Monday, June 04, 2012

Peacocks and zebrafish

Ah, now there's an unlikely combination. Peacocks and zebrafish. Why am I rolling them out this morning?

Because they are two players in the 24 May issue of Nature.

First, peacocks. The undisputed masters of ostentation. The poster boys for male foppery. The over-the-top excess of alpha showoffery you get when sexual selection runs crazily amok.

There seems to be no dispute that peahens go for the flamboyant tails. But at what cost to the peacock? That fabulous fan of feathers requires energy to produce, energy that might reasonably be put to more effective use, such as beefing up to battle competitors. And imagine trying to escape a predator with that billowing sail to slow you down.

So what's the deal? The question has exacerbated biologists since Darwin. As described in a new edition of Davies, Krebs and West's classic text on behavior ecology (reviewed in Nature), the peacock's tail may signal genetic resistance against the prevalent disease that infects the species, on the grounds that sick individuals would not have the resources to produce such frippery.

Love my feathers, love my genes. The peacock holds its place as the iconic emblem of sexual selection.

And zebrafish?

Well, actually it's larval zebrafish I have in mind, with two characteristics that endear them to neurologists: they have small brains, and they are transparent.

Now I don't pretend to understand the article on "Brain-wide neuronal dynamics during motor adaptation in zebrafish." I can only make a wild guess of what is meant by "vestibular, proprioceptive and somatosensory feedback," for example. But I get the drift.

Our researchers paralyzed larval zebrafish and put them into a virtual dynamic environment where they could react to sensory input. The fish were genetically modified to produce a fluorescent chemical indicator that lights up active brain cells.

And here they are in the pages of Nature, their full brains responding to changes in their fictive environments. Says Nature of the research: "In no other vertebrate animal model is it possible to accomplish cellular-level-resolution imaging of the entire brain."

I wish I knew enough about this stuff to say something sensible. I only know something important is going on, a vestibular inching in on the century of the brain. And I love those little transparent fish brains, glowing gorgeously as the fish navigate their virtual "video-game" world.