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How Much Does N_e Vary Among Species?

ABSTRACT: Genetic drift is an important evolutionary force of strength inversely proportional to N_e , 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. To this aim, we analyze the nonsynonymous (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 distribution of fitness effects 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 nonsynonymous mutations is shared among species, we estimate that the power of drift varies by a factor of at least 500 between large-N_e and small-N_e 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 N_e parameter in population genomics.

SUBMITTER: Galtier N

PROVIDER: S-EPMC7536855 | biostudies-literature |

REPOSITORIES: biostudies-literature

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How Much Does N_e Vary Among Species?

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Dataset Information

How Much Does Ne Vary Among Species?

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OmicsDI is part of the ELIXIR infrastructure

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How Much Does N_e Vary Among Species?