I'm not too familiar with algae, but I can take a guess as to a
mechanism. Its well known that UV radiation can induce gene
activation. A good example is the UV activation of latent viruses
such as herpes simplex and bacteriophage lamda. Could clumping be an
evolutionary adaptation? What if UV radiation induced damaged
activated a gene for a clumping protein. A clumped bunch of algal
cells would be more resistant to UV light then dispersed cells because
the cells at the center of the clump would be shaded from the
radiation. Cells which had the fastest clumping response would
probably be more likely to end up in the center of the clump. Cool!
Jay Mone'
