What is evolution?

I talked in the last post about recombination, one of the evolutionary forces which change DNA sequences over time.  Selection is another, and perhaps the one that most often gets 'blamed' for the evolutionary changes that are observed by scientists.  Mutation and genetic drift are the other two.  Selection tends to get a lot of focus because it can provide a good story - we observe that some DNA has changed, and we seek an explanation, or 'reason' for the change, and selection for increased fitness is a convenient hook to hang our rationality on.  The other three forces, implicated in 'non-adaptive' evolution,  are more difficult to build a good story around, so are not so often considered.  

My favourite evolution textbook at the moment is The Origins of Genome Architecture by Mike Lynch (2007), and he makes this point very forcefully, along with some other very

 interesting observations, in the discursive chapter at the end, entitled Genomfart (you'll have to buy his book or Google it :).  It's a great book and gives clear and detailed coverage, well backed-up by references, to the mechanisms and effects of genome evolution both from the base pair up, and the population down.  Mike is particularly keen to reiterate the point that you can't understand evolution without understanding populations, the level at which genetic drift operates.  I couldn't agree more, and am hoping to start some modeling of populations in the near future, from the bottom up, to learn more about some of the properties of populations that emerge when plants are domesticated.  More of those experiments if and when the grant proposal is accepted :)

In the meantime, I am mostly concerned with some bottom-up effects, and have been looking for SNPs in cotton this week (Single Nucleotide Polymorphisms - effects of the evolutionary force of mutation).  A colleague has been puzzling over something described as 'desi cotton', trying to ascertain its genotype, and one of the places this led me was to a very interesting and useful site, the Multilingual Multiscript Plant Name Database which Michel Porcher runs.  This amazing resource lists the names of plants in over 60 languages and various scripts, and is a really world-class reference.  It's in my favourites list on the right here, because these are one of my favourite kinds of site - places where someone has really put a lot of work over a long period of time into making something comprehensive and authoritative.  When I find a site like this, I can't help wanting to tell people! 

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Lynch, M.  (2007).  The origins of genome architecture.  Sinauer Associates.