Ruben C. Arslan

Correction to: reply to Woodley of Menieet al.

Proc. R. Soc. B 285 , 20180092 (Published online 21 February 2018) ([doi:10.1098/rspb.2018.0092][1])nnIn Arslan et al .’s reply to the commentary by Woodley of Menie et al ., the authors were reacting to an earlier version of their commentary than the one that was published. They only …nn [1]: http://dx.doi.org/10.1098/rspb.2018.0092

Relaxed selection and mutation accumulation are best studied empirically: Reply to Woodley of Menie et al

In their commentary, Woodley of Menie et al . [1] not only misrepresent our results and conclusions but also ignore relevant molecular genetic work. Woodley of Menie et al . incorrectly paraphrase us as dismissing that ‘modernized populations harbour historically high mutational loads. In reality, we wrote that current de novo mutational load is not unprecedented and that purifying selection in twentieth-century Sweden has not been eliminated or demonstrably relaxed compared with the historical populations we examined. Our data did not permit conclusions about accumulated genetic load, although unrelated work contradicts Woodley of Menie et al . on this matter [2]—at least if one agrees with the literature consensus that many mutations are neutral. Based on what we called ‘predictions of mutational doom by relaxed selection we had predicted smaller effects of paternal age on fitness in the twentieth century than in earlier times, but the data disconfirmed this pattern. Woodley of Menie et al . did not engage much with the evidence we presented, or other work more directly relevant for their arguments (e.g. [2])—instead, they focused on tangentially related evidence.nnWe see this as an opportunity to clarify and expand on the conclusions that can potentially be drawn from our data with respect to mutation load (see also [3]). First, we want to clearly differentiate two concepts that Woodley of Menie et al . muddle: opportunity for selection and strength of purifying selection . Opportunity for selection only measures the variation in a trait: here, components of evolutionary fitness (mortality and fertility). This term makes clear what the term favoured by Woodley of Menie et al ., Index of Biological State ( I bs), occludes, namely that it is not a measure of the strength of purifying selection: the ability of …