Some Turtle Ant Mimics

Biologist Henry Hespenheide sends along this shot of several ant-mimicking beetles and their Cephalotes model:

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What I take from this image is just how important the appearance of a narrow waist must be to successfully pulling off the illusion. These mimics differ considerably in body proportions, but they have all managed to paint a fake waist on their elytra.

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For the buprestid in the upper right corner (Agrilus ornatulus), the mimicry association was first proposed by Vogt (1949), who stated the species' appearance was suggestive of Cephalotes angustus, which occurs commonly on the the beetle's host shrubs in south Texas.

Doesn't this kind of suggest there's a bit more going on than natural selection?

By MrILoveTheAnts (not verified) on 20 May 2010 #permalink

Do we know what the advantage of the mimicry might be? My (thoroughly uninformed) impression was that most ants care a great deal more about scent than sight, and I'm not sure how effective those waist-markings would be at eye level anyway. Do relevant aerial predators avoid ants but chow down on unmarked beetles?

Yeah this doesn't seem to be mimicry, but rather convergent evolution in appearance. Those insects happen to have the same coloration and similar body shape, a shape which is extremely common for insects.

I love the clerid-- looks like he's wearing a Cosby sweater. Any idea which family the guy in the middle of the bottom row belongs to?

By Ainsley S (not verified) on 20 May 2010 #permalink

There is good reason to believe this is mimicry, as a defense against predation by vertebrates - namely birds and lizards. These visual hunters, when young and naive, having nabbed an ant, soon realize it is not a good meal, thereafter avoid eating ants or things that appear to be them. It seems to be quite straight-forward natural selection for not getting eaten, and has nothing to do with hiding among ants in their nests, which would be dangerous places, indeed, for most or all of these mimics to go. Myrmecophily and avoiding being eaten by ants take on very different forms than the sort of mimicry pictured here.

By James C. Trager (not verified) on 21 May 2010 #permalink

There is good reason to believe this is mimicry, as a defense against predation by vertebrates - namely birds and lizards. These visual hunters, when young and naive, having nabbed an ant, soon realize it is not a good meal, thereafter avoid eating ants or things that appear to be them. It seems to be quite straight-forward natural selection for not getting eaten, and has nothing to do with hiding among ants in their nests, which would be dangerous places, indeed, for most or all of these mimics to go. Myrmecophily and avoiding being eaten by ants take on very different forms than the sort of mimicry pictured here.

By James C. Trager (not verified) on 21 May 2010 #permalink

There is good reason to believe this is mimicry, as a defense against predation by vertebrates - namely birds and lizards. These visual hunters, when young and naive, having nabbed an ant, soon realize it is not a good meal, thereafter avoid eating ants or things that appear to be them. It seems to be quite straight-forward natural selection for not getting eaten, and has nothing to do with hiding among ants in their nests, which would be dangerous places, indeed, for most or all of these mimics to go. Myrmecophily and avoiding being eaten by ants take on very different forms than the sort of mimicry pictured here.

By James C. Trager (not verified) on 21 May 2010 #permalink

James C. Trager @7 (and 8... and 9): Thanks!

James, you got papers discussing those claims? Please share.

This mimicry complex is discussed at length here:

Hespenheide, H. A. 1986. Mimicry of Ants of the Genus Zacryptocerus (Hymenoptera: Formicidae). Journal of the New York Entomological Society 94: 394-408.

The argument that the ants serve as a model in a mimicry complex is this:

1. The ants are much more abundant than the beetles.
2. The beetles are usually collected near the ants.
3. Ants aren't good eating, generally speaking (high chitin-to-fat ratio; often with nasty chemicals).
4. These particular ants are basically standard-issue Cephalotes (formerly Zacryptocerus) without obvious visual modifications from related species, while the beetles are colored rather differently from their close relatives, suggesting selection for a pattern similar to the ants.

Granted, this is circumstantial evidence. But it's hard to imagine what else might be behind the convergence.

Sorry about the multiple posts - Damn iPhone!

Thansk for posting the ref.!

By James C. Trager (not verified) on 21 May 2010 #permalink

I'd also like to thank the skeptics for having the courage to stand up to the entymological/industrial complex (or "Big Ant", as it's commonly known) and the lackeys who mindlessly promote its agenda.

Seriously, I'm new to the comments here. I like questioning and challenging blog authors, because hey, that's what the format is for. But what's with all the aggression and snark? Creationist trolls or just socially maladjusted pedants?