

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<v Speaker 1>Caribbean island of Cuba. They found their way to the

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<v Speaker 1>mainland long ago, but a prolonged and extreme cold snap

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<v Speaker 1>can really put the hurt on a population of annuls

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<v Speaker 1>The winter of did just that before that year's famed

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<v Speaker 1>polar vortex hit. However, the research team collected annulis in

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<v Speaker 1>August to find out just how cold one of these

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<v Speaker 1>lizards could get before its motor function was compromised, specifically,

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<v Speaker 1>that is, when it couldn't right itself when it was

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<v Speaker 1>knocked over. They collected annuals from five different sites across

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<v Speaker 1>Texas and found that when gradually cooled in a chamber

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<v Speaker 1>in the lab, the individuals from the southernmost site became

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<v Speaker 1>uncoordinated at around fifty two degrees fahrenheit or eleven degrees celsius,

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<v Speaker 1>but the ones collected from the northernmost site became unable

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<v Speaker 1>to right themselves at around forty three degrees fahrenheit or

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<v Speaker 1>six degrees celsius. Because the scientists already had genetic samples

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<v Speaker 1>from the lizards in the first study, when a few

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<v Speaker 1>months later temperatures plummeted to lows that hadn't been seen

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<v Speaker 1>in fifteen years, the researchers went out and collected some

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<v Speaker 1>of the surviving lizards from all five sites. They placed

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<v Speaker 1>them in the same cooling chambers and found the southernmost

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<v Speaker 1>Annullies exhibited much more cold resistance than the ones that

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<v Speaker 1>had been collected back in the summer. They could now

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<v Speaker 1>stand strong in the face of forty three degrees fahrenheit

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<v Speaker 1>or six degrees celsius. RNA sequencing before and after the

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<v Speaker 1>cold front also revealed six significant differences between individuals from

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<v Speaker 1>the southern genomic regions before and after the weather event.

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<v Speaker 1>By the way, did you know that Annulli's living in

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<v Speaker 1>urban areas have stickier feet than their country cousins. Apparently

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<v Speaker 1>it's an evolutionary adaptation to having to cling to class

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<v Speaker 1>and metal. Now I want to be bitten by a

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<v Speaker 1>radioactive Annulli so I can crawl walls with him. Today's

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<v Speaker 1>episode was written by jess Lynn Shields and produced by

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<v Speaker 1>Dylan Fagan. For more on this and other topics, please

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<v Speaker 1>visit us at how stuff works dot com.