Scientists solve fish evolution mystery

February 10, 2017
Different species of fish, called cichlids, swim in East Africa's Lake Victoria. More than 700 cichlid species have evolved in the Lake Victoria region over the past 150,000 years. Credit: Florian Moser

A University of Wyoming researcher is part of an international team that has discovered how more than 700 species of fish have evolved in East Africa's Lake Victoria region over the past 150,000 years.

Catherine Wagner, a UW assistant professor in the Department of Botany and the UW Biodiversity Institute, describes the phenomenon—unparalleled in the animal and plant world—as "one of the most spectacular examples of the evolution of modern biodiversity."

She and fellow researchers from Switzerland's University of Bern and the Swiss Federal Institute of Aquatic Science and Technology have demonstrated for the first time that the rapid evolution of Lake Victoria cichlids—brightly colored, perch-like fish—was facilitated by earlier hybridization between two distantly related cichlid species from the Upper Nile and Congo drainage systems.

The research is published today (Friday) in the journal Nature Communications. The first author on the paper, Joana Meier, is a Ph.D. student Wagner co-supervised at the University of Bern. Wagner, along with Meier's other supervisors—Laurent Excoffier and Ole Seehausen—are senior authors of the paper.

Wagner says the of the East African cichlids had puzzled researchers, who didn't understand how a single common ancestor could divide into 700 species so quickly. The discovery that the ancestor of these fish species was actually a mixture of two different ancestors from different parts of Africa makes it "much easier to understand how the immense variety of fishes in this region have evolved," she says.

"An analogy is: If you combined the pieces from two very different Lego sets—say, a tractor and an airplane—you could get a much wider variety of possible structures," Wagner says.

This modified diagram from Nature Communications shows the region of Africa and the different types of fish that have evolved from hybridization that took place about 150,000 years ago. Credit: Swiss Institute of Aquatic Science and Technology

The species that evolved exhibit many combinations of colors and are adapted to different habitats, such as sandy bottoms, rocky shores or open waters—ranging from the clear shallows to the permanent darkness of the turbid depths, according to a media release from the Swiss Federal Institute of Aquatic Science and Technology. Depending on the species, cichlids may scrape algae from rocks, feed on plankton, crack open snail shells, forage for insect larvae or prey on other fish, including their eggs or scales.

The hybridization event probably took place around 150,000 years ago, when—during a wet period—a Congolese lineage colonized the Lake Victoria region and encountered representatives of the Upper Nile lineage. Across the large lakes of this region, the hybrid population then diversified in a process known as adaptive radiation, or evolution of multiple new species adapted to different ecological niches.

While the precise course of events in ancestral Lake Victoria has yet to be reconstructed, it is clear that, after a dry period, it filled up again about 15,000 years ago. Descendants of the genetically diverse hybrid population colonized the lake and, within the evolutionarily short period of several thousand years, diverged to form at least 500 new cichlid species, with a wide variety of ecological specializations. The particular genetic diversity and adaptive capacity of Lake Victoria's cichlids is demonstrated by the fact that more than 40 other fish species—which colonized the lake at the same time—have barely changed since then.

The study involved sequencing over 3 million sites in the genome of 100 cichlid —a task which, until recently, would not have been feasible.

Wagner's study of evolutionary adaptive radiation earned her the 2015 Theodosius Dobzhansky Prize as an outstanding young evolutionary biologist from the Society for the Study of Evolution.

Wagner has published a range of papers in top-tier journals, including Nature, Nature Reviews Genetics, Evolution and Molecular Ecology. At UW, she and her lab focus on using genetic and ecological data to study the evolution of biodiversity, primarily in freshwater fish. Her research uses population genetic, genomic, phylogenetic and comparative methods to study diversification, from speciation processes to macro-evolutionary patterns of biodiversity.

Wagner received her Ph.D. from Cornell University in 2011, and she was a postdoctoral research associate at the Swiss Federal Institute of Aquatic Science and Technology before starting as an assistant professor at UW in 2015. She received her bachelor's degree in biology and geology from Whitman College.

Explore further: Study shows evolution does not always mean more diversification

More information: Joana I. Meier et al, Ancient hybridization fuels rapid cichlid fish adaptive radiations, Nature Communications (2017). DOI: 10.1038/ncomms14363

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FredJose
1.2 / 5 (18) Feb 10, 2017
Wagner says the rapid evolution of the East African cichlids had puzzled researchers, who didn't understand how a single common ancestor could divide into 700 species so quickly.


Firstly one should throw out the equivocation - speciation being mangled with the implied darwinian evolution. The cichlids are still exactly that. They haven't changed into sharks or squid or anything else.

Secondly, this phenomenon is rapid speciation, exactly as the creationists have long been telling people, given the limited supply of genome from Noah's ark. Now people discover this fact and lo and behold they want to create another senseless oxymoron - "Rapid Evolution", implying that the supposed darwinian stuff has happened.

So the bottom line is that the creationists have just been proven right once again and the evolutionists are grabbing the result which negates their religion and turning it into a support for the mythical darwinian nonsense.
Whydening Gyre
4.5 / 5 (10) Feb 10, 2017
I saw the 1 comment in the last commented list and just knew Fred was spouting his nonsense on this one...
komone
4 / 5 (4) Feb 10, 2017
given the limited supply of genome from Noah's ark. Now people discover this fact and lo and behold they want to create another senseless oxymoron - "Rapid Evolution", implying that the supposed darwinian stuff has happened.


No doubt others have observed that if you accept the reality of the effect of genetics (which you appear to do) and the logical outcome of that - you just stated a senseless oxymoron yourself?
antialias_physorg
4.4 / 5 (12) Feb 10, 2017
The cichlids are still exactly that. They haven't changed into sharks or squid or anything else.

And why would you expect them to? It seems you have a very warped 8and utterly wrong) idea of how evolution works.

given the limited supply of genome from Noah's ark.

Oh Puh-leeese. why don't you trot out the story about big bad wolf and the three piglets.
Quoting fairy tales on a science site? Really? I mean...really? How far gone do you have to be to think that that is a type of argument that is even worth typing in?

Get help. Quickly.
TrollBane
4.2 / 5 (6) Feb 11, 2017
FredJose post a total disaster. Sad. I give the best 1 star ratings ever.
Whydening Gyre
4.3 / 5 (6) Feb 11, 2017
The cichlids are still exactly that. They haven't changed into sharks or squid or anything else.

And why would you expect them to? It seems you have a very warped (and utterly wrong) idea of how evolution works.

AAP - If I could 5 ya again, I would.
given the limited supply of genome from Noah's ark.

Oh Puh-leeese. why don't you trot out the story about big bad wolf and the three piglets.

Hey, now! I really liked that story...
...
How far gone do you have to be to think that that is a type of argument that is even worth typing in?
Get help. Quickly.

Is there even any available for one so far past the tipping point?
Bart_A
1 / 5 (9) Feb 11, 2017
Scientists have not solved any of the deep "mysteries" of evolution. All they have done is observe some species in a lake that haven't been found elsewhere.

Now you scientists, can't you think deeper than just try to assign this observation to evolution? There are other possibilities. If you think hard.

Whydening Gyre
4.6 / 5 (9) Feb 11, 2017
Scientists have not solved any of the deep "mysteries" of evolution. All they have done is observe some species in a lake that haven't been found elsewhere.

There was no "deep" mystery. They just found a isolated location that gave a prime example without too many other variables to muddy the waters. Kinda like Darwin did...
Now you scientists, can't you think deeper than just try to assign this observation to evolution? There are other possibilities. If you think hard.

Evolution is a causality based (via the local environment) structure. With MANY scientists invested in ferreting out the incredible number of connections involved. Incredibly tedious and time consuming, which doesn't match the expectations of some not willing to understand that fact. Those few want answers and they want them NOW...
Maybe you'd be willing to provide just one other possibility without saying "they were CREATED that way"...
Think hard, now...
Whydening Gyre
4.3 / 5 (6) Feb 11, 2017
Here, Bart. Try this video about Misconception of Evolution -
https://www.youtu...iFG43ZZg
carbon_unit
4.3 / 5 (6) Feb 12, 2017
given the limited supply of genome from Noah's ark.
Would you care to explain how fish got to and from the ark? The ark story is full of holes when one looks at the physical and biological world.
http://www.talkor...athering
http://www.talkor...survival
Bart_A
1 / 5 (7) Feb 12, 2017
So sad that Gyre avoids any real discussion and goes on his own rants. Stay with the subject, sir! Be a man.
434a
4.2 / 5 (5) Feb 12, 2017
So sad that Gyre avoids any real discussion and goes on his own rants. Stay with the subject, sir! Be a man.


Genesis 7:12 The rain fell upon the earth for forty days and forty nights.

Ok freshwater yes, rain is fresh water. And all the species currently on planet Earth were created at the same time and their have been no new species since, yes?
So I could take a Tuna -for example- and dilute it's salt water with the equivalent fresh water that would cover the whole Earth up to the top of Mount Everest. Let's say that's 30% salt water 70% freshwater. I mean a Tuna in the North sea is in 60 meters of salt water, if it's lucky, so I think 30:70 is pretty generous. How long will my Tuna live for? An hour? A day? A week? I mean the Tuna today are exactly the same as the Tuna then correct?
cgsperling
Feb 12, 2017
This comment has been removed by a moderator.
Whydening Gyre
3.7 / 5 (3) Feb 12, 2017
So sad that Gyre avoids any real discussion and goes on his own rants. Stay with the subject, sir! Be a man.

I put forward facts and you call it a rant? I comment specifically on the subject and you say I am not on it?
Be a man, he says...
Hunh?!?
(shaking my head in disbelief...)
I say, use the brain given you., Bart... It's what a god would want you to do...
BTW, a rant would be the rage I felt for being kicked out of a religious school for asking the wrong questions...
Religious folk are bullies. And not the brightest ones, at that.
Own up to the fact that I made comment that actually made some sense and it scared you...
Be a man.
Bart_A
1 / 5 (3) Feb 13, 2017
Gyre, you may put out some unrelated facts, and at the same time completely ignore the topic at hand. It is a dodge and a chicane. You are fake.
Whydening Gyre
4 / 5 (4) Feb 13, 2017
Gyre, you may put out some unrelated facts, and at the same time completely ignore the topic at hand. It is a dodge and a chicane. You are fake.

They were completely related and on topic, put forth in response to an individual trying to derail the topic. The "topic at hand" that i choose to ignore is your version, as it is a product of your up-bringing and fear of the unknowns of reality. It evolved per someone else's direction. Just as you wish everything was done, as it relieves you of the responsibility to examine and think too critically.
IOW, your viewpoint is a construct that you cling to out of fear of - whatever...
An illusion.
Your whole life is a fake...
Bart_A
1 / 5 (4) Feb 15, 2017
Gyre, open your eyes and ears. And then maybe you'll be able to see some truth. I am done talking with you---no reason to waste any more cycles with someone who doesn't want to debate.

434a
5 / 5 (3) Feb 15, 2017
Gyre, open your eyes and ears. And then maybe you'll be able to see some truth. I am done talking with you---no reason to waste any more cycles with someone who doesn't want to debate.



I wanted a debate, I asked you a question, are you able to provide an answer?
Whydening Gyre
5 / 5 (1) Feb 18, 2017
Gyre, open your eyes and ears. And then maybe you'll be able to see some truth. I am done talking with you---no reason to waste any more cycles with someone who doesn't want to debate.

Said the pot calling the kettle black...
You're truth is so subjective, it's silly...

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