Speaker 1: Welcome to brain Stuff, a production of I Heart Radio
Speaker 1: Pay brain Stuff. I'm Lauren volk Baum and this is
Speaker 1: a classic episode from our former host, Christian Sagar. We
Speaker 1: usually think of evolution as being a near cosmically slow process,
Speaker 1: and often it is. After all, living beings in our
Speaker 1: relationships with our environments can be really complex, with dozens
Speaker 1: of genes coming together to create the traits that help
Speaker 1: or hurt our chances of survival. But you don't have
Speaker 1: to be a germ, or a fruit fly or a
Speaker 1: peace shoot to show change quickly. Today's episode is the
Speaker 1: strange story of a particularly swift lizard evolution. Hey, brain Stuff,
Speaker 1: it's Christian Sager here. So evolution takes time, but just
Speaker 1: how much time it takes is the issue. How long,
Speaker 1: for instance, did it take therapod dinosaurs to evolve into
Speaker 1: modern birds tens, if not hundreds of millions of years.
Speaker 1: But since the turn of the last century, when American
Speaker 1: biologist Herman Bumpust noticed that individual sparrows in a population
Speaker 1: became larger as the result of one huge snowstorm, scientists
Speaker 1: have been observing instances of short bursts of evolutionary progress
Speaker 1: over a significantly brief period of time. Definitive instances of
Speaker 1: rapid evolution are tough to come by, though, even in
Speaker 1: these days of advanced genetic testing, but a recent study
Speaker 1: published in the journal Science finds that over the course
Speaker 1: of just a few months, green annully lizards living in
Speaker 1: the area of the Mexico Texas border evolved a rapid
Speaker 1: genetic tolerance to cold weather after an unusually frigid winter.
Speaker 1: Green Annullies are warm weather reptiles that evolved on the
Speaker 1: Caribbean island of Cuba. They found their way to the
Speaker 1: mainland long ago, but a prolonged and extreme cold snap
Speaker 1: can really put the hurt on a population of annuls.
Speaker 1: The winter of did just that before that year's famed
Speaker 1: polar vortex hit. However, the research team collected annulis in
Speaker 1: August to find out just how cold one of these
Speaker 1: lizards could get before its motor function was compromised, specifically,
Speaker 1: that is, when it couldn't right itself when it was
Speaker 1: knocked over. They collected annuals from five different sites across
Speaker 1: Texas and found that when gradually cooled in a chamber
Speaker 1: in the lab, the individuals from the southernmost site became
Speaker 1: uncoordinated at around fifty two degrees fahrenheit or eleven degrees celsius,
Speaker 1: but the ones collected from the northernmost site became unable
Speaker 1: to right themselves at around forty three degrees fahrenheit or
Speaker 1: six degrees celsius. Because the scientists already had genetic samples
Speaker 1: from the lizards in the first study, When a few
Speaker 1: months later temperatures plummeted to lows that hadn't been seen
Speaker 1: in fifteen years, the researchers went out and collected some
Speaker 1: of the surviving lizards from all five sites. They placed
Speaker 1: them in the same cooling chambers and found the southernmost
Speaker 1: Annullies exhibited much more cold resistance than the ones that
Speaker 1: had been collected back in the summer. They could now
Speaker 1: stand strong in the face of forty three degrees fahrenheit
Speaker 1: or six degrees celsius. RNA sequencing before and after the
Speaker 1: cold front also revealed significant differences between individuals from the
Speaker 1: southern genomic regions before and after the weather event. By
Speaker 1: the way, did you know that Annulli's living in urban
Speaker 1: areas have stickier feet than their country cousins. Apparently it's
Speaker 1: an evolutionary adaptation to having to cling to class and metal.
Speaker 1: Now I want to be bitten by a radioactive annually
Speaker 1: so I can crawl waltz with them. Today's episode was
Speaker 1: written by Jesselyn Shields and produced by Dylan Fagan, Little Berlante,
Speaker 1: and Tyler Clang. For more on lit and lots of
Speaker 1: other topics, visit how stuff works dot com. Brain Stuff
Speaker 1: is a production of I Heart Radio. For more podcasts
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Speaker 1: or wherever you listen to your favorite shows.