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Asked by lowkey to Ed, Katie, Sam, Steve, Vera on 13 Jun 2011. This question was also asked by bobsthe1.
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Steven Daly answered on 13 Jun 2011:
That is a great question. There are a number of ways to evolve faster. One of these is to have a short lifetime. So for example flies that only live for a few weeks will evolve faster because they can have many generations in a short space of time.
For evolution to occur there has to be something to cause it, some factor from the outside world. My favourite example of this is bacteria, which have developed antibiotic resistance because of us using them so frequently and killing them. Obviously a bacterium that can survive antibiotics and generate a new population that will also be resistant to antibiotics. This can occur very quickly because it is an extreme pressure on the bacteria, and is how superbugs like MRSA evolved.
So, I guess my answer would be it depends. Evolution will take as long or as short a time as it needs to deal with the whatever problem it is up against. If it is an extreme cause of evolution, then you either evolve quickly, or become extinct.
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Katie Marriott answered on 13 Jun 2011:
This is a brilliant question and to be honest I have no idea!
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Sam Tazzyman answered on 13 Jun 2011:
Good question: this is actually quite a controversial topic in evolutionary theory. Many scientists think about this and debate it. How well a species can evolve is called its “evolvability”. The forces that change the evolvability of a species over time are not known for certain yet. So your question is right at the cutting edge of evolutionary science!
I agree with what Steven says that some species will evolve faster because they have shorter lifespans, and with what he says about strong pressures (eg antibiotics on bacteria) making things evolve faster.
But there are other factors too. One of them is the size of a population. If there is a big population of animals then there is more variety and so more chance that the characteristic the will evolve is already there. You can see this if you think about people: Imagine you’ve got two groups of people, and one of the groups has 10 people, and the other has 1,000,000 people. Which group do you think is more likely to contain at least one person over 6 feet tall? It’s the group with 1,000,000 people. Therefore if (for some reason) there was an evolutionary advantage to being tall then the larger group would be more likely to adapt faster.
Another thing that affects the evolvability of a species is the mutation rate. When organisms reproduce they have to copy their genes and pass them on to their offspring. An example of this is in humans: you have half your Mum’s genes and half your Dad’s. But sometimes the copying isn’t perfect, and so there is a slight mistake. This is called a mutation. Most often these mistakes make no difference, or are even slightly bad, but sometimes they make a better genetic code than before the mistake. This is where the variety comes from which evolution works on. How often these copying mistakes are made is called the “mutation rate”. Species with higher mutation rates have more copying mistakes, and so have more variety, and so have higher evolvability. But scientists don’t really know how the mutation rate changes or why or when.
So your question is a fascinating one. I hope that’s managed to answer it a bit – there are lots of things on this topic that people don’t really know for sure!
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Ed Morrison answered on 13 Jun 2011:
Steven and Sam give really good answers so I can’t add much to them. I would say though that evolving is not necessarily a good thing. Animals like jellyfish and crocodiles and sharks don’t seem to have changed much in millions of years. This is because they are so successful they don’t need to evolve much more.
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Vera Weisbecker answered on 13 Jun 2011:
You can, although speed is relative. Sometimes species evolve at a really fast rate when you look at their genes (the kind of process that Sam explained) but they stay identical in size and shape and colour. That means that sometimes you have many species that you can’t tell apart (did you know that there are nearly 2300 mouse species, most of which look more or less like a mouse or rat?) although their DNA is really different. On the other hand, you can have humans and chimpanzees, who are genetically almost identical but look pretty different. So, you can evolve faster either on DNA level, shape/size level, or both.
Comments
Jim commented on :
Just wandering between zones….
I have images of the X-men First Class character Armando Muñoz (aka ‘Darwin’) in my head, with his mutation being that he could ‘adapt’.
In the field of bacterial evolution, in which I work, there has been some very exciting work in recent years looking at evolvability. We often find strains of bacteria that we called ‘hyper-mutable’, which means they more readily undergo genetic mutations. This is actually because of a defect in their ability to guard against too many mutations, which can be damaging. However, in extreme environments or the pressure to resist and antibiotic or die, it could be that this is a desirable way of doing better than the other cells around you.
In March this year a nice study reported that described some strains of E. coli that when put into a head-to-head competition with some related strains of E. coli (cousins if you like), they weren’t quite as competitive, they didn’t grow as quick, so you might call them ‘early losers’. However, over time, these less competitive strains were the only ones left, they were the ‘eventual winners’. The reason for this is that they had a greater potential for further adaptation, in effect, they had better evolvability.
There are also studies that show how genetic variation (something that increases the potential to overcome and exploit a new environment) can be maintained and stored, but not used. Sometimes an organism is well suited to its environment, and wants to keep it that way, so the organism itself appears to change very little for millions of years. But then, under conditions of considerable stress, the variation that has been ‘stored up’ can be released generating a whole range of new and interesting mutants, some of which might be better adapted to the new changed environment.
Some of these ideas still have to be explored more fully, but it’s never been a more exciting time to study evolution.