short-term examples of evolution(ary adaptation)

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pr0xyt0xin

Registered Member
Can anyone think of examples, (more specifically cite the data from examples) of evolution in the short term. If I might be so bold, I'm looking for the most drastic examples of a species adapting to their environment in the shortest amount of time. Possibly due to drastic changes in their environment due to human impact.

e.g., birds wing spans changing due to telephone poles.

It took humans millions of years to evolve from apes because their environment changed very steadily. But if a creature's environment changes much more rapidly, it should speed up the process substantially right?
 
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pr0xyt0xin said:
But if a creature's environment changes much more rapidly, it should speed up the process substantially right?
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Either that or the species becomes extinct. Generally, very rapid changes in the environment will cause large extinctions and then the surviving animals will evolve over time to fill the ecosystem or niche that the extinct animals use to utilize.
Take the extinction event at the end of the last ice age. 12,000 years ago North America had the diversity of animal life that rivaled Africa. In the 12,000 years after the extinction event there is only a small percentage of species that inhabited North America compared to the time before 12,000 years ago. Probably in 200,000 to 500,000 years there would again be a lot of diversity, if we did not put a stop to it.
 
That's not really how evolution works, pr0xyt0xin. Evolution is the product of variation within a population that is selected by specific environments. If there isn't variation that is selected by an environment, then there is no evolution. In the case of evolution, the arbiter of selection is death.

For example, dodos didn't evolve when faced with humans and rats, they just all died.

Edit: See origin above.
 
I may not be using accurate phrasing or concepts, so apologies for that. But I feel like the question is still there. Mammoths "became" woolly over generations because of cold weather. The mammoths with the least wool were less fit for their environments and thus never got a chance to reproduce.

So yeah, major events would undoubtedly cause mass extinction (we have a few examples of that in Earth's history) but what about the slightly less major ones? I mean, many will still die off. But that alone will reveal changes in the species within only a few generations would it not?

The best example of what I'm referring to I can think of is Darwin's finches. It would have taken many generations to see changes in their beaks, etc. So, if faced with major events (like the arrival of a new species), they should "evolve" much faster. Many die off. And, in far fewer generations we might see apparent physiological changes that would match up with those environmental changes.
 
pr0xyt0xin said:
The best example of what I'm referring to I can think of is Darwin's finches. It would have taken generations to see changes in their beaks, etc. So, if faced with major events (like the arrival of a new species), they should "evolve" much faster. Many die off. And, in far fewer generations we might see apparent physiological changes that would match up with those environmental changes.
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Some of the best examples of rapid change due to environmental changes are those same finches. You should look into them.
 
Moths changed their coloring to adapt to soot covered trees in the wake of industrialization.
Flies, rats, and lice all evolved human specific species.
Also look up the speciation of cichlids in Lake Nagubago. Many of these species of fish evolved within the last 4,000 years.
 
pr0xyt0xin said:
I may not be using accurate phrasing or concepts, so apologies for that. But I feel like the question is still there. Mammoths "became" woolly over generations because of cold weather. The mammoths with the least wool were less fit for their environments and thus never got a chance to reproduce.

So yeah, major events would undoubtedly cause mass extinction (we have a few examples of that in Earth's history) but what about the slightly less major ones? I mean, many will still die off. But that alone will reveal changes in the species within only a few generations would it not?

The best example of what I'm referring to I can think of is Darwin's finches. It would have taken many generations to see changes in their beaks, etc. So, if faced with major events (like the arrival of a new species), they should "evolve" much faster. Many die off. And, in far fewer generations we might see apparent physiological changes that would match up with those environmental changes.
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One example of rapid evolution is the development of drug resistance by microbes and by cancer cells. This is in part due to the rapidity with which they reproduce, so you can observe the results of many generations in a short spell of time. In the case of cancer, I think there is also a more rapid rate of mutations, which more rapidly tries out a wide range of variants of the original cell.
 
spidergoat said:
Moths changed their coloring to adapt to soot covered trees in the wake of industrialization.
Flies, rats, and lice all evolved human specific species.
Also look up the speciation of cichlids in Lake Nagubago. Many of these species of fish evolved within the last 4,000 years.
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https://en.wikipedia.org/wiki/Peppered_moth_evolution

That's perfect. Examples like this are what I'm looking for. This moth's appearance changed drastically (visibly even) due to a major ("external") change in its environment. The process took less than 200 years. I mean, might not be so drastic as apes to humans, but to the moth community I bet it seemed pretty drastic.
 
spidergoat said:
Moths changed their coloring to adapt to soot covered trees in the wake of industrialization.
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In the interest of full disclosure, there has been a lot of criticism of this finding; it is not nearly as cut-and-dry as it seems.

The geographic distribution of melanic peppered moths did not fit the theory: the frequency of melanics was not as high as it should have been in some places, and higher than it should have been in others. Furthermore, melanism is not correlated with lichen cover; in the U.K., it declined before lichens returned to the trees, while in the U.S., it occurred despite the presence of lichens and declined without any perceptible changes in lichen cover. Finally, peppered moths do not normally rest on tree trunks: instead, they normally rest under horizontal branches high in the canopy, not where Kettlewell and his successors had carried out their experiments on selective predation.

These findings do not entirely rule out a role for cryptic coloration and selective predation in industrial melanism, but at the very least they deprive Kettlewell’s explanation of empirical support. As one recent review concludes, “there is little persuasive evidence, in the form of rigorous and replicated observations and experiments, to support this explanation at the present time”
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http://www.discovery.org/a/590

You can find a lot of articles going both ways. But the issue is subtle, resulting in relatively long explanations that seem to dilute a - heh- black and white answer.
 
But for a population to undergo an evolutionary change, doesn't that population have to be isolated and/or undergo a stress? I mean, a random mutation in a few individual of the population the size of China, I wouldn't really expect it to get expressed in later generations. But isolate those individuals on a island, and the mutation could very well get expressed. And, "Survival of the fittest" doesn't really say anything for evolutionary change, does it? -- but rather just who survives in a population??

(these are questions, now!)
 
Isolation does not require geographical isolation, though that is the most obvious kind.

If the mutation confers significant advantages then there is a reasonable chance that it will spread throughout a population. The size of the population is almost irrelevant. The key stages are immediately after the mutation appears, since chance can play a dominant role on whether or not the mutation is passed on.

Survival of the fittest says that evolution will proceed in the direction that favours those variations that provide a benefit in that environment. So, in one sense, it says everything there is to say about evolution.
 
Nacho said:
But for a population to undergo an evolutionary change, doesn't that population have to be isolated and/or undergo a stress? I mean, a random mutation in a few individual of the population the size of China, I wouldn't really expect it to get expressed in later generations. But isolate those individuals on a island, and the mutation could very well get expressed. And, "Survival of the fittest" doesn't really say anything for evolutionary change, does it? -- but rather just who survives in a population??

(these are questions, now!)
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No isolation is required, or stress. Random mutations do proliferate, in fact this process is so reliable we can use it like a genetic clock. Mutations can be neutral and spread anyway. Evolution is any change in the gene pool, not just advantageous ones.
 
Ophiolite said:
Survival of the fittest says that evolution will proceed in the direction that favours those variations that provide a benefit in that environment. So, in one sense, it says everything there is to say about evolution.
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Not quite, since there is a lot of potential for drift through neutral mutations.
 
islands:
wrangel island mammoth
Channel Islands mammoth

isolation with limited resources seems to lead to fairly rapid shrinking of descendants ?
 
PhysBang said:
Not quite, since there is a lot of potential for drift through neutral mutations.
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Hence my qualification "in one sense". Also, Nacho seems relatively new to evolutionary theory. I did not wish to over immerse him at first sitting.
 
spidergoat said:
No isolation is required, or stress. Random mutations do proliferate, in fact this process is so reliable we can use it like a genetic clock. Mutations can be neutral and spread anyway. Evolution is any change in the gene pool, not just advantageous ones.
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Then how does a random mutation get passed on non-randomly and concentrated in descendants if the descendants are not isolated? (and I'm saying that a random mutation is just that -- a mutation to 1 (certainly not many) individual)

**EDIT** I didn't say that very well. I didn't mean how the mutation would get concentrated into the person's descendants, rather how it would get concentrated into the population to follow. Afterall, the mutation originally affected only 1 person. Through offspring, and mating with another person w/o the mutation, it would seem to me that mutation would get diluted into the population afterwards.
 
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Nacho said:
Then how does a random mutation get passed on non-randomly and concentrated in descendants if the descendants are not isolated? (and I'm saying that a random mutation is just that -- a mutation to 1 (certainly not many) individual)

**EDIT** I didn't say that very well. I didn't mean how the mutation would get concentrated into the person's descendants, rather how it would get concentrated into the population to follow. Afterall, the mutation originally affected only 1 person. Through offspring, and mating with another person w/o the mutation, it would seem to me that mutation would get diluted into the population afterwards.
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It gets passed on randomly through reproduction. Any given population can be traced to just a few founding individuals. All living humans are probably the decedents of a single male who lived just 300K years ago.
 
spidergoat said:
It gets passed on randomly through reproduction. Any given population can be traced to just a few founding individuals. All living humans are probably the decedents of a single male who lived just 300K years ago.
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Then let me rephrase my question. How then can that 1 random mutation, that affected 1 individual only, be expressed to the population of a whole that follows? I don't see how that is possible -- to randomly pass it down to descendants and it expressed to the population as a whole. Please tell me the mechanics of that.

Think of the mutation as one that effects the expression of a gene (though I don't know if that is possible). Counting in a mate there is only a 50% possibility that mutation gets passed on to a descendant, but counting 2 copies each of the gene, a 25% chance. That is not going to get expressed to the population as a whole to where everybody has that mutation.

All living humans are probably the decedents of a single male who lived just 300K years ago.
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Is that with or without an isolation event happening?
 
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