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As far as I understand, various abilities like flying, sight, hearing etc. were caused by slow evolution, where those with a greater ability to to these things had better chance of survival. (If this assumption is wrong, then I am happy to delete this question).

Are there, however, any documented examples of by evolutionary leaps being made, over the course of just a few generations? I understand, that some abilities have a tipping point where one gets the ability suddenly, but there is not a lot of physiological change made. An example of this would be the ability to climb a tree, which could suddenly be possible if the body weight is reduced with just a few percent. What my question is about, are sudden changes to the characteristics of a creature.

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How sudden is sudden enough for you? –  kmm Jan 22 '12 at 23:40
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@Kevin It depends upon the magnitude of change in the characteristics of the creature. –  David Jan 23 '12 at 1:40
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E. Coli being able to subsist on cellulose? That was a nice laboratory controlled experiment, showing the 2 mutations change required for that. Although that was only rapid in chronological time, since it was 40,000 generations of bacteria. –  Brightblades Jan 23 '12 at 13:06
    
@Brightblades This is certainly interesting, but with this question I was primarily thinking about things happening over the course of tens of generations. On the other hand, what really counts for the survival of the fittest is of course adaptability to adapt in chronological time. How long time did this adaptation take? –  David Jan 23 '12 at 19:37
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@David I don't recall precisely, but it was over a period of years (one scientist doing the experiment). It's only been going for 24 years: en.wikipedia.org/wiki/E._coli_long-term_evolution_experiment –  Brightblades Jan 24 '12 at 12:47

5 Answers 5

up vote 7 down vote accepted

@kmm and @shigeta provided you with a nice observational account of sudden leaps in large organisms. However, if you want to look at where this is the norm and try to build a mathematical theory then you need to look at something much smaller; the prime candidate is affinity maturation.

In the human immune system, when exposed to an antigen B cells produce antibodies. If it is your first exposure to the antigen then the antibodies produced will probably have very low binding affinity. However, after some exposure time, your B cells will start to produce antibodies with much higher affinities for the antigen and thus you will be able to better fight off the disease. The cool part, is that the antigen produced is tune via an evolutionary process!

There is differential survival, with only antibodies with the highest affinity being able to survive. Variability is introduced by a very high mutation rate in the complementarity determing region (CDR). (Tonegawa, 1983). The length of this evolutionary process is very short, typically a local equilibrium is found after only 6-8 nucleotide changes in CDR (Crews et al., 1981; Tonegawa, 1983; Clark et al., 1985), so you need only a few point mutations to quickly develop a drastically better tuned antibody.

The standard mathematical model for this is Kauffman's NK model. With a protein sequence on $N$ sites, we say that evolution is fast (and we have a sudden leap) if after our fitness landscape changes, we can get to a new local equilibrium in a number of generations that scales with $\log N$. Kauffman & Weinberger (1989) showed how this model can be used to study affinity maturation, and showed that to achieve a sudden leap we need high epistasis and low correlations between pointwise mutants. In particular, their model suggests that typical epistasis in the CDR is on the order of 40 proteins (out of the total 112 proteins in the CDR).


References

Clark, S.H., Huppi, K., Ruezinsky, D., Staudt, L., Gerhard, W., & Weigert, M. (1985). Inter- and intraclonal diversity in the antibody response to influenza hemagglutin. J. Exp. Med. 161, 687.

Crews, S., Griffin, J., Huang, H., Calame, K., & Hood, L. (1981). A single V gene segment encodes the immune response to phosphorylcholine: somatic mutation is correlated with the class of the antibody. Cell 25, 59.

Kauffman, S. and Weinberger, E. (1989) The NK Model of rugged fitness landscapes and its application to the maturation of the immune response. Journal of Theoretical Biology, 141(2): 211-245

Tonegawa, S. (1983). Somatic generation of antibody diversity. Nature 302, 575.

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With all due respect, a few of these answers, although good examples of selection at work, were voted too high given the specific question asked: “documented examples of by evolutionary leaps being made, over the course of just a few generations?”

Sometimes we’re better being honest and identifying something as an ‘unknown’ or ‘yet to be observed’ than to list (and have people up-vote) poor examples. We do evolution a dis-service when we promote poor examples as answers to questions like these.

To expound:

The cricket losing the ability to sing (communicate) examples does demonstrate mutation and natural selection at work, but really only shows the REDUCTION of a capability. It’s not a good example of evolutionary leaps. It only happens to be beneficial in one SPECIFIC context. This would be analogous to tanks on a battle-field which communicate via radio, vulnerable to radio-frequency tracking missiles. Any tank with a broken radio would not be vulnerable to these missiles. Although technically ‘beneficial’ in this context, it’s an example of a loss of capability, not a gain of capability. We need to promote examples of mutations that PRODUCE capabilities.

Lactase persistence example likewise is an example of mutation and natural selection, but not a good example of a GAIN in functionality (as some have pointed out in the comments). It’s technically the loss of the normal switching-off mechanism of lactase production following weaning. So once again, a loss, that happens to have a beneficial side-effect.

Regarding punctuated equilibrium, I’m not surprised that was mentioned but was surprised that it got some votes. It’s a hypothetical explanation for why we see gaps in the fossils, but not conclusive ‘evidence’, or in the case of the question asked not “documented examples”.

Again: We do evolution a dis-service when we promote poor examples as answers to questions like these. Let’s focus on quality, not quantity when it comes to presenting evidence for evolution.

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Can you please improve your answer and especially remove the belittling comments against other users? This not necessary and does not contribute to the answer. –  Chris Sep 26 at 14:06
    
Tried rewording it a little, removed specific's handles. Better? –  or1equals1 Sep 26 at 14:35

I think that this might refer to evolution in punctuated equilibrium as described by Stephen Gould et al way back in the 70s. If this is the case, it refers more to the idea that changes and speciations can be quite rapid in time and for long periods you don't see morphological changes or speciation events in the record.

If so, then this is influenced by the study of evolution in cases where there are large changes in the environment very rapidly. The classic case is when there is a bare island and new animals arrive only rarely. This is all very much inspired by Darwin's observations in the Galapagos, but has since been studied quite a bit. In such cases you see just handful of sets of birds suddenly appear and you find a finch that can scrape bugs out of bark, another that can dig into narrow niches in the rock for food, where in a broader ecosystem two completely different species would be utilizing those 2 food sources.

It should be said that no evolutionary leap should be understood as an acceleration or deceleration of evolution. Only a change in the rate of adoption of variations because of a wider set of possible advantages those variations can represent.

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Even under punctuated equilibrium, acquisition of new traits happens over a period of thousands of generations, not “just a few generations”. It is punctuated on the geological timescale only. –  Konrad Rudolph Jan 31 '12 at 12:24

The ability to drink milk by the inheritance of lactase persistence via a single allele change. Sociology and genetic studies have shown that the immigration of a few lactose tolerant people into large non-lactose tolerant populations, the lactase persistence gene quickly spreads through the population, a sign of a dominant mutation and survival of the fittest at work.

Not in the mood to dissect the papers but here are a few commentaries:

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Is lactose intolerance really likely to stop an organism reaching reproductive age and being successful? –  Rory M Jan 23 '12 at 9:00
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There is a good amount of genetic evidence that does suggests so. Examples of natural selection are seen in pastoral communities that shifted from a farming community to a dairy community. Unfortunately I don't know the field well enough to find good sources. –  bobthejoe Jan 23 '12 at 10:11
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This is selective sweep (i.e. a given allele’s abundance is sweeping through a population via selection). But that isn’t in itself a sudden leap in evolution since the allele is already in existence (= “has already evolved”). –  Konrad Rudolph Jan 31 '12 at 12:22
    
@Konrad: However, the lactase persistent allele itself is the result of a single spot mutation that is believed to be of rather recent origin. (Some studies suggest it happened around ten thousand years ago, which is an eyeblink in evolutionary timescales.) This is another case of evolution via function loss: the mutation that causes adult lactose tolerance basically disables the switch that, in most mammals, turns off lactase production after weaning. –  Ilmari Karonen May 4 '12 at 23:10

Zuk et al. (2006) document the rapid evolution of song-less crickets in a population of crickets that previously used song for courtship.

In less that 20 generations, over 90% of male crickets of the species Teleogryllus oceanicus evolved to a novel morphology ("flatwing") that rendered them unable to call to females. They hypothesize that this shift resulted from the presence of an North American invasive "acoustically orienting parasitoid fly."

Basically the flies detect calling males and parasitize them, rendering them unable to reproduce. Were it not for the presence of the parasitoid fly, the flatwing flies would likely not have survived. Non-calling individuals rely on the presence of calling males to bring females near for mating.

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Excellent example! –  David Jan 23 '12 at 1:42
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Even though it is a nice example of evolutional change, I am just wondering whether the loss of a previously existing ability to produce songs can be seen as an evolution, not devolution or involution? –  Alexander Galkin Jan 23 '12 at 13:32
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Evolution is just descent with modification -- adding or subtracting doesn't matter. –  kmm Jan 23 '12 at 15:26
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@Alexander Galkin: wouldn't you consider evolution a fish evolving into a land animal and losing the ability to breathe under water? –  nico Jan 28 '12 at 11:52

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