Wednesday, September 27, 2006

Epistasis correlates with genomic complexity   posted by Razib @ 9/27/2006 01:07:00 AM

From PNAS:
Simpler genomes, such as those of RNA viruses, display antagonistic epistasis (mutations have smaller effects together than expected); bacterial microorganisms do not apparently deviate from independent effects, whereas in multicellular eukaryotes, a transition toward synergistic epistasis occurs (mutations have larger effects together than expected). We propose that antagonistic epistasis might be a property of compact genomes with few nonpleiotropic biological functions, whereas in complex genomes, synergism might emerge from mutational robustness.

Some have argued that synergistic epistasis is the way that "sex pays off" for complex organisms. Sexual reproduction tends to break apart superfit correlations of alleles, but synergistic epistasis is a way to recoup this loss (and evade Muller's Ratchet). A figure below the fold....

Related: Through the rugged roads of gene land.