directional epistasis
Agrawal AF & Whitlock MC 2010 Environmental duress and epistasis: how does stress affect the strength of selection on new mutations? TREE 25:450-458.
- when Sanjuan and Elena plotted the average epistasis of each species against the species genetic complexity, they found a tight linear relationship between the two
- the most complex species (Drosophila) had negative epistasis
- the RNA virus had significantly positive epistasis
- in the few years since this review, however, other data on the same taxa have been collected which sometimes give different results from those available earlier
- if these new data and insights are accounted for, the significance of the relationship between genomic complexity (as defined in [39]) and the sign of the average epistasis is much weakened
- excluding the virus data from this analysis leaves no evidence for a broader relationship between complexity and epistasis
- one other caveat should apply to any interpretation of almost all of the available studies of epistasis with deleterious alleles
- the experimental designs of these studies allowed some opportunity for particularly bad genotypes to be removed or reduced in frequency by some natural selection
- most studies of epistasis are biased towards finding estimates of the interactions between loci that are too positive
