Well the cover article in this week's New Scientist is perfectly timed for our class as it reviews whether the conventional 'tree of life' model that dates back to Darwin is still a useful metaphor or not. I think everyone could benefit from a quick read of the article, especially since it isn't hidden behind their usual subscription barrier. The article also contains a lot of interesting links to research in a range of different areas.
(I)t is clear that the Darwinian tree is no longer an adequate description of how evolution in general works. "If you don't have a tree of life, what does it mean for evolutionary biology?" asks Bapteste. "At first it's very scary... but in the past couple of years people have begun to free their minds." Both he and Doolittle are at pains to stress that downgrading the tree of life doesn't mean that the theory of evolution is wrong - just that evolution is not as tidy as we would like to believe. Some evolutionary relationships are tree-like; many others are not. "We should relax a bit on this," says Doolittle. "We understand evolution pretty well - it's just that it is more complex than Darwin imagined. The tree isn't the only pattern."