Phylogeny and Genetic Diversity of Philippine Native Pigs (Sus scrofa) as Revealed by Mitochondrial DNA Analysis

Abstract

Philippine native pigs (PhNP) are small black pigs domesticated in rural communities in the Philippines. They are valued locally for their various sociocultural roles. Recently, considerable literature has accumulated in the field of native pig production and marketing. However, there is limited research on the genetic diversity of PhNP. No previous study has investigated the evolutionary relatedness among native pigs from various islands and provinces in Luzon and Visayas, Philippines. In addition, a much-debated question is whether the PhNP were interbreeding with or even domesticated from endemic wild pigs. This study aims to clarify some of the uncertainties surrounding the identity and classification of PhNP based on mitochondrial DNA (mtDNA) signatures. Native pig samples (n=157) were collected from 10 provinces in Luzon and the Visayas, Philippines. Approximately 650 base pairs of the mtDNA d-loop control region were sequenced and analyzed together with publicly available sequences. Pairwise-distance analysis showed genetic separation of North and South Luzon (SL) and the clustering of SL with Visayan pigs. Phylogenetic analysis showed that the PhNP clustered within 3 recognized Asian pig domestication centers: D2 (East Asia), D7 (Southeast Asia) and the Cordillera clade (sister to the Lanyu). We identified 19 haplotypes (1-38 samples each), forming 4 haplogroups i.e. North Luzon, South Luzon and Visayas, Asian mix and the Cordillera cluster. No endemic wild pig mtDNA was detected in the native pig population, but the use of wild pig for interspecific hybridization was observed. This study showed that the Philippine native pigs have ancestral origin from at least 3 Sus scrofa lineage and that they were not domesticated from the endemic wild pigs of the Philippines.