Paternal age effects on offspring fitness in four populations - online supplementary website - see https://rubenarslan.github.io/paternal_age_fitness for browsable site. ; Other ; RCA thanks Paul-Christian Bürkner, Jarrod Hadfield, Ben Bolker and Holger Sennhenn-Reulen for their statistical packages and advice, and Claude Bhérer, Peter Visscher and three anonymous reviewers for their helpful comments on earlier versions of this manuscript. MM acknowledges the support of the European Research Council grant 336475. CA and EMF acknowledge financial support from the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no. 340-2013-5867.