Mitochondrial DNA sequence variation and phylogenetic relationships among Iberian pigs and other domestic and wild pig populations.

Nucleotide sequences of mitochondrial DNA (mtDNA) cytochrome B gene (1140 bp) and control region (707 bp) were used to determine the phylogenetic relationships among 51 pig samples representing ancient and current varieties of Iberian pigs (26), Spanish wild boars (seven) and other domestic pigs (18) of cosmopolitan (Duroc, Large White, Landrace, Pietrain and Meishan) and local (Spotted Black Jabugo, Basque and Mangalitza) breeds. A neighbour-joining tree constructed from pairwise distances provide evidence of the European origin of both Iberian pigs and Spanish wild boars. The introgression of Asian mtDNA haplotypes in the genetic pool of the Iberian breed seems unlikely. Four estimates of sequence divergence between European and Asian clades were calculated from the two main domains of the D-loop region and the synonymous and nonsynonymous nucleotide substitutions in the cytochrome B gene. The time since the divergence of pig ancestors was estimated at about 600,000 years before present.