Evolution in action? African fish could be providing rare example of forming two separate species

Cornell University ^ | 01 June 2006 | Sara Ball

[PatrickHenry]

Avoiding quicksand along the banks of the Ivindo River in Gabon, Cornell neurobiologists armed with oscilloscopes search for shapes and patterns of electricity created by fish in the water.

They know from their previous research that the various groups of local electric fish have different DNA, different communication patterns and won't mate with each other. However, they now have found a case where two types of electric signals come from fish that have the same DNA.

The researchers' conclusion: The fish appear to be on the verge of forming two separate species.

"We think we are seeing evolution in action," said Matt Arnegard, a neurobiology postdoctoral researcher in the laboratory of Carl Hopkins, Cornell professor of neurobiology and behavior, who has been recording electric fish in Gabon since the 1970s.

The research, published in the June issue of the Journal of Experimental Biology, describes how some of these fish violate an otherwise regular pattern of mating behavior, and so could be living examples of a species of fish diverging into separate species.

Although these fish look alike and have the same DNA genetic makeup, they have very different electrical signals and will only mate with fish that produce the same signals. Cornell researchers believe that these different electrical signals are the fishes' first step in diverging into separate species.

The electric fish -- known as mormyrids -- emit weak electric fields from a batterylike organ in their tails to sense their surroundings and communicate with other fish. Each species of mormyrid gives off a single characteristic electric impulse resulting in the flash of signals, indicating, for example, aggression, courtship and fear. While the fish may be able to understand other species' impulses, said Arnegard, "They seem to only choose to mate with other fish having the same signature waveform as their own."

Except for some, Arnegard has discovered.

When he joined Hopkins' lab, the team was about to publish descriptions of two separate species. But when Arnegard decided to take a genetic look at these particular fish, he couldn't find any differences in their DNA sequences.

"These fish have different signals and different appearances, so we were surprised to find no detectable variation in the genetic markers we studied," Arnegard said.

Because all of the 20 or so species of mormyrid have distinct electric signals, Arnegard believes the different impulses of the fish he studies might be their first step in diverging into different species.

"This might be a snapshot of evolution," Arnegard said.

Understanding how animals become different species, a process known as speciation, is a major concern in understanding evolution. Arnegard's fish may allow researchers to test if a specific type of speciation is possible.

One common type of speciation is geographically dependent. Animals diverge into separate species because they become physically isolated from each other. Eventually, genes within each group mutate so that the groups can no longer be considered to be of the same species.

Another type of speciation, which many scientists have found harder to imagine, involves animals that live in the same geographic location but, for some reason, begin to mate selectively and form distinct groups and, ultimately, separate species. This so-called sympatric speciation is more controversial because there have been few accepted examples of it to date.

"Many scientists claim it's not feasible," Arnegard said. "But it could be a detection problem because speciation occurs over so many generations." These Gabon fishes' impulses, however, can change very quickly in comparison. So Arnegard suspects that the different shapes of the electric impulses from these mormyrids might be a first step in sympatric speciation.

One the other hand, the fish could be a single species. "This could be just a polymorphism, like eye color in humans, that violates the fishes' general evolutionary pattern but doesn't give rise to separate species," said Arnegard, who will return to Gabon in June to conduct further tests, funded by the National Geographic Society.

[Ethan Clive Osgoode]

Is it a random process?

Judging from what you wrote about randomness and determinism, I get the impression you are quite confused about these things. Just what, exactly, do you imagine a "random process" to be? After you explain that, maybe I can diagnose the source of your confusion, and cure you.

[Dimensio]

Just what, exactly, do you imagine a "random process" to be?

With respect to mutation, random means that no one permutation is any more likely to occur than another.

[Ethan Clive Osgoode]

random means that no one permutation is any more likely to occur than another.

So according to you, a process which assigns probabilities to events A and B out of the set {A, B} like so...

p(A) = 0.5
p(B) = 0.5

would be "random". Presumably then, you believe that a process which assigns probabilities to A and B like so...

p(A) = 0.3
p(B) = 0.7

is not "random" and is "deterministic". Yes?

[metmom]

Correct. Mutations create random variants of offspring from a parent generation of an organism, however the process of natural selection, which acts as a filter upon the variants, is nonrandom, producing a deterministic result.

But the *natural selection* that occurs is random also. The environmental *pressures* that come to bear on a species that would wipe out the ones that didn't have the appropriate mutation to survive are random. And just what are the chances that the exact mutation needed to survive should happen to occur at just the right time, and be passed on long enough, so that when the change needed to select it out happened, it would be selected and the change would occur?

Mutations create random variants of offspring from a parent generation of an organism, however the process of natural selection, which acts as a filter upon the variants, is nonrandom, producing a deterministic result.

And try as one can, it still sounds like if there is some kind of *mechanism* behind something, there is intelligence behind it also. How can a *mechanism* arise from chaos?

[taxesareforever]

Fossils, as physical objects, are data points. Physical objects may be used to derive explanations, but physical objects themselves are not explanations.

So why does the theory of evolution use fossils as sources of timeline? If they aren't explanations why are they used as such?

[metmom]

Why would you ask if a word denoting an explanation would apply to a physical object? Physical objects themselves are not explanations.

That's right, but the issue isn't with the physical objects, it's with the interpretation, or rather misinterpretation, of what they suggest.

[Dimensio]

Presumably then, you believe that a process which assigns probabilities to A and B like so...
p(A) = 0.3
p(B) = 0.7
is not "random" and is "deterministic". Yes?

No. I do not believe that natural selection is analagous to such a process.

[Dimensio]

That's right, but the issue isn't with the physical objects, it's with the interpretation, or rather misinterpretation, of what they suggest.

Then taxesareforever should have stated as much. He did not; he only asked regarding the fossils themselves.

[js1138]

So why does the theory of evolution use fossils as sources of timeline?

Why do people use the appearance of their house to tell when they are home, rather than the more objective data provided by a GPS device?

Fossils are not a source of dating, but they are a quick way of identifying strata that have been dated by other means.

There are many independent ways of dating geological objects. If you think they lead to inconsistencies, go forth and win your Nobel Prize.

[Dimensio]

But the *natural selection* that occurs is random also. The environmental *pressures* that come to bear on a species that would wipe out the ones that didn't have the appropriate mutation to survive are random.

The result of environmental conditions upon genetic diversity is not random. That is why natural selection is said to be nonrandom.

And just what are the chances that the exact mutation needed to survive should happen to occur at just the right time, and be passed on long enough, so that when the change needed to select it out happened, it would be selected and the change would occur?

Are you suggesting that only one possible mutation can allow a species to survive within a given environment? If not, then I do not understand the purpose of this question. If so, then you are mistaken.

And try as one can, it still sounds like if there is some kind of *mechanism* behind something, there is intelligence behind it also. How can a *mechanism* arise from chaos?

To what "chaos" do you refer? The mechanism ultimately occurs as a result of the fundamental properties of the universe.

[metmom]

Now here is an interesting problem. Take this Laotian rock rat for example, the one that was thought to be extinct. It was believed to have become extinct some 11 million years ago. Now, how has it remained unchanged for all that time? Has the environment remained stable for that entire length of time? Have there been NO mutations at all and if not why? What about the dating of all the rock rat fossils? If it was believed to have been extinct, then any fossil younger than 11 million years was dated wrong. So what about other fossils found in the proximity of the misdated ones? hmmmm..

[Dimensio]

So why does the theory of evolution use fossils as sources of timeline?

It is the determined dates -- or relative dates -- of fossils that are used as one source for generating evolutionary timelines.

If they aren't explanations why are they used as such?

The fossil ages are used as such. Without a means of determining the ages, the fossils would not be usable in such a fashion. The fossil ages are used as the explanation, not the fossils themselves.

[Dimensio]

Take this Laotian rock rat for example, the one that was thought to be extinct. It was believed to have become extinct some 11 million years ago. Now, how has it remained unchanged for all that time?

If the rat has indeed remained completely unchanged, then it is a result of the species finding a successful niche where hereditary changes that would have led to alteration of the species were less successful than stasis for the species.

[metmom]

If so, then you are mistaken.

Isn't it hard to be right all the time? I mean really, everybody on this thread is *mistaken* in some way or another except one, apparently.

The mechanism ultimately occurs as a result of the fundamental properties of the universe.

So where did the fundamental properties of the universe come from? This goes back to assuming that order can exist without intelligence behind it. One cannot use the conclusion one is trying to *prove* the basis for the argument to prove it. The fact that there is order in the universe is not proof that intelligence is not required for order, because one would have to know that there was no intelligence behind the universe in order for that argument to work and no one can know it. Precedent is that order and complexity require intelligence; there is no precedent that supports that order can arise without intelligence.

The result of environmental conditions upon genetic diversity is not random.

And what exactly does that mean? Mutations occur randomly, the environmental changes that occur are ramdon, so how is any part of the process not random?

[RunningWolf]

About the extinct rat thats not. Well it should throw at least a couple conclusions into doubt.., nah

Wolf

[Dimensio]

Isn't it hard to be right all the time? I mean really, everybody on this thread is *mistaken* in some way or another except one, apparently.

I have been corrected on subjects in previous discussions. I am willing to listen to explanations of why statements that I make are in error.

So where did the fundamental properties of the universe come from?

I do not know. Lacking any evidence on the subject, I draw no conclusions.

This goes back to assuming that order can exist without intelligence behind it.

You have not demonstrated that order is required. Given a lack of information on the subject, the safest assumption is to make no assumptions of extraneous entities.

One cannot use the conclusion one is trying to *prove* the basis for the argument to prove it.

I have claimed no proof. I believe that I have stated this previously, so I do not understand your assertion that I am attempting to prove anything.

The fact that there is order in the universe is not proof that intelligence is not required for order, because one would have to know that there was no intelligence behind the universe in order for that argument to work and no one can know it.

I do not claim to have proven that no intelligence exists behind the order of the universe. I only state that thus far no evidence has been presented to show that intelligence is behind the order of the universe.

Precedent is that order and complexity require intelligence; there is no precedent that supports that order can arise without intelligence.

Your conclusion is not logical. You are claiming that there can exist no known situation where order occurs without intelligence as a means of ruling out all instances where order occurs without any apparent intelligence. You have only determined that it is impossible to establish prescedent, because the vast majority of cases where order occurs are situations where there is no apparent intelligence but also no means of ruling out intelligence, thus there is no means of drawing any conclusion.

And what exactly does that mean? Mutations occur randomly, the environmental changes that occur are ramdon, so how is any part of the process not random?

Natural selection is not itself the process of mutation or environmental shifting. Natural selection is the result of varied organisms having varied reproductive successes based upon heriditable traits within a specific environment

[Ethan Clive Osgoode]

No.

You said:

random means that no one permutation is any more likely to occur than another.

Now, if some permutations are more likely than others, is that random or not random?

[metmom]

There is a basis, or precedent, for concluding that order requires intelligance because we see that in the manmade world around us. Everything that was altered from it's natural state by humans had intelligence behind it. All the things you are currently surrounded by, were a product of intelligence. Just because the universe and *nature* are *natural* doens't mean that the same concept cannot be applied; that the order and complexity are a result of intelligence. It's not illogical at all to deduce that.

What is illogical is to deduce that order can arise from non-order, on it's own, with no *mechanism* to produce order. And if there was a mechanism, that in itself would indicate intelligence. There is no basis for assuming that order can arise from non order, or chaos. It is illogical to assume so when there is no basis for it.

That's the evidence for intelligent design. It's scientific because it can be observed and reproduced and data can be got from it.

[metmom]

I have been corrected on subjects in previous discussions. I am willing to listen to explanations of why statements that I make are in error.

Which is not the same at all as constantly telling people they are wrong, mistaken, in error, however it's worded about everything they post.

[taxesareforever]

You have only determined that it is impossible to establish prescedent, because the vast majority of cases where order occurs are situations where there is no apparent intelligence but also no means of ruling out intelligence, thus there is no means of drawing any conclusion.

"because the vast majority of cases where order occurs are situations where there is no apparent intelligence

Please be specific and give a number of these cases.