Evolutionary impact of copy number variation rates

Abstract

Objective: Copy number variation is now recognized as one of the major sources of genetic variation among individuals in natural populations of any species. However, the relevance of these unexpected observations goes beyond diagnosing high diversity.

Results: Here, it is argued that the molecular rates of copy number variation, mainly the deletion rate upon variation, determine the evolutionary road of the genome regarding size. Genetic drift will govern this process only if the effective population size is lower than the inverse of the deletion rate. Otherwise, natural selection will do.

Keywords: Birth–death process; Gene duplication; Genome size; Neutral evolution; Population genetics.

Fig. 1

Phase space between effective population size (N) and deletion rate upon duplication (λ) showing the region where genome size can increase by genetic drift (shaded region). The solid line corresponds to the limit λN = 1/12 (strict), whilst the dashed line to λN = 1 (soft). λ ≫ μ is assumed. Six different organisms are contextualized (S. enterica, S. cerevisiae, D. melanogaster, C. elegans, A. thaliana, and H. sapiens). All λ values correspond to empirical estimations, except the value for the plant, which is a prediction