Prevalence of loss-of-function alleles does not correlate with lifetime fecundity and other life-history traits in metazoans.

Background: Natural selection is possible only because all species produce more offsprings than what is needed to maintain the population. Still, the lifetime number of offspring varies widely across species. One may expect natural selection to be stronger in high-fecundity species. Alternatively, natural selection could be stronger in species where a female invests more into an individual offspring. This issue needed to be addressed empirically.

Results: We analyzed the prevalence of loss-of-function alleles in 35 metazoan species and have found that the strength of negative selection does not correlate with lifetime fecundity or other life-history traits.

Conclusions: Higher random mortality in high-fecundity species may negate the effect of increased opportunity for selection. Perhaps, invariance of the strength of negative selection across a wide variety of species emerges because natural selection optimized the life history in each of them, leading to the strongest possible competition.

Reviewers: This article was reviewed by Nicolas Galtier and I. King Jordan.