Evolution, illustrated: Study captures one of the clearest pictures yet of evolution in vertebrates

mice
Credit: CC0 Public Domain

What do you get when you put together several tons of steel plates, hundreds of mice, a few evolutionary and molecular biologists and a tiny Nebraska town near the South Dakota border?

Would you believe one of the most complete pictures ever of ?

Led by Professor of Organismic and Evolutionary Biology and Molecular and Cellular Biology Hopi Hoekstra, a team of international researchers conducted a years-long study in which hundreds of were released into massive, custom-built outdoor enclosures to track how light- and dark-colored mice survived in light- and dark-colored habitats.

The results not only confirmed the intuition that light-colored mice survive better in light-colored habitats, and vice versa for dark-colored mice, but also allowed researchers to pinpoint a mutation related to survival, specifically that affects pigmentation, and understand exactly how the mutation produced a novel coat color. The study is described in a February 1 paper published in Science.

"This project has been many years in the making, and part of the inspiration for it came from the experimental evolution studies people have been doing for many years now using microbes in the lab," Hoekstra said. "The idea has been that you start with a particular population, genotype it, and then give it environmental challenges and watch how the population evolves over generations. Then you genotype it at the end and you can see, at the genetic level, what changes.

"We were interested in replicating that approach but doing it in vertebrates, and doing it in a natural environment," she continued. "And letting them evolve in habitats that—importantly—are open to predators, or at least visually hunting, avian predators."

To do it, then postdoctoral fellow Rowan Barrett (now a faculty at McGill University) and colleagues traveled to the tiny town of Valentine, Nebraska in order to take advantage of an important natural habitat—the Sand Hills.

As early as the 1930s, Hoekstra said, it had been observed that mice living in the sand hills—a large area of contiguous sand dunes with sandy, light-colored soil—are lighter in color than those living in the surrounding areas with dark, loamy soil.

To understand what underlies those differences, Hoekstra, Barrett and colleagues came up with an ambitious plan to build a series of eight enclosures—each 2,500-meters-square, or just over a half-acre—four on the light-colored sand hills and four on the darker soil.

They then "seeded" each enclosure with 100 mice—half trapped from the sand hills and half trapped from the surrounding dark soil—after marking each with a tiny, embedded RFID tag and taking the very tip of their tails for genetic sequencing. Three months later, researchers returned and set to identify which of the mice survived.

"The idea was to start with the maximum amount of phenotypic variation, because that would give us the most power," Hoekstra said. "For this study, we asked, of those mice we started with...which ones survived after three months of natural predation?

"So the first thing we did was to look at phenotypes, and we asked if the average color of a mouse in an enclosure changed over time" she continued. "And what was very clear was that, in the light enclosures, the average mouse became lighter and in the dark enclosures they got darker, so already we could see there had been phenotypic change."

That phenotype information, however, was only part of the story—Hoekstra and colleagues also wanted to understand whether there may be genetic differences in the surviving populations.

"We knew that coat color was heritable, and based on our previous work, we focused on one pigmentation gene that we knew contributed to the color variation in these Nebraska populations," she said. "We sequenced the entire 200,000 base pairs of that gene...and we found a handful of that were nicely correlated with survival."

The team chose to focus on one—a protein coding change that resulted in the deletion of a single amino acid from the resultant protein—which was associated with a shift toward a lighter coat color.

"That told us that mutation was associated with survival, but we wanted to know exactly what the mutation did," Hoekstra said. "We worked in collaboration with Jonathan Duke-Cohan at Harvard Medical School to do a series of biochemical analyses to show that this mutation affected the binding property of this protein in a way that leads to lighter coloration."

Further tests using gene-editing techniques, Hoekstra said, confirmed that the mutation on its own resulted in visibly lighter-colored mice.

"That was such a satisfying result—the fact that you can just look at a mouse see a difference," Hoekstra said. "You can imagine a scenario where a mutation caused a change in color, but you can only see it if you measure it with a very precise instrument, but here it was wonderfully obvious."

Going forward, Hoekstra said, there are two main paths for researchers to pursue—further investigating whether there may be other genetic differences, in pigment genes or other genes, that help mice exist either on or off the sand hills, and the other investigating change over multiple generations.

"Yes, there is a big difference between the soil color on and off the sand hills," she said. "But they also differ in vegetation and other ecological aspects, so there are likely other differences besides color at the phenotype level that we'd like to tap into as well. In that case, looking genome wide and asking if there are other regions of the genome that affect fitness will be a next step as well as looking across generations."

Ultimately, though, Hoekstra said the study offers an important—and importantly complete—picture of how evolution works in mammals.

"What I like about this study is it starts at the organismal level and goes all the way down to a mutation, and understanding how, precisely, that mutation leads to a change in phenotype and how that change leads to survival differences in the wild," she said. "So I think this is a very satisfying illustration of the full process of evolution, from the ecological consequences of these phenotype changes down the molecular details."


Explore further

Mice living in sandy hills quickly evolved lighter coloration

More information: "Linking a mutation to survival in wild mice" Science (2019). science.sciencemag.org/cgi/doi … 1126/science.aav3824
Journal information: Science

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Citation: Evolution, illustrated: Study captures one of the clearest pictures yet of evolution in vertebrates (2019, January 31) retrieved 20 August 2019 from https://phys.org/news/2019-01-evolution-captures-clearest-pictures-vertebrates.html
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Jan 31, 2019
Not the first time evolution has been documented on human time scales.
"Peter and Rosemary Grant have seen evolution happen over the course of just two years."
https://www.pbs.o...op1.html

Jan 31, 2019
Mutations are basically errors slipping into the genetic code. It is a downgrade, not an upgrade. Evolution states that we are the result of upgrades. That has never been observed. Calling these mutations evolution is preposterous. It is rather called confusion.

Jan 31, 2019
While you are correct that mutations are the result of errors in the genetic code (this is the raw material of evolution), it is incorrect to say that evolution is the result of upgrades; evolution is directionless. All that matters is survival; whether it's due to addition or deletion of genetic code is irrelevant.

Feb 01, 2019
"So I think this is a very satisfying illustration of the full process of evolution, from the ecological consequences of these phenotype changes down the molecular details."

So if this is the full process then are the mice still mice or have they changed into some new creature with wonderfully different appearance, form and way of function?
If they are still mice then is this not an example of adaptation only?

So far there is no visible observation of darwinian evolution wherein one kind of organism changes into another kind of organism over many generations.
Anyone who says otherwise is simply kidding him/herself. Just as people are doing in this research - equivocating by using the word evolution when adaptation is being observed but fully implying that darwinian evolution is in action.

Darwinian evolution is true if and only if abiogenesis is true. Why? Because they both need purely materialistic processes to create ABSTRACT entities like Information and logic.

Feb 01, 2019
Breeding is human selection. Evolution is natural selection.

That's all there is to it.

Feb 01, 2019
Yes, "a very satisfying illustration of the full process of evolution" indeed.

And we have the obligatory non-scientists' opinion in error and against the finds:

Evolution states that we are the result of upgrades.

Darwinian evolution is true if and only if abiogenesis is true.


What in the expert description "illustration of the full process of evolution" is unclear? Evolution is variation in the population genome over generations. Mechanisms adding variation are mutation (illustrated here), recombination and migration, subtracting variation are drift, selection (illustrated here) and inbreeding.

Speciation and evolution from geochemistry can happen - and observably has happened - since there are no magical, arbitrary barriers such as you claim, without giving references.

Speciation as a consequence of evolution: https://en.wikipe...eciation .
Abiogenesis as a consequence of evolution: https://www.natur...l2016116

Feb 01, 2019
More here: https://www.theat.../581521/

"Team member Stefan Laurent sequenced a gene called Agouti, which has been linked to fur color, in all 481 of the mice. He found seven mutations that had become more common in the light enclosures, and rarer in the dark ones.

One, known as delta-Ser, seemed to have an especially strong effect. And when another team member, Ricardo Mallarino, engineered that mutation into the Agouti genes of normal lab mice, the rodents grew up with noticeably lighter coats."

A note on "magical barrier" comments: it is like claiming that falling bodies cannot drop to the ground because they can just drop 'so far'. Not what we expect, not what we see, not that the science theory predicts, not that we *know* happen..

Feb 01, 2019
geewhiz freddy. I'm squinting as hard as I can. In all directions. & no where do I see divinity fudging creation.

Guess that means, by your rules, that I needn't believe in it?

Now, you are going to claim that your funhouse mirror vision of god must exist because the universe exists?

Is that nut, uh not the same argument for the existence of Dark Matter? That we can observe it's effect?
So DM & god are two different views of the same phenomena?

However would not explaining an active deity on the observable effect of their creativity result in that deity being charged with incompetency & poor judgement?

Which brings us to ny brilliant concept of the Theory of Stupid Design? That Reality, the Universe, is a stochastic process.
That, or the goddess trickster coyote is fucking with us?

Feb 01, 2019
Again, this is not a demonstration of "evolution".
"Evolution" is the arising of new species from mutations that provide survival advantage. That's why Darwin's book is entitled "The Origin of Species". He considered the development of new species to be a fundamental part of "evolution". These animals can still breed with each other. They are of the same species.
But various aspects argue against "evolution". Among other things, that mutations are necessarily very small and don't necessarily provide any survival advantage at all. They can easily by lost from a population before they even spread. Too, any creature that is a new species will also be different from their own parents and siblings. Who, then, would they mate with to produce a colony?
The fact is that "scientists" are getting embarrassed about the fact that speciation is not occurring, so they are "defining" this as a form of "speciation" and proclaiming whenever it occurs.

Feb 02, 2019
These animals can still breed with each other. They are of the same species.


So what?

Paradox of the heap. Take a pot of water and add one centigrade of heat. Nothing happens. Add another, nothing remarkable happens. Therefore, a pot of water can never boil even as you keep adding heat?

The fact is that "scientists" are getting embarrassed about the fact that speciation is not occurring


You forget that many animals that are considered different species can in fact interbreed - they simply do not because they're separated by their niches and sexual selection. The biological compatibility is only lost after the populations have been living separately for a very long time.

Feb 02, 2019
Among other things, that mutations are necessarily very small and don't necessarily provide any survival advantage at all.


If an animal can mutate a little, it can mutate a lot. If there is a possible pathway through small incremental changes from phenotype A to phenotype B, and there is an environmental pressure to that direction, it is rather inevitable that it happens. It's like watching a round stone roll down a hill - nothing surprising or requiring any explaination.

They can easily by lost from a population before they even spread. Too, any creature that is a new species will also be different from their own parents and siblings. Who, then, would they mate with to produce a colony?


New species aren't formed from individuals, but from groups that are separated. The animal itself does not spontaneously form new species, the environment separates groups which become separate species by adapting to differences in their environments.

Feb 02, 2019
Animals living in different environments, like the mice living on dark/light soil, are being environmentally segregated because they face survival disadvantages if they venture onto each others' territories. They stop interbreeding.

In this condition, there's less genetic information exchange between the populations, so the accumulating mutations take them in different directions. The key point is that the animal is never going to remain the same - it's always changing randomly. Even if the environment remains the same, survival competition within the species makes the phenotype shift in some direction. I.e why peacocks grow fancy tails.

With little mixing between, the populations change in different directions, and eventually they become so distinct you can't tell them to be the same animal originally, except by genetic analysis and comparison. It would be more difficult to come up with a reason why they wouldn't turn into different species.

Feb 02, 2019
Evolution is a description pf what we have observed.
People take that data & make inferences based on their body of knowledge & what they choose to believe is it's meaning.

Darwin, was one of many pioneers of the biological sciences.
His name is now used as political slogan for those that deny evolution,
No thinking needed, just keep repeating the mantra.

Charles Darwin was a man of his time & society. Quoting him out of context?
Exposes your ignorance of his life & British history. He was immersed in the Culture of his Caste.

An astronomer of his time, say Carrington or Hodgson. Worked with limited, what we would consider primitive instruments. Based upon a limited body of observations & speculations.

With the continuous development of all our technology? We collect information beyond the wildest dreams of either Carrington or Hodgson. That does not take away from their accomplishments.

"We stand on their shoulders"
"We stand on Darwin's shoulders"

Feb 03, 2019
Mutations are basically errors slipping into the genetic code. It is a downgrade, not an upgrade. Evolution states that we are the result of upgrades. That has never been observed. Calling these mutations evolution is preposterous. It is rather called confusion.

They're not downgrades or upgrades, they're changes.
Natural selection determines if they are fails or successes.
It's the mechanism of evolving, like it or not.

Feb 03, 2019
Again, this is not a demonstration of "evolution".
"Evolution" is the arising of new species from mutations that provide survival advantage. That's why Darwin's book is entitled "The Origin of Species". He considered the development of new species to be a fundamental part of "evolution".

You need to change your view of "evolution" as a noun to a verb.
But various aspects argue against "evolution". Among other things, that mutations are necessarily very small and don't necessarily provide any survival advantage at all.

They are incremental changes and thousands to millions of them may well produce a new species. Or, guess what? It may not...
...
The fact is that "scientists" are getting embarrassed about the fact that speciation is not occurring, so they are "defining" this as a form of "speciation" and proclaiming whenever it occurs.

They're not embarrassed, cuz no scientist is doing that.
Please show me if they are.

Feb 03, 2019
Nice simple question: would you agree lions and tigers are separate species?

Feb 03, 2019
Betcha none of them has the balls to answer.

Feb 03, 2019
Here's why:

Lions have tufts on their tails. tigers have none. Ligers often, but not always, have tufts.
Lions have manes; ligers have none.
The liger is the largest felinoid; ligers have been measured at over 1,000 lbs. The largest lions are ca. 900 lbs; the largest tigers ditto.
Ligers have stripes; lions have none.
Ligers swim like tigers; lions do not swim.

And this is not a mule; there are both male and female ligers, and they are not sterile. They breed more ligers.

Now, again, are lions and tigers separate species?

Feb 03, 2019
Ligers associate in prides; they're far more social than tigers. Tigers are loners, both male and female.

Shall I go on or do the anti-Darwin YEC cretinists care to show up on a level playing field where they can't bring moderator power to support them?

If they don't show up they're cowards admitting they lie for jebus.

Feb 03, 2019
Da Schneib: even simpler. Consider dogs:
http://cdn.skim.g...eed-dogs

The reason why we consider these two the same species is because we know they're both coming from the same animals. In reality, these two cannot interbreed as tab A is just physically too big for slot B, and even artificially inseminated the mother or child would die in a great majority of pairings.

If a naive observer came along, they would judge them to be different species exactly because they can't make babies together. It's like comparing a house cat to a panther, or a porpoise to a blue whale.

Give it another 50,000 years and they won't even look alike.

Feb 03, 2019
The irony is that animal husbandry and selective breeding is able to produce a crazy variety of different phenotypes in a hurry by applying selection pressure, but this is somehow not accepted as an example of evolution because a mouse can't suddenly sprout wings.


Feb 03, 2019
I was thinking St. Bernards and Chihuahuas but that'll do.

Feb 03, 2019
I was thinking St. Bernards and Chihuahuas but that'll do.


Another example is wolves and dogs. Genetic analysis shows that modern wolves are different from ancestral wolves, and the direct ancestor between wolves and dogs has gone extinct, which completes the species split between wolves and dogs. They're no longer sisters, but cousins in the evolutionary family tree.

Clearly evolution produces species, but this is resisted by changing the goalposts and re-defining it as "microevolution" - again on the argument that a dog won't suddenly sprout a third eye or some other novel feature, which somehow disqualifies it as being a new species.

Of course it won't. It doesn't need the novel feature, so one can't evolve.

Feb 03, 2019
" illustration of the full process of evolution, from the ecological consequences of these phenotype changes down the molecular details."

So if this is the full process then are the mice still mice or have they changed into some new creature with wonderfully different appearance, form and way of function?
FredJose

Straw man: Obviously, the "full process" they are referring to here in this context does NOT include species change.

If they are still mice then is this not an example of adaptation only?

adaptation via natural selection = evolution

Darwinian evolution is true if and only if abiogenesis is true.

FALSE. Even if the first life was made by god/gods, there is NO contradiction in that life then evolving.
Obviously, I personally don't have the STUPID superstitious belief that a god or some gods did it, but, because of what I just asserted above, that's completely besides the point.


Feb 03, 2019
FALSE. Even if the first life was made by a god/gods, there is NO contradiction in that life then evolving.


That would be planned evolution then (i.e. inevitable and determined, not evolution), because an omniscient and omnipotent creator god can't be not responsible for anything that happens. They knew exactly how it's going to turn out before they created it, and chose to create it that way anyhow.

Paradox of evil and all that. In the creation of God, there cannot be such thing as random mutation.

Feb 03, 2019
My favorite example of ongoing evolution are Reindeer. (so I'm a sentimental sap quarterFinn - cue Sibelius)

There is no physical difference, that I know of, between wild & domesticated Reindeer.

The singular, subtle difference is that domesticated Reindeer will tolerate being handled & directed by Humans.

Another interesting evolutionary shift in brain functions? Is that dogs, bred & trained for herding functions, understand long-distance signals from their drovers. Such as sharp calls, shrill whistles & hand-arm waving.

Most people today who own herding breeds, haven't a clue about the competency of their house-pet.
The ability is there, the animal need to be trained to respond.
But so do the vapid owners!

Feb 03, 2019
There are many characteristics that are more properly referred to as changes to the pre-programmed, and changeable epigenetic characteristics. But, this one seems to be correctly attributed to a genetic mutation.

Still I think this is more properly called devolution. It did not create new genetic information, and instead, something broke. This type of "evolution" is decay, not really the creation of new information. So, it is actually a very good example of how natural things change in the real world. Things decay. They don't advance. I takes intelligence to really create.

Feb 04, 2019
Still I think this is more properly called devolution. It did not create new genetic information, ....
Cadcoke5

Often False. A mutation can consist of an extra copy of a gene first being made, and then, and perhaps much later on, that extra copy mutates to take on a new function while the old gene that it was a copy of remains thus now there is an extra functional gene that wasn't there before and has a new function that wasn't taken up by a gene before.

Also, sometimes some previous junk DNA mutates to then have some new useful function.

Feb 04, 2019
Still I think this is more properly called devolution. It did not create new genetic information


Information is different from data. Having a gene deleted is "new information", because the sequence now carries a novel meaning.

This is just the "progress/regress" confusion all over. What is better or worse depends on the environment, and what is or isn't information depends on the interpreter. Data can be removed, but information can be added at the same time.

Feb 04, 2019
uhh cad my boy. Using your claim of "deevolution"?

The Homo Sap male XY chromosomes are defective versions of the female XX chromosomes.

Which hypotheses of male inferiority to females? Was recently confirmed by analysis of the genetic defects found in Humans to most often be traced to defective genetic material contributed by the male parent.

https://medicalxp...erm.html

There cad, was that the affirmation you were seeking?

Feb 04, 2019
Oy.

Again, this is not a demonstration of "evolution".


Again, what in the expert description "illustration of the full process of evolution" is unclear? I already described what the observed process of evolution entails and what scientists study: variation of a population's genome. Are you really reading articles and comments!?

Moreover, you make claims without evidence. Those can be rejected without evidence, without even knowing - as you do not, but thanks for making it so obvious for everyone - what evolution is.

The fact is that "scientists" are getting embarrassed about the fact that speciation is not occurring.


Of course we have seen it, it is evident in phylogenetic trees where we have seen it millions of times [ http://www.onezoom.org/], and we have even seen it in our lifetimes many times [ http://www.talkor...ml#part5 ].

- tbctd-

Feb 04, 2019
- ctd -

And while I am just a bioinformatician I would be in dire straits if this did not happen, since what I work with is based on evolution and divergences up to and including species divergences. I can easily see and test divergences in genes between species in a few minutes with open data bases and software - why can't you?

It did not create new genetic information


Don't bother, this is irrelevant to evolutionary methods, since we are observing what happens and not speculating against evidence,

[Though of course it has long since been tested that mutation increase Kolmogorov information and selection channel Shannon information from the environment into the genome. I don't have references handy since it is not useful, but I can look them up if anyone is interested and really know or want to know what various kinds of sequence information are.

Where else would the gene sequence information come from, do you think it has been 'put' there by *magic*!?]

Feb 04, 2019
So if you think that mutation and selection (and the other similar evolutionary mechanisms that increase
and decrease variation) should compete in both an evolutionary sense and in an information sense: they do.

In as much as variation is information, mutation (and recombination and gene flow) increase it, and selection (and drift and inbreeding) decrease it. In as much as random, stochastic Kolmogorov information is interesting, mutation - and in a a larger sense entropy - increase it. And in as much as meaningful, "message" channeling Shannon information is interesting, selection increase it and at the same time pare down the sequence Kolmogorov information. This is Information theory/Statistical thermodynamics 101.

But it is not evolution as such, we are only interested in the actual variation and what it does (means). Kolmogorov information cannot be readily calculated and Shannon information has a degeneracy regarding what the "messages" (trait variation) are.

Feb 05, 2019
This is Information theory/Statistical thermodynamics
torbjorn_b_g_larsson

No, contrary to much of the very loud weird insane rhetorics from the more fanatical anti-science fundamental theists, in science, evolution theory has nothing to do with the theory of thermodynamics. Please don't reinforce their delusions; their usual wild crazed delusions are stubborn enough as they are, thanks.

Feb 05, 2019
torbjorn_b_g_larsson

Oh sorry, I thought you were saying evolution theory is to do with the theory of thermodynamics. But now, reading your post again, I think you imply it is NOT so? If so, my apologies. Pity I cannot delete my previous posts. I think they should provide an option for that.

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