evolving...but aren't we all

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On a recent walk, I noticed this young fence lizard, a medium sized species found along forest edges, rock piles and rotting logs or stumps.

Eastern fence lizards can grow to be 7.25 inches long, but this young one was hardly bigger than half a Tootsie-Roll.

Farther south, fence lizards are evolving quickly because of attacks by introduced fire ants. The tenacious ants try to lift up the scales on the soft underbelly of the lizard and inject a toxic neuromuscular venom that can kill the reptile in under a minute. In turn, the besieged lizards are adapting through the rapid evolution of longer legs to escape the ants. 


Evolution is driven by environmental changes. Lizards with slightly longer legs survive the ant attacks at a higher rate thus living longer and producing more offspring that also have the advantageous leggy tract.

Fire ants are not a real problem in my region, (at least yet) so our fence lizards still have short legs. In time, will we see them separate into two species: long-legged fence lizard and short-legged fence lizard. Perhaps, that's how speciation works with the ultimate range of the fire ants being the determinate factor.  

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