Estimation of spontaneous genome-wide mutation rate parameters: whither beneficial mutations?

Empirical estimates of genome-wide mutation rates and of the distribution of mutational effects are needed to illuminate various topics ranging from evolutionary biology to conservation. Methods for inferring genome-wide mutation parameters are presented, and results stemming from these studies are reviewed. It is argued that, although most if not all mutations detected in mutation accumulation experiments are deleterious, the question of the rate of favourable mutations (and their effects) is still a matter for debate.