National Academy of Sciences, Proceedings of the National Academy of Sciences, 20(112), 2015
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Significance A deleterious mutation that is recessive is hidden in individuals containing only one copy (i.e., heterozygotes); however, individuals containing two copies (i.e., homozygotes) suffer negative effects. This class of mutation is responsible for a number of human genetic disorders, including cystic fibrosis and Tay-Sachs, in addition to causing the widespread phenomenon of inbreeding depression. Evidence suggests that recessive deleterious mutations may be abundant in nature, likely due to their ability to persist for long timescales at moderate frequencies. It is thus possible that when an adaptive mutation occurs, it lands on a chromosome containing a recessive deleterious mutation. We propose a model for this and find that recessive deleterious mutations can significantly slow adaptation and alter signatures of adaptation.