TY - JOUR T1 - How much does <em>N</em><sub><em>e</em></sub> vary among species? JF - bioRxiv DO - 10.1101/861849 SP - 861849 AU - Nicolas Galtier AU - Marjolaine Rousselle Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/05/15/861849.1.abstract N2 - Genetic drift is an important evolutionary force of strength inversely proportional to Ne, the effective population size. The impact of drift on genome diversity and evolution is known to vary among species, but quantifying this effect is a difficult task. Here we assess the magnitude of variation in drift power among species of animals via its effect on the mutation load – which implies also inferring the distribution of fitness effects of deleterious mutations (DFE). To this aim, we analyze the non-synonymous (amino-acid changing) and synonymous (amino-acid conservative) allele frequency spectra in a large sample of metazoan species, with a focus on the primates vs. fruit flies contrast. We show that a Gamma model of the DFE is not suitable due to strong differences in estimated shape parameters among taxa, while adding a class of lethal mutations essentially solves the problem. Using the Gamma + lethal model and assuming that the mean deleterious effects of non-synonymous mutations is shared among species, we estimate that the power of drift varies by a factor of at least 500 between large-Ne and small-Ne species of animals, i.e., an order of magnitude more than the among-species variation in genetic diversity. Our results are relevant to Lewontin’s paradox while further questioning the meaning of the Ne parameter in population genomics.Competing Interest StatementThe authors have declared no competing interest. ER -