Scientists Discover Fish in Act of Evolution in Africa

[SeanCallan]

"In what could be a first in the world, a fish species known as cichlids has been observed by scientists in the act of splitting into two distinct species in Lake Victoria, Africa

[dshnarw]

It's an interesting read, but unfortunately mislabeled. The original Nature article never describes this change as "evolution", but as adaptation.

 

Nevertheless, a cool thing to see...we aren't killing everything!!

[MOT]

isn't adaptation a factor in evolution? please explain

[SeanCallan]

isn't adaptation a factor in evolution? please explain

 

I have to agree with MOT, adaption is a factor in evolution. Darwin's original observations were on the adaptations of the finches for the particular location on the islands and the food sources available.

 

"In biology, evolution is the changes seen in the inherited traits of a population from one generation to the next. These changes are relatively minor from one generation to the next, but accumulate with each subsequent generation and can eventually cause substantial changes in the organisms."

 

These changes are brought on the by the need to adapt to a changing environment. That's the basic survival of the fittest. You adapt or you die.

[dshnarw]

isn't adaptation a factor in evolution? please explain

 

Sure, it can be very important to the actual process of evolution. But it takes much more than simple adaptation to create a new species ("macroevolution"). There is no actual change in DNA exhibited in these fish (despite what the news article implies/tells you). What has been observed is a gene already present in the fish becoming more common because it helps them survive. Until there is an actual change (mutation) in the DNA, no new species.

 

Simply put, this is no different than the abundance of sickle cell trait in humans with African descent...a gene useless elsewhere became a very common gene in Africa because it fights certain diseases common only in Africa. Survival of the fittest/adaptation is that those with the sickle cell trait survived the diseases, while those without died. We don't consider humans of African descent to be a different species. Same thing is happening with these fish. An already occurring trait becomes more abundant, nothing more, nothing less.

[SeanCallan]

Sure, it can be very important to the actual process of evolution. But it takes much more than simple adaptation to create a new species ("macroevolution"). There is no actual change in DNA exhibited in these fish (despite what the news article implies/tells you). What has been observed is a gene already present in the fish becoming more common because it helps them survive. Until there is an actual change (mutation) in the DNA, no new species.

 

Simply put, this is no different than the abundance of sickle cell trait in humans with African descent...a gene useless elsewhere became a very common gene in Africa because it fights certain diseases common only in Africa. Survival of the fittest/adaptation is that those with the sickle cell trait survived the diseases, while those without died. We don't consider humans of African descent to be a different species. Same thing is happening with these fish. An already occurring trait becomes more abundant, nothing more, nothing less.

 

We don't consider them a different species because you'd be labeled a racist and killed. Additionally we never do subspecies within the human race, everyone gets labeled a Human. Darker coloring in humans, birds, moths, etc is considered an evolutionary trait.

 

Darwin observed Finches, all the same bird, who had adapted and evolved for their particular situation. But if we went by what you mentioned before, it wasn't evolution because they were still Birds.

[dshnarw]

We don't consider them a different species because you'd be labeled a racist and killed. Additionally we never do subspecies within the human race, everyone gets labeled a Human. Darker coloring in humans, birds, moths, etc is considered an evolutionary trait.

 

Darwin observed Finches, all the same bird, who had adapted and evolved for their particular situation. But if we went by what you mentioned before, it wasn't evolution because they were still Birds.

 

Please think about that entire statement...it is illogical. Humans are not different species simply because of the lack of genetic variation to produce different species. Do you really think scientists in Darwin's era were concerned with being called racist and being killed?

 

Darwin observed morphological differences within a **family** of birds. Compare that to the family humans are in - which includes all of the Great Apes. He observed differences on the scale of those found between humans and gorillas. I neither stated, nor implied that all birds were the same. I stated that tiny differences in eyesight alone were **not** evolution.

 

 

EDIT: Now that I've read the *entire* Nature article...the link you posted is misleading in a number of ways. The article is discussing two completely different species of fish, neither of which have evolved or adapted to a human-induced polluted environment. It merely compares the two species of fish - one of which has better eyesight - and their ability to live in polluted waters. Because of the better eyesight, the one species of fish is better adapted. The only *mention* of evolution that creeps into the article is that one fish species evolved from the other (millions of years prior) while still in contact with each other. This statement alone goes against Darwin's principles of evolution, which called for separation of a group of a species. The article, though, would have us believe that the fish are being pushed to evolve due to human activity. This is NOT the case - the fish already evolved millions of years ago, and now the better adapted one is surviving.

Edited October 8, 2008 by dshnarw

[MOT]

I think the author uses the word species liberally throughout this article. I am pretty sure that two member of a genus become separate species once they can no longer reproduce together and create viable offspring. The title says that scientists have discovered fish in "act of evolution", and I think that adaptation might be considered an "act of evolution". whatever that means. He might have been better titled; "Scientists' discovery illustrates the evolutionary process" or better yet "an "act of microevolution". I think his title catches one's attention, which is generally the purpose of titles in these kinds of websites. Did you guys read the comments below the article?!? pure ignorance

[SeanCallan]

Please think about that entire statement...it is illogical. Humans are not different species simply because of the lack of genetic variation to produce different species. Do you really think scientists in Darwin's era were concerned with being called racist and being killed?

No, I definitely don't think they'd be called racist, I was referring to our current time with our modern technology and abilities to analyze DNA. One of the greatest researcher of genetics was recently roasted when he suggested that those from the African continent were a subspecies, he came forward with his observations after reviewing the DNA and from simple observation (Compare the modern world to Africa). If I'm not mistaken, during Darwin's time they already thought those from Africa were inferior

 

I believe what I was trying to say can be demonstrated in the Pepper Moth. Anyone who has taken biology has heard about the Pepper Moth. In a relatively short span of time the Pepper Moth went from being light colored to darker to adapt changing conditions due to the rise in pollution from the industrial revolution. It remained the same species only with a morph.

 

The peppered moth is one of the most commonly used examples of evolution but it never involves the evolution into a new species.

 

All of this information is found in my very basic college biology book.

 

Darwin observed morphological differences within a **family** of birds. Compare that to the family humans are in - which includes all of the Great Apes. He observed differences on the scale of those found between humans and gorillas. I neither stated, nor implied that all birds were the same. I stated that tiny differences in eyesight alone were **not** evolution.

EDIT: Now that I've read the *entire* Nature article...the link you posted is misleading in a number of ways. The article is discussing two completely different species of fish, neither of which have evolved or adapted to a human-induced polluted environment. It merely compares the two species of fish - one of which has better eyesight - and their ability to live in polluted waters. Because of the better eyesight, the one species of fish is better adapted. The only *mention* of evolution that creeps into the article is that one fish species evolved from the other (millions of years prior) while still in contact with each other. This statement alone goes against Darwin's principles of evolution, which called for separation of a group of a species. The article, though, would have us believe that the fish are being pushed to evolve due to human activity. This is NOT the case - the fish already evolved millions of years ago, and now the better adapted one is surviving.

 

To some extent I see what you're saying, but this is survival of the fittest. Regardless of whether the initially adaptation occurred 10 years or 10 million years ago, the species, subspecies, or morph which is better adapted is surviving while the other's numbers are declining.

 

You're talking about geographical isolation which is only one time.

 

"Adaptations are structures or behaviors that enhance a specific function, causing organisms to become better at surviving and reproducing."

[OUsnakebyte]

Disclaimer - I have not read the Nature article; just wanted to comment on the use of wording here...

 

I have not seen in this entire thread the use of two very key words to describe what is happening: Natural Selection - or if you want to get really picky about it, you could distinguish natural from artificial selection. At any rate, what is happening with the cichlids, what happened with the Pepper Moth during the Industrial Revolution, etc. was natural selection - the most powerful driver of evolution, of which there are three (or four if you want to separate):

 

- Natural Selection

- Genetic Drift/Founder Effect

- Gene Mutation

 

Evolution does not happen in one or two generations, and we have certainly NOT seen speciation since the pollution started in this lake. The evolutionary time scale is geologic - millions of years.

 

The "Act of Evolution" that these fish are 'involved in' is merely Natural Selection (or if you want to consider human interference, whether intentional or unintentional, Artificial Selection) - quite possibly the most powerful biological process on Earth. Adaptations take evolutionary time to develop; the fish with better eyesight are being selected for due to the changes in their environment - nothing more.

 

 

Darwin is my hero - celebrate his 200th birthday this February 12, 2009!

 

Cheers

Mike

[SeanCallan]

Disclaimer - I have not read the Nature article; just wanted to comment on the use of wording here...

 

I have not seen in this entire thread the use of two very key words to describe what is happening: Natural Selection - or if you want to get really picky about it, you could distinguish natural from artificial selection. At any rate, what is happening with the cichlids, what happened with the Pepper Moth during the Industrial Revolution, etc. was natural selection - the most powerful driver of evolution, of which there are three (or four if you want to separate):

 

- Natural Selection

- Genetic Drift/Founder Effect

- Gene Mutation

 

Evolution does not happen in one or two generations, and we have certainly NOT seen speciation since the pollution started in this lake. The evolutionary time scale is geologic - millions of years.

 

The "Act of Evolution" that these fish are 'involved in' is merely Natural Selection (or if you want to consider human interference, whether intentional or unintentional, Artificial Selection) - quite possibly the most powerful biological process on Earth. Adaptations take evolutionary time to develop; the fish with better eyesight are being selected for due to the changes in their environment - nothing more.

Darwin is my hero - celebrate his 200th birthday this February 12, 2009!

 

Cheers

Mike

 

Fantastic post!

 

But I don't agree with your definition of evolutionary time being millions of years; bacteria and viruses can evolve rather quickly. Look at MSRA for example, H-E-double hockey sticks the Flu is a decent example. In only a matter of years they have evolved resistances to common medications.

 

As for Darwin's birthday? Keg party!

Edited October 9, 2008 by SeanCallan

[mogurnda]

Evolution does not happen in one or two generations, and we have certainly NOT seen speciation since the pollution started in this lake. The evolutionary time scale is geologic - millions of years.

Mike, if you haven't already read "Darwin's Dreampond" about speciation of the planktivorous cichlids in Lake Victoria before they got wiped out, I think you'd like it. It makes a strong argument for speciation on a much faster time scale. [edit: this is consistent with Gould's "punctuated equilibrium" model, in which speciation happens relatively quickly in response to environmental change.]

 

 

What has been observed is a gene already present in the fish becoming more common because it helps them survive. Until there is an actual change (mutation) in the DNA, no new species.

If you read "Origin of Species" (hard work, but worth it), Darwin argues that natural selection acts on naurally-occurring, pre-existing variation. There do not need to be any new mutations in the separated populations, just changes in allele frequencies that become fixed with time and selection.

[OUsnakebyte]

But I don't agree with your definition of evolutionary time being millions of years; bacteria and viruses can evolve rather quickly. Look at MSRA for example, H-E-double hockey sticks the Flu is a decent example. In only a matter of years they have evolved resistances to common medications.

 

As for Darwin's birthday? Keg party!

 

No, of course it doesn't always have to be millions of years; the quicker you can turn over your population, the more quickly those forces can act - elephants will "evolve" more slowly than bacteria, for example.

 

 

Mike, if you haven't already read "Darwin's Dreampond" about speciation of the planktivorous cichlids in Lake Victoria before they got wiped out, I think you'd like it. It makes a strong argument for speciation on a much faster time scale. [edit: this is consistent with Gould's "punctuated equilibrium" model, in which speciation happens relatively quickly in response to environmental change.]

 

Nope I have not, but you have just put it on my reading list. And yeah, I realize that's it's not always happening at the same rate (I actually thought about Gould's punctuated equilibrium when I wrote that - and Veron's Reticulate Evolution, since we are all coral lovers here... )

 

The point I was trying to make was that these fish have not evolved this better eyesight since the pollution started - it is the force of Natural Selection acting upon them - that's all.

 

 

If you read "Origin of Species" (hard work, but worth it), Darwin argues that natural selection acts on naurally-occurring, pre-existing variation. There do not need to be any new mutations in the separated populations, just changes in allele frequencies that become fixed with time and selection.

 

BINGO!!! Dave nailed it. I can't remember the exact statistic, but the majority of mutations have no effect or are deleterious. Gene mutation can be a driver, but is by far the weakest.

 

 

Darwin keg party? I'm there!

 

Cheers

Mike

[SeanCallan]

No, of course it doesn't always have to be millions of years; the quicker you can turn over your population, the more quickly those forces can act - elephants will "evolve" more slowly than bacteria, for example.

 

I think it's funny you mentioned Elephants. I was recently reading some articles about how scientist now want to declare that various Elephants are subspecies because they've observed significant differences among them.

 

I should add that evolution isn't always genotypes but can be phenotypes (Pepper Moth anyone?) which is the case with Elephants therefore significantly reducing the "evolutionary time"

 

I'll see if I can find it again.

 

phenotype: The observable traits or characteristics of an organism, for example hair color, weight, or the presence or absence of a disease. Phenotypic traits are not necessarily genetic

Edited October 10, 2008 by SeanCallan

[sen5241b]

When talking about what constitutes speciation and what precisely differentiates a species versus a sub-species we need to remember that nature does fit into our precise natural categories of order, genus, family, etc. Nature will always provide exceptions that defy any classification system of the natural world. You cannot define exactly where species mutation ends and new speciation begins.