Chicken study reveals evolution can happen faster than thought(ox.ac.uk)
ox.ac.uk
Chicken study reveals evolution can happen faster than thought
http://www.ox.ac.uk/news/2015-10-28-chicken-study-reveals-evolution-can-happen-much-faster-thought-0
9 comments
The chicken crossed the road to speed up the process of evolution and natural selection.
[deleted]
> Previously, estimates put the rate of change in a mitochondrial genome at about 2% per million years. At this pace, we should not have been able to spot a single mutation in just 50 years, but in fact we spotted two.'
Doesn't sound as spectacular as the rest of the article.
Doesn't sound as spectacular as the rest of the article.
So basically n=12, and they saw 2 instances of one thing and 1 instance of another. Sure, maybe p<0.05 but a larger sample size wouldn't go astray.
Previous discussion: https://news.ycombinator.com/item?id=10462246
Not a dupe because it didn't get significant attention (and since it looked good, we invited dnetesn to repost it). But we did merge the two comments there into this thread.
Then how fast is thought?
How do you even measure the speed of thought?
And who cares what chickens think?
How do you even measure the speed of thought?
And who cares what chickens think?
A new study of chickens overturns the popular assumption that evolution is only visible over long time scales.
And yet the popular assumption remains the same, because it is the ignorance of the general public that perpetuates it and not the lack of research.
The solution: stop calling it popular assumption and start treating it as fact, journalists.
And yet the popular assumption remains the same, because it is the ignorance of the general public that perpetuates it and not the lack of research.
The solution: stop calling it popular assumption and start treating it as fact, journalists.
I've read your comment three times and I still have no idea what it's supposed to say.
I think the commenter is saying that the general public thinks that evolution is an assumption instead of a fact and is wishing that journalists would start writing about evolution using language that reaffirms that it is a fact and not an assumption.
It's been known for a long time that much of evolution happens in spurts. When the environment is fairly stable evolution is a slow refinement toward local maxima. When the environment changes there's much more selection pressure and evolution happens much more quickly.
So, this one study doesn't tell us much new about the speed of evolution (because we already knew), and there's no reason to think this study will do any more to correct common misconceptions than previous science.
So, this one study doesn't tell us much new about the speed of evolution (because we already knew), and there's no reason to think this study will do any more to correct common misconceptions than previous science.
Maybe that's what just_curioussss meant, but he wrote the opposite.
I think he's assuming they're overturning a popular assumption with another piece of information that will just become another 'popular assumption' instead of explicitly stating "This new fact overturns the popular assumption..."
I never really understand the view that evolution can only happen over long timescales. From a theoretical perspective, natural selection can obviously have a huge effect over a single generation.
Imagine that the ability to swim was an extremely heritable, genetically determined trait. A flood on an island could select for the swimming gene in about 30 minutes.
Imagine that the ability to swim was an extremely heritable, genetically determined trait. A flood on an island could select for the swimming gene in about 30 minutes.
Selection cannot act over a single generation, if by 'act' you mean that an allele fixes in the population (reaches 100% frequency). If a new mutation appears in a single individual, it cannot in the next generation be present in every individual, unless the founder's progeny replace everyone else's. In any event this would be a disaster for overall fitness, since the level of genetic diversity would collapse.
In general selection propagates a variant exponentially fast based on the reproductive advantage it confers. If you make 1000 progeny and I make 1001, my reproductive advantage is 1.001 - every generation the frequency of my variant relative to yours goes up by this factor. If I start at frequency f and my advantage is s, it will take n=ln(1/f)/ln(s) generations to fix (approximately). For the example above with f=1%, this gives about 4607 generations.
There are other factors, notably population size. For a population of size N, the initial f will be 1/N. If N is small, f will be larger and selection will take less time. On the other hand, in a small population, genetic drift is stronger, and weakly selected variants are more likely to be eliminated by drift before they can fix.
In general selection propagates a variant exponentially fast based on the reproductive advantage it confers. If you make 1000 progeny and I make 1001, my reproductive advantage is 1.001 - every generation the frequency of my variant relative to yours goes up by this factor. If I start at frequency f and my advantage is s, it will take n=ln(1/f)/ln(s) generations to fix (approximately). For the example above with f=1%, this gives about 4607 generations.
There are other factors, notably population size. For a population of size N, the initial f will be 1/N. If N is small, f will be larger and selection will take less time. On the other hand, in a small population, genetic drift is stronger, and weakly selected variants are more likely to be eliminated by drift before they can fix.
I think it's important to note that evolution is really just the change of the availability and distribution of heritable traits in a population over time. To me, it seems fairly obvious that there are slow and fast components that can effect this, and therefore evolution plays out at multiple timescales simultaneously.
Your example is one of pretty fast restriction of traits: The trait of not being able to swim pretty quickly disappeared. However, how long did it take for the ability to swim to be present in the population in the first place? How long will it take for individuals to exist without the ability to swim after the event?
Your example is one of pretty fast restriction of traits: The trait of not being able to swim pretty quickly disappeared. However, how long did it take for the ability to swim to be present in the population in the first place? How long will it take for individuals to exist without the ability to swim after the event?
Yes, makes me think that maybe evolution can be looked at as operating in two ways, temporal random variations that aren't a guaranteed to be long term directions (presumably the genes passed in this test could just as easily breed out) and the fossil based evolution that we understand pretty well.
Of course IANAEB so maybe someone can give us a more detailed explanation...
Of course IANAEB so maybe someone can give us a more detailed explanation...
Url changed from http://phys.org/news/2015-10-chicken-reveals-evolution-faste... to a more original source.
What are the implications for dates obtained with mitochondrial DNA? I suppose the answer for anything beyond chickens or maybe other birds is "More research needed".