Hybrid life - 02 September 2009 - New Scientist
LOOK at the genome of a sea squirt and you'll get a nasty surprise. Half of its genes have a straightforward evolutionary history. In fairness, so does the other half. Trouble is, the two histories are completely different. It seems that sea squirts do not, as we had thought, sit among the chordates, on the same evolutionary line as humans and other vertebrates. Instead, they are the result of what happens when you fuse an ancient chordate with the ancestor of a sea urchin.
