The Philippine archipelago was believed to have never been connected to the Asian continent even during the severe Quaternary sea-level drops. As a result, the history of domestic pig (Sus scrofa) dispersal in the Philippines remains controversial and must have some anthropogenic origin associated with human migration events. In this study, the context of origin, dispersal, and the level of genetic introgression in Philippine domestic pigs were deduced using mitochondrial DNA D-loop analysis altogether with domestic pigs and wild boar corresponding to their geographic origin. The results revealed considerable genetic diversity (0.900±0.016) and widespread Asian pig-ancestry (94.60%) in the phylogenetic analysis, with admixed European pig-origin (5.10%) harboring various fractions of ancestry from Berkshire and Landrace. The close genetic connection between the continental wild boars and domestic pigs present in the Philippine domestic pigs corroborates our hypothesis of a genetic signal that may be associated with the recently reported multiple waves of human migrations to the Philippines. The Haplogroup D7, reported to occur only in Indo-Burma Biodiversity Hotspots, included a high frequency of Philippine domestic pig haplotypes (54.08%), which poses an interesting challenge because its distribution is not consistent with the hypothesized migration route of Neolithic Austronesian-speaking populations. We detected the first Pacific Clade signature and ubiquitously distributed D2 haplotypes (Asian major) on several Philippine islands. The analyses of mismatch distribution and neutrality test were consistent with the Bayesian skyline plot which showed a long stationary period of effective population size. The population decline was consistent with the pronounced population bottleneck in Asian and European pigs during the interglacial periods of the Pleistocene. The results of this study will support the conservation strategies and improvements of economically important genetic resources in the Philippines.

This study assessed the morphological characteristics of the native pig population in Bohol Island, Philippines. A total of 100 sexually-mature native pigs (80% gilt/sow and 20% barrow/boar) were selected from the municipalities of Balilihan, Bilar, Talibon, Ubay, Loon, Guindulman, Mabini, San Miguel, Pilar, and Alburquerque, which are densely populated with native pigs (based on the data of the Office of the Provincial Veterinarian-Bohol). Purposive sampling was used to select the experimental pigs based on the phenotypic traits that qualify them as native. Likewise, remote barangays where native pigs are most likely raised were selected as sample sites. The qualitative (hair color, color pattern, and ear orientation) and quantitative (tail length, teat number, estimated body weight using body length, and heart girth measurements) traits were recorded based on subjective observation and actual measurements, respectively. Qualitatively, the native pigs in Bohol have predominantly (73%) black hair. In terms of color pattern, plain color (91%), spotted (4%), and patchy (5%) were noted. The native pigs also revealed droopy (54%), slightly droopy (37%), and erect (9%) ear orientations. Meanwhile, quantitative traits revealed an overall body length of 38.07 ± 8.75 inches, heart girth of 36.9 ± 8.83 inches, body weight of 67.29 ± 41.15 kg, tail length of 9.78 ± 2.45 inches, and 12.38 ± 1.33number of teats. Significant differences across sampling areas(p<0.05)and sex (p<0.01) were observed. Generally, females had higher values than males, and there was a significant difference (p<0.05) in trait values among age groups.