Evolution may take giant leaps

Dec 11, 2009 by Lin Edwards weblog
The Tree Of Life based on completely sequenced genomes. Image: Wikimedia Commons

(PhysOrg.com) -- A new study of thousands of species of plants and animals suggests new species may arise from rare events instead of through an accumulation of small changes made in response to changes in the environment.

The traditionally accepted idea of species evolving through gradual changes is the Red Queen hypothesis, named after a character in Alice in Wonderland, who explains to Alice that "it takes all the running you can do, to keep in the same place." The hypothesis, that species continually change and adapt to compete with co-evolving species and retain their ecological niche, was proposed in 1973 by Leigh Van Valen.

The new research, carried out by Mark Pagel and colleagues at the University of Reading, in England, studied 101 groups of plant and animal species and analyzed the lengths of branches in the evolutionary trees of thousands of species within these groups. The lengths of the branches are a measure of the time elapsed between two species branching off.

The researchers then compared four models of speciation to determine which best accounted for the rate of speciation actually found. The Red Queen hypothesis, of species arising as a result of an accumulation of small changes, fitted only eight percent of the evolutionary trees. A model in which species arise from single rare events fitted eighty percent of the trees.

Dr Pagel said that the research shows speciation is the result of rare events in the environment, such as , a shift in , or a mountain range rising up. Over the long term new species are formed at a constant rate, rather than the variable rate Pagel's team expected, but the constant rates are different for different groups of species.

The work suggests that may not be the cause of speciation, which Pagel said "really goes against the grain" for scientists who have a Darwinian view of evolution. The model that provided the best fit for the data is surprisingly incompatible with the idea that speciation is a result of many small small events, Pagel said.

The paper is published in the journal Nature.

More information: Venditti, C., Meade, A. & Pagel, M. Nature advance online publication (2009); doi:10.1038/nature08630

© 2009 PhysOrg.com

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Yellowdart
1.6 / 5 (8) Dec 11, 2009
I'd be willing to argue that since evolution occurs at reproduction, it is independent of clocks, small change accumulation, or large jumps.
It is squarely dependent upon a species own DNA and its limitations there in to adapt and evolve under considerable new environment or food source conditions.
marjon
1.3 / 5 (8) Dec 11, 2009
I can understand that a hybrid like a mule could develop into its own species.
But the same genetic mutation would have to occur in both males and females of an old species to propagate the new species.
How would rapid, random geological events trigger such broad mutation?
A virus seems like the most likely cause of such a broad based genetic event.
Pogsquog
3.7 / 5 (3) Dec 11, 2009
For a species to split, there must be a large enough difference between individuals for them to no longer be able to breed.
This can only occur when there is either factor isolating members of the original species, into distinct 'islands', or the environment changes such that there are two 'basins of opportunity' (conflicting strategies).
In the later case, the species will only split if the basins are inherently incompatible, and the members of the species are isolated enough that they can locally pursue both strategies, sufficiently that they have differentiated enough that they can no longer interbreed.
Logically, species that have larger ranges, and frequently breed further away from where they were themselves were born, will split less readily than species which breed close to where they were born. Generalists will split less readily than specialists, as they are already fit in most environments (no specialisation is required).
moj85
5 / 5 (5) Dec 11, 2009
I'm not sure I understand where the authors say that natural selection would no longer be part of speciation events. If there was a large change in climate, genetic mutation, or whatever you want, and that provided a certain subgroup of a species to flourish and pass on its own genes, wouldnt that still be considered natural selection?
nanotech_republika_pl
5 / 5 (5) Dec 11, 2009
Why is this a problem? There always be some external pushes on the living creatures making some species to die out. The author of the paper is just saying that most of the changes in DNA are due to large pushes not small ones. But it is still natural selection. That's how I read it.

I think that there is always very slow genetic drift at all times. But those big pushes (cataclysms) are able to select many species at once that just happen to be best adapted at that time. Rather than slowly trimming specie by specie as environment changes or even if it does not change.
degojoey
4 / 5 (2) Dec 11, 2009
Its not hard for DNA to alter itself, viruses do it, cosmic rays, etc... so in a new environment its not hard to imagine your DNA would be altered as you live to suit your environment. This process will take many generations but in the grand scheme if it all its only a couple thousand years for abrupt mutations to occur, which is fast. I think it has to do on how much your environment has changed from your needs and how well you and your DNA can adapt to proliferate in your current environment.
joekid
2 / 5 (4) Dec 11, 2009
I don't know much about evolution. But I have a suggestion that my help scientist find what they need to know as opposed to what their looking for. Many divisions of science study take the all or nothing approach to their fields. As archeologist, and geologist found catastrophe theory doesn't work alone to answer the questions they were asking,but still they stayed with it and learned nothing.
Evolution has many avenues it takes in the process of change and improvement of a species. So times the simplest asked(questions)are right: What happened. Case in point when I was twelve years old I saw a science show that was discussing galaxy formation. Black holes were a topic I saw the week before. I don't know if this theoretical entity was looked on as a connection but it I saw that if a large mass as a BH did exist it was the cause of galaxy formation. I may be smart but the emotional problems I had at the time dumb-ed me down substantially. I wasn't weighed down with what had tobe dogma
Szkeptik
5 / 5 (5) Dec 11, 2009
"The work suggests that natural selection may not be the cause of speciation, which Pagel said "really goes against the grain" for scientists who have a Darwinian view of evolution"

How is speciation by adopting to modified environmental factors not natural selection? Those that are better suited to survive in the new environment have higher rates of successful reproduction.
marjon
1.4 / 5 (11) Dec 11, 2009
How does the first male 'new species' find the first female 'new species'?
joekid
1 / 5 (2) Dec 11, 2009
to answer the last comment. change patterns deal with groups and if you read the bible where goats are being gathered be Jacob for what he wants stripes or spots. all you need is one male (in this instance) and a lot of females to telegraph his characteristics into the gene pool.
marjon
1.5 / 5 (8) Dec 11, 2009
to answer the last comment. change patterns deal with groups and if you read the bible where goats are being gathered be Jacob for what he wants stripes or spots. all you need is one male (in this instance) and a lot of females to telegraph his characteristics into the gene pool.


But they still have to be the same 'new species'. It has to start with one.
That is how dog and cattle breeds are started, with incest.
Donutz
1.3 / 5 (3) Dec 11, 2009
the same genetic mutation would have to occur in both males and females of an old species to propagate the new species.
How would rapid, random geological events trigger such broad mutation?
A virus seems like the most likely cause of such a broad based genetic event.

A reasonable question. Consider this: what if a mutation arose such that some or all of a given individual's children came out with, say, extra arms or something. The individual would be capable of breeding, might even reasonably be attractive to the opposite sex, but would produce one monster after the other. These offspring, likely shunned by their brethren, would interbreed, thus reinforcing the speciation within a generation.

I'm not saying this *is* what happened, but this or some variation *could* happen.
Gammagirl
5 / 5 (3) Dec 11, 2009
Isn't this punctuated equilibrium postulated by Eldredge and Gould?
Simonsez
3 / 5 (2) Dec 11, 2009
I think epigenetics could also factor in a great deal here. Consider that an ecological incident, major change in diet or other system shock, exposure to certain elements or as marjon suggested, even a virus could lead to a substantial group of a species to suddenly have similar mutation. This group could then be isolated geographically, sexually or shunned and as others have said, lead to inbreeding. Whether this leads to a new species or just a new breed of the species would depend on the degree of mutation and how synchronized it is among the group, but it seems feasible to me that epigenetic change might explain many species' existence today.
alanmatlock
5 / 5 (1) Dec 11, 2009
Natural Selection - The Red Queen Hypothesis - is extremely gradual change.
Anagenesis is basically invisible because differentiation is so gradual. This fits 8% of the data. For 85% of the data we do not see this slow change. We see rapid anagenesis. I always suspected we did not see enough transitional species to make anagenesis work with The Red Queen Hypothesis. My question is, what do the other 7% of species fit? Does anyone know?
flaredone
1 / 5 (1) Dec 12, 2009
It's well known, human society is evolving "in circles", too. Many human inventions (Antikythera machine and gear mechanism), theories (plenum or aether theory) or social arrangement (the constitution and voting systems) were forgotten and reinvented and subsequentially abandoned later again. We can see it as an analogy with spreading of energy in particle system, for example in ripples at water surface, which transforms gradually from longitudinal (Brownian noise) into transversal (capillary) waves and back into longitudinal (gravity) waves again.
flaredone
not rated yet Dec 12, 2009
Natural Selection - The Red Queen Hypothesis - is extremely gradual change.
IMO you're mixing gradualistic and running evolution concepts. Red Queen Hypothesis doesn't require gradualism, especially when natural conditions are changing fast (impact of asteroide, global volcanic activity) - compare the theory of punctuated equilibrium.

During these events the reservoir of sleeping genes in junk DNA can be involved and population of organisms would change fast into new species, while the rest (which doesn't contain such sleeping genes) dies. I particularly like this explanation, because it explains the purpose of junk DNA, but there exists another theories, for example frozen plasticity theory, derived from selfish gene theory.
marjon
1 / 5 (5) Dec 12, 2009
Natural Selection - The Red Queen Hypothesis - is extremely gradual change.
IMO you're mixing gradualistic and running evolution concepts. Red Queen Hypothesis doesn't require gradualism, especially when natural conditions are changing fast (impact of asteroide, global volcanic activity) - compare the theory of punctuated equilibrium.

During these events the reservoir of sleeping genes in junk DNA can be involved and population of organisms would change fast into new species, while the rest (which doesn't contain such sleeping genes) dies. I particularly like this explanation, because it explains the purpose of junk DNA, but there exists another theories, for example frozen plasticity theory, derived from selfish gene theory.

How does the 'junk' DNA for both a male and female 'turn on' in the same way at the same time and how do they find each other to reproduce a new species?
flaredone
1 / 5 (1) Dec 12, 2009
How does the 'junk' DNA for both a male and female 'turn on' in the same way at the same time and how do they find each other to reproduce a new species?
The basic point is, "junk" DNA is not junk at all, but it doesn't serve for production of proteins, but various RNAs, which are serving both like enhancers or suppressors of transcription of proximal genes, which are used by immune system for production of antibodies). This is particularly because fylogenetic evolution is too slow to acomodate changes in life environment, represented by various infections and parasites. I presume, at the very beginning of organic life, most of genetic variability was represented by RNA, DNA is more advanced / later stuff. This flexibility can explain Lamarckian offspring of fast adaptation to large infections or environmental catastrophes. Because these events can repeat, we can find many traits of cyclic evolution in repetetive character of many genes observed in "junk" DNA.
marjon
1 / 5 (6) Dec 12, 2009
The basic point is, "junk" DNA is not junk at all, but it doesn't serve for production of proteins, but various RNAs, which are serving both like enhancers or suppressors of transcription of proximal genes, which are used by immune system for production of antibodies). This is particularly because fylogenetic evolution is too slow to acomodate changes in life environment, represented by various infections and parasites. I presume, at the very beginning of organic life, most of genetic variability was represented by RNA, DNA is more advanced / later stuff. This flexibility can explain Lamarckian offspring of fast adaptation to large infections or environmental catastrophes. Because these events can repeat, we can find many traits of cyclic evolution in repetetive character of many genes observed in "junk" DNA.

Thanks, but my original question remains unanswered.
flaredone
not rated yet Dec 12, 2009
Thanks, but my original question remains unanswered.
The question could be, why males and females should differ in their speed of adaptation, if they've same genes (they're engendering in 1:1 ratio)? You can switch the male to female (and vice-versa) during prenatal development just by adding of hormones.

For example, we killed many wildly living species by waste waters containing hormones from contraceptive pills, which are switching male fishes to females. I'm afraid, we can observe the same effect by lost of fertility (and lost of their maleness) for men in human population.
marjon
1 / 5 (5) Dec 12, 2009
Thanks, but my original question remains unanswered.
The question could be, why males and females should differ in their speed of adaptation, if they've same genes (they're engendering in 1:1 ratio)? You can switch the male to female (and vice-versa) during prenatal development just by adding of hormones.

For example, we killed many wildly living species by waste waters containing hormones from contraceptive pills, which are switching male fishes to females. I'm afraid, we can observe the same effect by lost of fertility (and lost of their maleness) for men in human population.

The original question remains unanswered. How do the first male and the first female of a new species find each other and start the new species?
flaredone
not rated yet Dec 12, 2009
I see, now I can understand your "problem". Well, they probably would form more close social group. Recently speciation was observed for Darwin's finches. You shouldn't imagine formation of sexes like some immediate process, so your question has no meaning. Many protozoa can breed both with division like bacteria, both by mating (conjugation). In unfavourable life conditions they prefer mating, because it enables them to mutate and evolve faster. You can imagine, protozoa able to conjugate are much more "sexier" under these circumstances - so they prevail in population fast.

On the other hand, animals in stable life environment tends to parthenogenesis and they becoming cancer resistant (sharks). Even civilization diseases like endometriosis of women and the feminity of modern males could be considered as an evolutionary return to parthenogenesis as a response to favourable life conditions, because it prohibits mutations, leading to cancer.
marjon
1 / 5 (6) Dec 12, 2009
You shouldn't imagine formation of sexes like some immediate process, so your question has no meaning.


Are there not species that have sexes?

Instead of answering the question you dismiss it?

Why not just say you don't know?
Ronan
not rated yet Dec 12, 2009
Marjon, I think the issue lies with how you imagine a new species forming. It's not a sudden process for ANY model of evolution; no one's ever argued for, say, a theropod laying an egg that, *poof*, hatches into a fully-fledged (literally, I suppose) archaeopteryx. Even with "sudden" evolution as proposed by this paper, the process would take many generations, and at no single step along the chain would a new species just pop into being. You'd have one creature mating with another that, although decidedly weird, would still be within the range of variability for that species. Then, assuming the fastest possible evolution, their offspring would carry variations on that weirdness that would help them survive, and those who carried the "weird" gene (while still not being another species) would end up siring the most offspring, some of which (by chance) might compound the original weirdness with another out-of-the-common-way trait.
Ronan
not rated yet Dec 12, 2009
If that, too, were successful, then it also would spread throughout the population over several generations, and then if some member of the population developed some further weirdness that was helpful...well, you get the idea. Of course, you'd also get quirks and oddities showing up that WEREN'T helpful, but they'd be selected against, and would disappear pretty quickly. At no stage do you have creatures mating with some other animal that isn't a member of their own species, but in a few tens or hundreds of generations, one species has turned into another, nonetheless.
Ronan
not rated yet Dec 12, 2009
(Sorry for the run-on multiple posts)
Note this paragraph in the paper, by the by. "Dr Pagel said that the research shows speciation is the result of rare events in the environment, such as genetic mutations, a shift in climate, or a mountain range rising up. Over the long term new species are formed at a constant rate, rather than the variable rate Pagel's team expected, but the constant rates are different for different groups of species." They're not just saying that these sudden leaps in evolution would be initiated by genetic mutations. Something as slow as the rising of a mountain chain qualifies, in this case, as a "sudden" alteration, when compared to the slow 'n steady gradualistic change that was expected. The researchers are simply arguing that evolution is driven by dramatic changes, not by a Red Queen "Keeping up with the Joneses" model. Of course, if the Joneses suddenly acquire the biological equivalent of a thermonuclear warhead, that counts as a sudden change...
superhuman
not rated yet Dec 12, 2009
How does the first male 'new species' find the first female 'new species'?

The process is not sudden and takes many mutations over many generations.

For example a certain species covering a large area is under pressure present only in one particular location. For example it is attacked by a deadly parasite which only lives there due to climate. At some point one individual acquires mutation making him more resistant to the parasite - he can still breed with the rest of his species and he passes this mutation to his offspring giving them an advantage.

Many generations later another mutation happens in one of his descendants which gives him and his offspring immunity from the parasite but at a cost of not being able to mate with individuals who do not have the first mutation, by now however most in the area infested by the parasite will have the original mutation due to natural selection and so he will be able to find mates and will give rise to subspecies.
superhuman
not rated yet Dec 12, 2009
The example above is of course simplified for the purpose of clarity.

In more general terms species which are spread over a large area will naturally divide into groups usually defined by geography. Individuals in such groups are more likely to breed withing the group then with more distant relatives. Each group will also likely face different selection pressures.

Beneficial mutations that will easily spread within one particular group may not make it into others especially if those mutations are neutral or detrimental in conditions facing those other groups.

Eventually enough changes will accumulate between distant groups to make them unable to interbreed leading to speciation.
Nik_2213
5 / 5 (1) Dec 12, 2009
IIRC, the situation described in the article is known as 'Founder Effect'. Isolated, a small group (genetically speaking) may evolve independently of main population. Random, often recessive variations in their original mix get a chance to back-cross and emerge. Nothing new or contentious, there...
flaredone
not rated yet Dec 13, 2009
..speciation is the result of rare events in the environment, such as genetic mutations...
Maybe yes, but the example of speciation of Darwin's finches demonstrates, the formation of new species could be pretty gradualistic process. Why to develop new mechanisms for evolution, when we can observe it in real situation?

http://news.natio...ion.html

The same process we can expect at the case of sexual reproduction: some bacteria developed the ability to conjugate accidentally, but they didn't use it for anything in the same way, like birds don't use their colours for nothing special. Just after some catastrophe (I presume, it was Snowball period during Cambrian explosion) forced them to use conjugation more often, because such way of breeding increases mutation and speciation rate, which turned to be advantageous in this situation.
Nyloc
not rated yet Dec 13, 2009
I think that the operant condition here may be the relatively large influence mutations have under the conditions of reduced population.

Dramatic changes may draw down population due to the struggle to adapt to new circumstances. Under such conditions, mutations which offer a favorable advantage can have a magnified effect on a smaller gene pool through mathematical distribution.

Case in point ... it has been suggested that the human population when through an early 'bottleneck' when may have increased the pressure to adapt, thereby amplifying advantageous traits.

Dramatic events may accelerate the evolutionary process. Tragedy has it's benefits.
Mercury_01
1 / 5 (3) Dec 14, 2009
It's well known, human society is evolving "in circles", too. Many human inventions (Antikythera machine and gear mechanism), theories (plenum or aether theory) or social arrangement (the constitution and voting systems) were forgotten and reinvented and subsequentially abandoned later again. We can see it as an analogy with spreading of energy in particle system, for example in ripples at water surface, which transforms gradually from longitudinal (Brownian noise) into transversal (capillary) waves and back into longitudinal (gravity) waves again.


I think what you're (painfully) getting at is that DNA is subject to nonlocal influence, and that it's information exists at large, to be expressed as conditions allow. If so, then I agree.
BobSage
1 / 5 (5) Dec 14, 2009
A case in point may be the humanzee, a chimpanzee that walked upright and had a large set of human-like characteristics. Evidently, it made a huge physiological leap that should have taken hundreds of generations by normal evolution standards.

Lately the discovery of what appears to be a new species, the chupacabra, shows a similar quantum leap. The hypothesis is that it is a cross between a wolf and cayote. But that is unproven. It is definitely new.
Donutz
5 / 5 (1) Dec 14, 2009

The original question remains unanswered. How do the first male and the first female of a new species find each other and start the new species?

Well, I did suggest one mechanism farther up the discussion. Here's another: Mutations can either be dominant or recessive. If you get a dominant mutation, then you have the 'hopeful monster' scenario, and you basically require my earlier suggestion to get any traction.
If the mutation is recessive, though, it can spread through the population without necessarily causing the 'ewwwww' factor. Only when the gene becomes prevalent enough for offspring to start getting two copies will the mutation become visible, and by that point there are enough copies of the mutated gene around for multiple visible mutants to appear. Again, because the parent population will probably look at them and go 'ewwwwww', they'll have to breed with each other. Or go without.
moj85
5 / 5 (3) Dec 15, 2009
A case in point may be the humanzee...

Lately the discovery of what appears to be a new species, the chupacabra, shows a similar quantum leap. The hypothesis is that it is a cross between a wolf and cayote. But that is unproven. It is definitely new.


These are not new species, nor even real. The humanzee was a result of a media frenzy of a chimpanzee that had some weird facial features and walked upright. He was not a new species.

The chupacabra is not a new species either. Much like Bigfoot, it is just lore and legend. No one has ever documented a chupacabra skeleton or even studied one.
VeIanarris
1.4 / 5 (11) Dec 22, 2009
The chupacabra is not a new species either. Much like Bigfoot, it is just lore and legend. No one has ever documented a chupacabra skeleton or even studied one.

There not a new species but an abhoration to our lord. We know god made the universe, the world and all that lives in it, it says so in the Holy Bible and that is all that counts.
Velanarris
2.2 / 5 (10) Dec 22, 2009
There not a new species but an abhoration to our lord. We know god made the universe, the world and all that lives in it, it says so in the Holy Bible and that is all that counts.
Pay no attention to the imposteur behind the curtain.
VeIanarris
1.3 / 5 (12) Dec 23, 2009
for his name is Darwin, belive in the way and follow the witness's. They forgave me when I came out, let them forgive you
breadhead
1 / 5 (5) Jan 31, 2010
What a load of manure. An animal born with an extra leg or whatever, is not a new "Kind". What definition of evolution are we speaking of? A dog gives birth to a snake? This has never been observed. It would make headlines if it did happen. All speculation, no science here. There is absolutely no proof for evolution. We can look at the same evidence - say, the grand canyon, you say it formed by a small amount of water over millions of years, I say it formed by a lot of water in a short time, pehaps days. It is a matter of your worldview. I don't have enough faith to be an athiest/evolutionist. I wish the "Despirately hopefull to find some real evidence" evolutionists would hold back their fictional stories until they find some missing link. Cause I know they never will.