Natures wonders: taste mimicry fools predators (Introduction)

by David Turell , Sunday, February 24, 2019, 22:41 (2097 days ago) @ David Turell

In this case two butterfly species look alike because one tastes bad and since predators can't distinguish between them, the copycat doesn't get eaten. But there is a twist:

https://www.sciencedaily.com/releases/2019/02/190222101314.htm

"The viceroy butterfly is a mimic, modeling its orange-and-black colors after the queen butterfly, a bug that tastes so disgusting predators have learned not to eat it or anything that looks like it, including viceroys. The apparent dependence of mimics on their models made biologists wonder if the fates of the two species are forever intertwined. If so, then what happens when the mimic and the model part ways?

"A study recently published in Communications Biology and led by Katy Prudic, an assistant professor in the College of Agriculture and Life Sciences at the University of Arizona, has found an interesting answer. Viceroy butterflies living in northern Florida, far away from the southern-dwelling queen butterflies, are not only more abundant than their southern kin, but they have also developed their own foul flavor.

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"All over Florida, the viceroy caterpillar feeds on the same kind of plant: the Carolina willow. The tree arms itself against pests with phenolic glycosides, chemical relatives of aspirin.

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"The classical theory, called Batesian mimicry, posits that one animal, known as the mimic, looks like another animal -- the model that predators recognize as "unpalatable." An unpleasant experience trying to munch on the model species convinces predators to avoid both species, since they cannot reliably tell the difference between the two.

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"Prudic's study found that the viceroy thrives where the queen is not found, because it has evolved the ability to taste bad.

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"This discovery changes the way biologists must think about mimicry.

"The relationship between viceroy and queen butterflies once fell into the Batesian mimicry category, but when one of Prudic's co-authors, David Ritland, first discovered that viceroys had the ability to be nasty, the butterflies' relationship was recategorized as "Mullerian." There are no models in this mimicry theory, only "co-mimics:" two different animals that look the same and are both unpalatable.

"But Prudic's study proves that the viceroy butterfly does not fit neatly into either mimicry category."

Comment: Amazing change. Butterflies don't eat each other, so how would the mimic even know the other tasted so bad and start making the noxious chemical, which is related to aspirin?
Even the trees that are nibbled on use similar compounds to drive off the insects. Trees and insects are not related. Is this a pattern or convergence built into the instructions for evolution.