Hannah Waters at Culturing Science has nice post on an experiment designed to find out how fast a population of flies could adapt to dryer conditions. Apparently, the flies could not adapt.
We tend to take it for granted that life is robust, and will adapt: “Life will find a way”. This is true to an extent, but obviously not always:
Natural selection itself is based on three assumptions in a population. The first is that there will be variation in traits, such as multiple colors of eyes or hair. The second is that these traits be heritable through the generations, that children will inherit the traits of their parents. The third is that these variable traits have differential fitness, or that some versions of a trait might help you survive better than another. Thus certain trait variants will help its carrier organism survive better, passing that trait to its offspring which will in turn bear this trait. – Waters, 2011: When adaptation doesn’t happen.