Estimating the fitness effect of deleterious mutations during the two phases of the life cycle: a new method applied to the root-rot fungus Heterobasidion parviporum

Many eukaryote species including taxa such as fungi or algae spend a large portion of their life cycle as haploids and as diploids. Clergeot, Rode et al. derive a statistical model to test whether deleterious mutations have stronger effects in haploids than in homozygous diploids, whether they are partially recessive in heterozygous diploids and whether diploids have higher fitness than haploids on average. As an illustration, they use their model to study growth rate and the ability to degrade wood in the root-rot fungus Heterobasidion parviporum. Their model should help gaining further insights into the evolution of haploid-diploid life cycles.