Comments on: From 250 million years of repression, a wonderland of hats

By: Zen Faulkes

Zen Faulkes — Tue, 17 Jan 2012 22:14:09 +0000

A new paper disputes this hypothesis:

Mikó I, Friedrich F, Yoder MJ, Hines HM, Deitz LL, Bertone MA, Seltmann KC, Wallace MS, Deans AR. 2012. On dorsal prothoracic appendages in treehoppers (Hemiptera: Membracidae) and the nature of morphological evidence. PLoS ONE 7(1): e30137.

DOI: 10.1371/journal.pone.0030137

By: Li

Li — Mon, 09 May 2011 15:16:24 +0000

It is very interesting that treehoppers can discard their helmets to escape. I think the bugs would survive without helmets at least in a short time. Has the wing-like appendage regeneration capacity?

By: Alex

Alex — Fri, 06 May 2011 07:52:32 +0000

Cool, I guess I certainly shouldn’t be surprised at insects getting there first with magnificent handicap displays. I study the origins of domestication and insects beat us to that by, oh, around 50 million years too.

By: Ed Yong

Ed Yong — Thu, 05 May 2011 18:41:05 +0000

“Apart from those cool antler flies does anyone know of strange appendages being the product of sexual selection in insects?”

http://en.wikipedia.org/wiki/Giraffe_weevil

By: Alex

Alex — Thu, 05 May 2011 18:01:43 +0000

Agreed that these look more like predator defence through mimicry or being potentially toxic and unpalatable. Plus I think such insects are more likely to use pheremonal cues for sexual selection, or more obvious signals such as being larger than the other guy. Ornate non-functional appendages seem more the realm of avian and mammalian sexual selection, but I could be wrong. Apart from those cool antler flies does anyone know of strange appendages being the product of sexual selection in insects? Is the handicap principle generally for larger organisms?

By: Alex

Alex — Thu, 05 May 2011 17:58:39 +0000

Wow, the diversity of shapes here is really amazing, the treehopper’s take on an ant is fantastic, all the essential elements of an ant without quite being like an ant, evolutionary art!

By: Robert S-R

Robert S-R — Thu, 05 May 2011 16:55:07 +0000

I don’t think any of the helmets are really flamboyant advertisements for sex. Even the most extravagant ones look like dead leaves, fungi, or flat-out warning signs to predators.

By: Alex Wild

Alex Wild — Thu, 05 May 2011 16:39:31 +0000

Dan (#8)-

Membracids apparently emerge from within the enormous family Cicadellidae, the leafhoppers & sharpshooters, although from what I understand, the precise nature of the non-monophyly is not clear enough yet to be able to resolve the taxonomic issues. In any case, the best outgroup for comparison will be a leafhopper.

By: Eleanor

Eleanor — Thu, 05 May 2011 10:04:30 +0000

Indeed it does look like the Ascot of the insect world. Didn’t I see Heteronotus at the royal wedding?

Of course, as the author points out, answering the question “what is the head-gear used for now?” doesn’t really answer the question of “what was it used for then?”. How it arises in the first place is the really tricky bit.

By: Dan Smith

Dan Smith — Thu, 05 May 2011 09:53:24 +0000

I wonder what the closest outgroup is (cicadas?). Resequencing and a phylogeny would be really interesting. Makes you wonder whether T1 in drosophila could similarly be induced to make helmets when this is understood. The receptiveness to fusion in the helmet primordia is interesting, wings mustn’t fuse & aberrant fusion is a live clinical issue (eg cleft palate, hypospadia).

Sexual selection would imply sexual dimorphism and likely a fitness cost (I’m so great I can wear an ‘eat me’ hat and survive). I can’t see any reference to this being sex linked in the paper (and it would surely have said). The examples that strongly suggest ant mimicry imply that it is selected for (ants being less palatable and possibly protected by formic acid) but several things may be going on across the group.