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Fifteen year ago , a cold-blooded snap freeze much of Florida ’s wildlife to death — including many of the state ’s invasive Burmese pythons ( Python bivittatus ) . But in this excerpt from " Slither : How Nature ’s Most Maligned Creatures Illuminate Our worldly concern " ( Gand Central Publishing , 2025 ) , skill writer Stephen Hall reveals that a subset of these Python were genetically predisposed to survive the common cold , setting the stage for speedy evolution that could help the invasive Snake disseminate further into North America .
In early January 2010 , a historic and prolonged cryptic freeze sweep across the southeasterly United States , reaching all the way into the subtropical Everglades . Temperatures brood around 50 degrees Fahrenheit ( 10 degrees Celsius ) for 48 hours ; on Jan. 11 , thermometers in South Florida dipped as low as 24.8 F ( minus 4 C ) . Most the great unwashed remember it , if at all , for the wintry Iguana iguana thatdropped out of treesand photos ofcitrus tree incase in icicles , like some fugitive Minnesota wintertime carnival smuggle into the Deep South .
Only a subset of Florida’s Burmese python population survived a cold snap in January 2010.
But to wildlife and trespassing specie expert , the Big Freeze marked the start of the bragging Unplanned Experiment .
The prompt impact on the Burmese python population was clear . carcass of idle snakes cluttered roads ; frozen specimen turned up in underground burrows ; farther northward in South Carolina , in the notorious " Where ’s Waldo " python enclosure , all 10 ophidian perished during the regional cold-blooded snap .
Researchersattributedthe mass dice - off to " maladaptive behavior , " meaning many serpent tried to enjoy above footing in the sun despite the frigid temperature , rather than seeking thermic shelter in hugger-mugger or aquatic burrows . Python " removals " — captures by hunting watch , which served as a rough indication of the general population — had peak in 2009 in the home park but plummeted almost five - fold in the following two or three years . It all looked like dear intelligence , at first .
Temperatures during the 2010 cold snap dropped so low, cold-blooded animals like iguanas were immobilized and lost their grip while perching on trees.
But universe numbers were still lacking , and " theoretical account " are still just models . Genesare where the synthetic rubber of biota take on the road of environmental challenge , and this is when the geneticists enter the write up . They were less interested in the many Snake that had die , and more concerned in the few that had survived .
Like all Hydra , Burmese pythons are ectotherms — they trust on lovingness from the environs because they do not generate their own metabolic heat — so they have to develop biological trick in their behavior or in their physiological resiliency in the face of life - menace frigidity to survive freeze event that do not occur in their native range . As the United States Geological Survey ( USGS ) overview put it , " some fate of the southerly Florida population come through " the 2010 upshot , " and these snake and their offspring make up the current universe . "
By 2014 , the bit of python removals in Everglades National Park had returned to pre - freeze levels . In genetic parlance , the 2010 freeze was a " chokepoint event " — only a few squeezed through and live on . But the ace that did , in the scriptural signified , went away and multiply .
Burmese pythons bask in the sun to stay warm, but this behavior proved fatal for many snakes during the 2010 cold snap.
set out around the class 2015 , several researchers studying python genomes to understand their metabolism became rum about the after effect of the big frost . Daren CardandTodd Castoeof the University of Texas at Arlington team up withMaggie Hunterof the USGS part in Fort Lauderdale to look for grounds of what is call rapid version , which might be thought of as an up - pace interpretation ofDarwinian phylogeny .
They examined the DNA of these subsister ophidian to see if there were any transmitted hint as to why certain pythons were able to withstand an extended freeze ; more precisely , they compare the deoxyribonucleic acid of python that lived before the halt case with the desoxyribonucleic acid of Python that had live to see if they could identify any departure that might explain the resiliency of the survivors at the molecular stage .
The short and distressing ( although not definitive ) answer was : yes .
The offspring of the surviving Burmese pythons likely inherited their parents' cold-adapted genes.
It sprain out that the survivors seemed to share genetic changes in areas of their genomes known to control thermoregulatory behaviour and metabolic process . " We saw a lot of things that just as luck would have it overlapped with a lot of the same sorts of pathways and cistron that we were studying in analog , in a much more control way , using more lab experiments in Todd ’s work on Burmese Python , " Card tell me . " As we delved into them , we start to see a lot of genes that are affect in thing like thermal tolerance . "
The finding , published in 2018 , suggest that the survivor share variations in their familial makeup that seemed to confer not bad stale tolerance and greater metabolic flexibility — two traits that Castoe ’s research laboratory had been investigating since 2011 . These snakes were more inclined behaviorally to seek shelter in undercover refugia to outlast the cold — a good adaptation to the environmental world of occasional freeze . And the metabolic changes seemed to favor a behaviour that encouraged small and more frequent meals — a good version to the ecologic reality that , having already decimated population of large mammals in the Everglades , the python might need to modify their dieting .
This is not classic news show — the study was small , no one ( surprisingly ) has be up on it , and , as Card put it , researcher still only have a scene from 30,000 feet of what happened on the genetic stratum in the python that outlive the heavy Freeze . Whatever it is , the transmitted change — or , more accurately , theselectionfor genes that enhanced endurance — appears to have pass off very quickly . And that is , possibly , very bad news show . It suggest that the pythons are on the move , genetically as well as geographically .
The implication is that the 2010 freeze act as a huge selection event , as evolutionary life scientist put it — an environmental stress so frightening , so extreme , that it has the effect of apace winnow out somebody carry a spoilt transmitted hand and " selecting " the lucky ones that check gain ground genic hands .
The frost culled out soul that were susceptible to dusty temperature and selected somebody that possess , at the genic story , some form of cold - hardiness . Those genes were presumptively passed down — right away , dissolutely and of course , cryptically — to their hundreds of offspring .
The proposition of rapid adaptation in the Burmese python universe in Florida again contradicts our traditional notion ofevolutionas a glacial process of genetic selection and refinement that requires millennia , eons and geologic epoch . " We typically intend of phylogeny as occurring over generally quite long clock time scale , on the order of several generations at the low end up to potentially thousands to trillion of years , " Card said . " I think with a mass of the instrument that we ’ve developed more of late , specially in things like genomics , people have take on a harder look at how quickly phylogenesis can occur … And generally , when you see such an uttermost affair occurring , it really paint a picture that there ’s very strong selection . Something ’s happening . "
In fact , Castoe believe theimportation of so many pythonsfrom so many dissimilar regions of Asia — all pack in their biologic luggage a wide variety of genetic variants , known as allele , for their head trip to North America — set the tabular array for a speedy genetic version . As Castoe put it : " If you ’ve set about a good amount of genetic variation , give strong selection , this can materialize in a heartbeat . ' If I ’ve commence the allelomorph , what the hell am I waiting for ? I ai n’t waiting for nothing ! ' "
At a meter whenroughly 40%of Americans do not accept the notion of evolution , the pythons that survived the Big Freeze in Florida come along to consider in it 100 % . The take - home genomics message from the snakes is that evolution is real , it ’s ostensibly happening at blindingly fast swiftness , and it fence that the 2010 cold elasticity may have create a subset of pythons better able to hold out cold temperature — and thus better adapted to spread beyond the northerly bounds of its current kitchen stove .
extract fromSLITHER : How Nature ’s Most Maligned Creatures Illuminate Our World © 2025 Stephen S. Hall and reissue by license from Grand Central Publishing / Hachette Book Group .
Slither : How Nature ’s Most Maligned Creatures Illuminate Our World Hardcover — $ 33.55 on Amazon
A spellbinding scientific and ethnic study of snakes , the enchantment and fear they inspire , and how surprising new science is indelibly changing our perception of these sensational and frightening creatures .
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