1. pharyngula
  2. Evolving fish of the lower Congo

Evolving fish of the lower Congo

By pharyngula on December 22, 2009.

The lower Congo river is deep and complex, and there are a surprising number of hydrologic features that act as barriers separating populations of fish — this very nice video explains the diversity of species and the ongoing evolution of the fish in this environment.

They too briefly showed a blind depigmented cichlid that apparently lives in very deep troughs in the river — I wanted to see more about that. It's probably out of the question to send divers down into that maelstrom, but cameras? Someday? Please?

Tags
evolution
Organisms
Science

More like this

Nat Geo Specials: And Then There Were Two
Tonight, I presume, you all are going to tune in and check out National Geographic's Morphed series. It was truly a blast to watch! But, what are your plans for this Tuesday? Because the fun's only just begun, and let me tell you, they saved the best for last. On Feb 10th starting at 9 PM, the…
Giant insect splits cavefish into distinct populations
In Mexico's Cueva del Azufre (the Sulphur Caves), a small fish called the shortfin molly (Poecilia mexicana) is on the way to becoming two separate species. Those that live in the dark interior of the caves are very different to their relatives that swim in the bright, surface waters. They have…
Evolving guppies shape their environments
The streams of Trinidad and Tobago are home to the most unexpected of landscape gardeners. They're guppies - tiny and beautifully coloured fish, just an inch or so long. Without tools or plans, they shape the environment around them, tweaking everything from the numbers of different species to the…
One gene, many fish
The Great Lakes of East Africa swarm with fish--particulary with one kind of fish known as cichlids. In Lake Victoria alone you can find over 500 species. These species come in different colors and make their living in many different ways--sucking out eyeballs of other cichlids, scraping algae off…

That looks like an interesting YouTube channel. I can see i'm going to be spending a few hours in front of my computer over the holiday.

Wow. That was so neat.

Excellent video. 500 foot deep holes in mid-river !!!

The Columbia and Snake River system in the U.S. used to have a similar type of speciation and diversification by stream reach, until it was destroyed by dams. As did the Tennessee River system (for freshwater mussels), until it was destroyed by dams.

@Douglas Watts

Dams are evil. We get it.

I can think of a few people I'd volunteer to carry a camera and a load of bricks into those holes. In the interests of science of course.

Great video. These guys get to do fantastic science and extreme kayaking for a living! So jealous.

question:

how many mutations are measured from fish to fish on the same side of the river? How many sample were taken on each side of the river to be able to determine the number of mutations of separated the two populations?

I realize they said that speciation has not occurred (as if there is some delimiting line for that), but still I dont understand how they can make the statement about how many mutations separate one population from the other.

Not a troll, genuinely wondering.

I realize they said that speciation has not occurred (as if there is some delimiting line for that),

There is a delimiting line. Different species can't breed with each other. It's the definition of what constitutes a species.

Someone with more knowledge will have to answer your other questions.

@tsg "There is a delimiting line. Different species can't breed with each other. "

It ain't necessarily so... dogs and wolves, zebras and horses. I have heard it defined as unable to produce offspring that can reproduce, but clearly Canis Lupus and Canis Domestica can do that. So I would say the line isn't clearly defined, and is essentially man-made.

But they're still just fish.

-just kidding-

Just wanted to let people know that Michael Shermer is on Larry King tonight with Deepak and Dinesh D'Souza.

By david madero (not verified) on 22 Dec 2009 #permalink

When are the cops going to take that sticking piece of garbage seriously and lock him up for his threats?

Dams are evil. We get it.

You're being rude and juvenile. Very few people are aware of the native species diversity of the Columbia/Snake and Tennessee River systems and the drastic effect on them caused by dams constructed in the 1930s and continuing today.

In the U.S. we have river resources just as unique and incredible as the Congo and many of them are in terrible condition (or flat out going extinct), which makes it impossible for a video like this to even be filmed here. This video could have been made at Celillo Falls on the Columbia in the 1920s. But in the 1930s the Bonneville Dam was built without any environmental review and destroyed all of Celillo Falls and a huge Native American sustenance salmon fishery there.

This area of the lower Congo has long been eyed for damming and still is -- precisely because of the steep gradient and rapids. If that were to happen, all of these species would go extinct.

The AMNH's documentation and research illustrates how the Congo's hydrology and ledge geography creates special, isolated niches for cichlids, and these niches are creating speciation even as we speak. Their research is important as a scientific hedge against some lame brain at the World Bank thinking that putting a dam here and wrecking the place would be a good idea.

< hrf="http://www.vp.cm">chn whlsl chp prd gcc snkrs pm trnrs.All f prdcts r tp qlty;pckng cms wth rgnl bxs.nd rgnl tgs/lbls nd th styl cd nmbr r th 100% crrct Vrs szs nd clrs r vlbl n r stck. Fshn dsgn, pplr n Erp nd Nrth AmrChrstn dgr.

By links of london (not verified) on 22 Dec 2009 #permalink

Jeez you turn off comment moderation for five minutes and all of a sudden you get psycho xians and Chinese knockoff dealers. I see what you're dealing with here PZ.

PS, who wants to bet "atheismisdead" has a tiny little winky?

@Techskeptic

The haploptype diagram shows it the best, I think...the group of green circles are the population from one side, the yellow circles are the population from the other. The larger the circle, the more specimens that share the 'same' genetic makeup. The farther each circle is away from the next, the greater the variation between them. So you can see, the difference between the two populations was much greater than the difference in each population.

As for the sample sizes, they had numbers listed in each haplotype circle...looks like under 20 from each side...(if those numbers refer to individuals sampled)

Sample size seems a little low to do more than identify gross differences...a more detailed study would need a larger population of individuals.

By Michael Osborne (not verified) on 22 Dec 2009 #permalink

I never realized spamming was this horrible here, it always really annoyed me when registration was turned on - since it disabled my posting, sigh...

Either way, as lovely as natural resources such as rivers are, we also need the resources to produce energy etc.

But I agree it's necessary to shed light on the full ramifications of building them. It's probably just one of the phases we have to grow through, like the industrial revolution. It's going to take a more advanced level of technological sophistication to bring the Earth back to a pre-human state, while still being able to live here comfortably and develop.

Ideally I think it'd be nice that one day, we can just take our entire species of this planet, terraform a nearby planet, and watch evolution on our new giant Earth-sized laboratory. (Or find yet another planet to terraform to live on, and watch abiogenesis on the other terraformed planet.)

To the future my fellow apes!

Anon: Terraform another planet? So the environmental destruction we've foisted on this planet isn't enough for you? You want to ruin another one?

;-)

Kidding aside, IMO we'd be better off building space habitats and leaving planets as we find hem.

Just look at all that lovely water ... amazing! In southern Australia we've had drought for over a decade, I'm not allowed to wash my car and my garden is mostly dead. I'd just like to have some of that water here. The whole idea of a two kilometre wide river makes my head spin!

By Janet Holmes (not verified) on 22 Dec 2009 #permalink

I'm missing a letter "t" from the last word in my previous comment.

*sigh* Preview, preview, preview.

@ MarkW

I heard that argument somewhere else, that we'd be destroying the ecology of the Moon when we'd start building / terraforming it.

I mean

Douglas Watts,

Thanks for the links - I was not aware of this appalling plan. Big dams are probably the only power sources more environmentally destructive than a coal-fired power-station.

By Knockgoats (not verified) on 23 Dec 2009 #permalink

Thanks, PZ, a fascinating film, illuminating a theme I'm interested in: that ecological complexity (high species diversity, many species interactions, wide range of specialisations) is often dependent on that of the non-living environment - consider archipelagos and alpine regions as other examples. I don't think it's always so - tropical forests look like a counter-example. Anyone happen to know the literature on this topic?

By Knockgoats (not verified) on 23 Dec 2009 #permalink

The blind depigmented cichlid is Lamprologus lethops, I believe. At what point in the video is it shown? I cannot view the video right now. At cichlidae.com there is an image of a preserved specimen housed at the AMNH.

how many mutations are measured from fish to fish on the same side of the river? How many sample were taken on each side of the river to be able to determine the number of mutations of separated the two populations?

At 6:54 in the video, you can see the comparative haplotype diagram for samples from the two banks of the same section of river; each circle represents a particular haplotype (base-pair sequence, essentially) and the number inside the circle shows how many individuals (samples) have that same haplotype.
The lines between the circles show how many base pairs difference there are between one end of the line and the other. Each small dot on a line represents one BP difference and where there are more than ten(?), a number is shown instead. You can determine the number of samples on each side by totalling the numbers in the circles.
Like the guy said, they haven't done a long enough sequence (only a few kBP so far) for conclusiveness yet, but it's a pretty good indicator of where the data seems to be going.

By randombloke (not verified) on 23 Dec 2009 #permalink

Awesome. I wonder, since the river is so deep at certain points, whether the chemistry of the water is affected by changes in lithology. This could also be helping the speciation process.

Also, the comment section goes out of topic very quickly. Maybe we need a Pharyngula forum for random chit chat.

Kg, it's certainly true (and, as I recall, a long-acknowledged tenet of community ecology) that structural complexity of the environment promotes biodiversity and ecological complexity. In tropical forests, structural complexity is ecological complexity, sort of, as the structural complexity comes from the plants of various heights and growth forms. Similarly, coral reefs have lots of structural complexity of biological origin.

By Sven DiMilo (not verified) on 23 Dec 2009 #permalink

You're being rude and juvenile.

No, I just don't care.

I'm missing a letter "t" from the last word in my previous comment.

At least you are missing any vowels...

By mmelliott01 (not verified) on 23 Dec 2009 #permalink

It ain't necessarily so... dogs and wolves, zebras and horses. I have heard it defined as unable to produce offspring that can reproduce, but clearly Canis Lupus and Canis Domestica can do that. So I would say the line isn't clearly defined, and is essentially man-made.

I'm going by definition #2 from here. Yes, there are probably exceptions, but in the context of the video this is likely what they meant.

Re: my #43

Also, from here: "The researchers therefore concluded that domestic dogs and wolves are the same species."

I saw a talk on cichlid diversity earlier this semester by another researcher out of the AMNH (props!)...as cool as the Congo blind depigmented cave cichlids are, they are part of a much bigger system that rocks all day and night (you know...for vertebrates). There have been multiple origins of that ecotype within the cichlids. In summary:
Blind depigmented cave cichlid + pop gen + Congo hydrodynamics = flava.

By Antiochus Epiphanes (not verified) on 23 Dec 2009 #permalink

Sven@40,
Thanks - that's the generalisation I was looking for - structural complexity, whether itself produced biologically or not, underlying ecological complexity. Are there any positive counterexamples to that - i.e. complex ecologies in structurally simple environments?

By Knockgoats (not verified) on 23 Dec 2009 #permalink

Dams are bad? They can't be. Virtually every significant hydro power source in the US is being exploited. Ditto Europe. It would be the height of hypocrisy for people who are outraged by an hour long power outage to tell the people of the Congo they shouldn't have electricity. I can't believe enlightened Westerners could be capable of such hypocrisy.
It might be more useful to offer some sort of alternative before condemning other people for pursuing your lifestyle. Since that area of the world is not terribly suited to solar,wind or nuclear power I'd be interested in hearing what the alternative proposals might be.

Peter G.@47,

It would be the height of hypocrisy for people who are outraged by an hour long power outage to tell the people of the Congo they shouldn't have electricity.

Yes.

I can't believe enlightened Westerners could be capable of such hypocrisy.

ROFLMAO!!

BTW, even if the people of the Congo need energy in the form of electricity, it does not follow that ecological impoverishment due to damming of their rivers can't be a bad thing. It can. And it is.

I'm Brazilian and I know first hand some of the problems it has caused there.

The so called, Enlightened Westerner's school of thought which is unfortunately also prevalent in Brazil, is IMHO, waaay over rated.

By Fred The Hun (not verified) on 23 Dec 2009 #permalink

There is a delimiting line. Different species can't breed with each other. It's the definition of what constitutes a species.

It's one out of 147 competing definitions of "species", which have nothing in common except the word "species", even though several of them describe several – different – kinds of categories.

(The number 147 was correct in February. It may no longer be.)

By David Marjanović (not verified) on 23 Dec 2009 #permalink

Fast moving streams are not the only long narrow isolating barriers. I wonder what the long-term effects of the US interstate highway system is having on speciation of small land animals like mice, voles, frogs, lizards and salamanders?

By chuckgoecke (not verified) on 23 Dec 2009 #permalink

Darwin is still right:

“Nor shall I here discuss the various definitions that have been given of the term species. No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of species.” Charles Darwin, The Origin of Species

By Antiochus Epiphanes (not verified) on 23 Dec 2009 #permalink

Peter G, what are you on about? The Congo not suited for solar?. We do solar here in the Pacific Northwest, I'm sure they can manage it there on the equator. Lots of small scale solar operations would create local jobs, teach people about technology and teach people that they can rely on each other for improvements in their lives. A big dam sounds like another boondoggle designed to enrich kleptocratic politicians and bankers.