Thursday, October 1, 2015

Common buckeye? Hardly

I always somewhat cringe when the word "common" is used in the common name of a living thing: common milkweed, common loon, common smartweed common sandpiper (well, hardly in East Tennessee!), common cold. Such is the case with the Common Buckeye, a rather spectacular butterfly we found on our "Butter-FlyAway" last Sunday.

We didn't see a lot of plantain or snapdragons, their host plants, but we did find one, and only one, buckeye. It was simply feeding on the blooming sedum by the Ijams greenhouse. 

Common it isn't. Buckeyes exhibit seasonal polyphenism

Polyphenism is the phenomenon where two or more distinct phenotypes (observable features: eye color, leg length, face shape, etc.) are produced by the same set of genes. In other words, there are portions of genotype that produce two different colors in succeeding generations. Different pigmentation patterns can provide appropriate camouflage throughout the changing seasons, as well as alter heat retention as temperatures change. In birds, the tundra-living willow ptarmigan is chestnut brown in summer, white in winter, all to blend into its environs.

In the case of the buckeye butterflies, the underside of their wings change a bit in color from the summer brood to the fall brood, from yellow to a rosy pink. But unlike the ptarmigan, it's in alternating generations. Summer parent yellow, autumn offspring pink, next summer's first brood, yellow again.

Why would this be? Probably to better blend into the two seasonal environments. Yellow in summer, pink in autumn. Or, do the fall tones simply hold in more heat on cooler days?

Now, what is common about any of this?

Of course, when you look at it, you don't readily notice its clever genetic switcheroo, but it's that same set of genes that do code for the wonderful eye spots this species is known for. That we do notice.

For a look at our Butter-FlyAway at Ijams, click: Buttery. 

Butter FlyAwayers in search of butterflies

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