Mitochondrial genomes of domestic animals need scrutiny.

More than 1000 complete or near-complete mitochondrial DNA (mtDNA) sequences have been deposited in GenBank for eight common domestic animals (cattle, dog, goat, horse, pig, sheep, yak and chicken) and their close wild ancestors or relatives, as well. Nevertheless, few efforts have been performed to evaluate the sequence data quality. Herein, we conducted a phylogenetic survey of these complete or near-complete mtDNA sequences based on mtDNA haplogroup trees for the eight animals. We show that errors due to artificial recombination, surplus of mutations and phantom mutations do exist in 14.5% (194/1342) of mtDNA sequences and all of them should be treated with wide caution. We propose some caveats for future mtDNA studies of domestic animals.