Title: "Can natural selection favor evolvability? Yeast prions as evolutionary capacitors"
Speaker: Dr. Joanna Masel
Place: SMITH 108; Tuesday, January 27, 2004 4:30pm


It is appealing to suppose that the rate at which a population can adapt is subject to natural selection, and that variation in the rate of adaptation might even be traced to specific "evolvability" genes. Much work in this area has focused on the properties of "mutator" genes which increase the mutation rate, and has concluded that mutator genes will be eliminated from the population. Recently, it was proposed that the ability to form the yeast prion [PSI+] may lead to an increased rate of adaptation or evolvability (True and Lindquist 2000). This comes about through the heritable but reversible expression of pre-existing but latent variation associated with sequences beyond stop codons. This mechanism differs substantially from that of mutator genes. A mathematical model is presented which calculates whether this ability is more likely to have become fixed due to chance alone or due to its evolvability characteristics. Evolvability is found to be a more likely explanation, so long as environmental change makes partial readthrough of stop codons adaptive at a frequency of at least once every million years. This suggests, for the first time, that natural selection can and has favored increased evolvability.

(This is a candidate for the Bioinformatics COALESCE hires in the School of Science. To meet with the candidate, please contact RW Doerge at doerge@purdue.edu)

See http://www.stat.purdue.edu/~doerge/BIOINFORM.D/SPRING04/sem.html for a full scheule of BIOINFORMATICS SEMINARS.