EVOLUTION IN OUR TIME


I was puzzled when I found  this frog at Grand River Terraces, one of the Cleveland Museum of Natural History’s protected Natural Areas.   Though it had the smooth skin and elongated body and legs I associate with a Green Frog, this little guy wasn’t green.

So I showed it to Brett Rodstrom, Northeastern Field Director of the Land Conservancy, and he told me it was indeed a Green Frog.  He said that for generations, these Green Frogs had been breeding in an area where the soil was very dark.  Being bright green, they were easy pickings for herons and raccoons against the dark background.  Through Natural Selection, the froggies that survived to go acourtin’ and abreedin’ another day were the dark ones.

One of the most famous examples of Natural Selection and protective coloration occurred in England during the 19th Century.  The Peppered Moth looked like what its name suggests.  Its permanent coloration protected it by mimicking the backgrounds it rested on.

When the resulting smoke and soot from the Industrial Revolution blanketed the area, only darker moths survived and bred.  Ultimately, the moth population became soot-black.

In the 20th Century,  environmentalists pushed for cleaner air in manufacturing areas.  As the landscape became cleaner,  the moth population evolved back to its original salt and pepper coloration.

Whatever the changes to its environment, species have a strong urge to survive.  I’m intrigued by the ones that are successful.

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