Deleterious mutations at the mitochondrial ND3 gene in South American marsh rats (Holochilus).
Statistical analyses of DNA sequences have revealed patterns of nonneutral evolution in mitochondrial DNA of mice, humans, and Drosophila. Here we report patterns of mitochondrial sequence evolution in South American marsh rats (genus Holochilus). We sequenced the complete mitochondrial ND3 gene in 82 Holochilus brasiliensis and 21 H. vulpinus to test the neutral prediction that the ratio of nonsynonymous to synonymous nucleotide changes is the same within and between species. Within H. brasiliensis we observed a greater number of amino acid polymorphisms than expected based on interspecific comparisons. This contingency table analysis suggests that many amino acid polymorphisms are mildly deleterious. Several tests of the frequency distribution also revealed departures from a neutral, equilibrium model, and these departures were observed for both nonsynonymous and synonymous sites. In general, an excess of rare sites was observed, consistent with either a recent selective sweep or with populations not at mutation-drift equilibrium.
Kennedy
P
P
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA. pkennedy@u.arizona.edu
Nachman
M W
MW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics*; D042967:Electron Transport Complex I; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009154:Mutation; D011110:Polymorphism, Genetic; D011506:Proteins / Q000235:genetics*; D012377:Rodentia / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D004272:DNA, Mitochondrial; D011506:Proteins; D042967:Electron Transport Complex I; C114961:MT-ND3 protein, human