Was the Lanyu pig independently domesticated in the Philippines? A meta-analysis review on the prehistoric expansion of the unique Lanyu pigs

Abstract

Due to the paucity of molecular studies, the origin of the unique Lanyu pigs has been described as “cryptic.” Recent evidence of the presence of Lanyu pigs with Type I signatures spanning from Northern Luzon (NL) through the western and central Philippine regions suggests the possibility of independent domestication of Lanyu pigs in the Philippines. To clarify the spatio-temporal dispersal of Lanyu pigs, this study meta-analyzed all D-loop sequences of Lanyu pigs with Type I signatures (n=323) from Taiwan and the Philippines and elucidated the role of humans in their expansion. The result supported the existence of two subclades of Type I Lanyu pigs, the Taiwanese Lanyu and the Philippine Lanyu subclades. While the two subclades shared certain morphological traits, the latter had signs of morphological patterns that had undergone feralization. Long-distance movement of these pigs during the post-Neolithic era may have been facilitated by the known back-and-forth migration between the islanders of Lanyu (Orchid Island) and the Batanes Archipelago, the northernmost region of the Philippines. Due to the absence of Lanyu pig signatures in Borneo and the fascinating presence of Lanyu signatures in Palawan, two possible scenarios are being proposed. First, the Lanyu pig originated in Taiwan and was introduced by humans (e.g., through trade after domestication into the Philippines) moving to the west of the Philippines where a new population later became established. Secondly, the ancestral origin of the Lanyu pig radiated from mainland Southeast Asia into the Philippines but was extirpated, leaving the subsequent population. The latter suggests the allopatric expansion of the unique Lanyu pigs, which could likely support that Sus scrofa is native to the Philippines. This finding provides new perspectives on the complex evolutionary and anthropogenic history of pig dispersal into Island Southeast Asia.