Electric Fish on Verge of Evolutionary Split

[tocqueville]

Robert Roy Britt
LiveScience Managing Editor
LiveScience.com
Sat Jun 3, 11:00 AM ET

Electric fish emit weak signals from an organ in their tails that serves as a battery. Different emissions signal aggression, fear or courtship.

While the fish can apparently understand each others' warning signals, "They seem to only choose to mate with other fish having the same signature waveform as their own," explains neurobiologist Matt Arnegard of Cornell University.

But in the Ivindo River in Gabon, Arnegard and colleagues have found fish with the same DNA emitting distinctly different signals. The fish are likely on the verge of splitting into two species, the researchers announced today.

"We think we are seeing evolution in action," Arnegard said.

http://news.yahoo.com/s/space/20060603/sc_space/electricfishonvergeofevolutionarysplit

[Craig3410]

1. Silly librul; God's makin' dem fishies split paths!

Evoulutoin is a lie!!1

Seriously, this is cool; have we ever seen evolution actually happen in such a short timeframe?

[eppur_se_muova]

2. Yes. The famous case of English moths evolving from mostly white to

mostly gray to match the color of tree bark as pollution increased.

Coyotes in easterna Canada/Maine have migrated into territories formerly occupied by wolves (wiped out by hunters & traps) and have evolved into more robust variants whose larger, stronger skulls are virtually indistinguishable from wolves -- big enough now to attack moose.

Read both of these long ago, on things like printed paper, not Web sites, so no links, sorry.

/oops, meant to reply to OP, sorry 'bout that.

[DavidDvorkin]

3. The moths have now evolved back to mostly white

because of reduced pollution. I read of this recently. It's a further confirmation of the effect of selection.

[Nihil]

4. "Evolved"?

> It's a further confirmation of the effect of selection.

This bit I agree with but "evolved"?

There has been no speciation here, merely a difference in
the distribution of colour variants over a few centuries
(from light to dark and now back again).

It's like saying that people "evolved" to being fat when there
was no threat that required them to run away but "evolved" back
to thin when they had to start running around again.

[trotsky]

5. If you go with the generic definition of evolution, which is

"change in allele frequency in a population over time", then yes, the moths were undergoing evolution.

[DavidDvorkin]

6. Exactly.

Evolutions is more than speciation.

[Nihil]

9. Apologies

I thought that "selection" was the "change in allele frequency in a
population over time" aspect while "evolution" required speciation.

Learn & live!

[trotsky]

10. No apologies necessary!

It's easy to get confused, especially since mainstream sources pretty much merge the two.

[eppur_se_muova]

7. "Evolution" doesn't *necessarily* mean speciation -- so to your original

question, perhaps I should say "There are no cases I'm aware of where divergent species, incapable of interbreeding with each other, have emerged from one species within the time that humans have been observing them." Specialists may very well know of examples among microorganisms, for example, where the time between generations is very small. The thing which makes it so hard to observe evolution directly is the long lifetimes and slow generational turnover of most larger species. When a generation is only an hour long, evolution can be used as an experimental tool, churning out variant strains like mass production. But whether anyone has ever pushed this to the degree of obtaining variant species, I don't know.

[eppur_se_muova]

8. AC & DC ?

couldn't resist.:evilgrin: