Sunday, April 19, 2015

Open and Shut

Photos by Bob Wenrick 3/25/2015

"I'm really a Red-spotted Purple."

This butterfly looks very much like a Pipevine Swallowtail. (That's what I claimed when I first laid eyes on him/her.) In fact, this is a Red-spotted Purple, a mimic of the Pipevine Swallowtail. How does that work?
Pipevine Swallowtail caterpillars eat - you guessed it - the poisonous Pipevine plants (Aristolochia watsonii). That food makes them taste nasty and be poisonous, to boot. Any predator who eats the butterfly once, learns to avoid all of them in the future. If another animal (in this case, the Red-spotted Purple) looks similar enough, that animal will also be avoided by predators. (Even though the Red-spotted Purple is perfectly non-toxic.) More of the mimics will survive to reproduce, and their genetic info will spread through the population. Evolution through natural selection. And that's a fact.

No comments:

Post a Comment