The Accumulation of Deleterious Mutations As a Consequence of Domestication and Improvement in Sunflowers

For individuals to stay well adapted to their environment, harmful mutations must be removed from populations by natural selection. Yet, under specific circumstances that impair the effectiveness of selection, such as during the domestication of plants and animals, these harmful mutations are predicted to accumulate. Here, we report that mutations impairing protein function (non-synonymous deleterious mutations) are more abundant in domesticated sunflowers than in their wild relatives. We also identify similar patterns in other domesticated species of the sunflower family. Finally, we provide evidence that, as predicted by population genetic theory, deleterious mutations have accumulated preferentially in low recombining regions of the genome. A paucity of recombination is likely to frustrate attempts to eliminate these mutations by plant and animal breeding program, despite probable benefits to agricultural productivity.