[Justin DiVirgilio]

Justin DiVirgilio  asked the Naked Scientists:
   
Dear Naked Scientists,

On a recent programme you featured a story (Evolution in a Bottle) about Richard Lenski's research into the rate of genetic mutations in E. coli bacteria.

What is the implication of his findings - that a mutation involved in DNA metabolism could increase the chances of mutations happening elsewhere in the genome, hence changing the rate at which mutations occur - for the use of the molecular clock concept for dating the divergence of distinct population groups (e.g. in humans) or of separate species?

Thank you all for producing such a great show.

Cheers,
Justin DiVirgilio


What do you think?

[Jessica H]

I think you're right that it would throw a wrench in the process, but the same could be said for a period of natural disaster, when natural selection would have to be rapid for an organism to survive. The idea of a molecular clock in the sense of really telling evolutionary time seems to have too many limitations to be really useful.

On the other hand, using the molecular clock idea just to determine relationships still should work. You only look at one protein at a time, so even if something was causing mutations all over the genome, it would probably hit that specific protein once, so maybe it wouldn't throw off the molecular clock all that much. For example, if apes and humans have 1 difference between their cytochrome c proteins, and horses and humans have 12 differences, then one extra mutation doesn't really confuse the issue in the long view of how we are related.