Strategies for sustainable utilization and conservation of the Philippine carabao’s valuable genetic resource are informed by an understanding of the genetic architecture and relationship among various swamp buffalo populations.

Genetic conservation of diverse animal species, including the Philippine carabao, is one of the mandates of the DA-Philippine Carabao Center (DAPCC).

Conservation efforts are done in two ways: in-situ conservation of live animals in their natural habitat or in institutional herd and ex-situ cryoconservation of animal germplasm in the National Livestock Cryobank at DA-PCC.

So, what is then the genetic pattern of the Philippine carabao? And what is its genetic position in relation to neighboring countries?

Genetic pattern and relationship of the Philippine carabao

To approach this question, the DAPCC Animal Genetic Resources team analyzed the maternal information using 367 mitochondrial DNA (mtDNA) D-loop region variations from eight swamp buffaloes populations. These include the Philippines, China, Myanmar, Laos, Thailand, Vietnam, Taiwan, and Malaysia. This was a starting point to determine the degree of genetic relatedness and exchange among the selected Asian swamp buffalo populations.

The genetic differences based on maternal D-loop sequences among the swamp buffaloes from the major islands in the Philippines were attributed to the differences between individuals rather than among populations. This means that there is little population differentiation that existed mainly due to the Philippine carabao in Visayas and Mindanao. This genetic pattern indicates the prevalence of high genetic exchange of swamp buffaloes living in these sub-groups of major islands, with geographically close populations and had improved accessibility to interisland transportations. Meanwhile, the high genetic differentiation within Luzon indicated the swamp species’ restricted gene flow caused by the surrounding mountainous and coastal areas.

Thus, the pattern of genetic relationship of Philippine swamp buffalo populations could be influenced by the geographical features of the islands where they inhabit.

Genetic position of Philippine carabao in relation to neighboring countries

The phylogenetic or evolutionary relationship of the Philippine carabao showed two main clusters: the first cluster consisted mostly of the three major islands in the Philippines, Myanmar, and Taiwan, while the second cluster was found predominantly in mainland populations encompassing China, Malaysia, Laos, Thailand, and Vietnam.

In this study, the Philippine carabao had higher genetic diversity than Taiwan, Myanmar, and Malaysia. What does it mean? With the Philippine carabao’s high genetic diversity, it implies a lot of mutations in the DNA. The mutations cause differences in animal appearance and important traits. In addition, the variety of characteristics in Philippine carabao with high genetic diversity indicates that they are more likely to cope with changes in their environment successfully. The additional research findings by including more individuals from Asian regions like Cambodia and Indonesia would be needed to ensure that low population differentiation is not an artifact of sampling from the Asia populations.

Among the Philippines' major islands, there was a very low genetic variation detected between Visayas and Mindanao in the Philippines and Taiwan.

From this study, the Philippine swamp buffalo populations from the Visayas and Mindanao sub-group of major islands seemed to be closely related to Taiwan swamp buffaloes, whose genetic information were obtained from an old population in the conservation sites. This genetic pattern suggested an extensive level of gene flow among swamp buffalo populations. However, the high genetic exchange of swamp buffaloes between the two major islands of Visayas and Mindanao could be explained in two perspectives. First relates to the history of early migration of farmers who brought their native carabaos from Visayas to Mindanao for rice cultivation. Secondly, it is possible that access within and between inter-island transportation could have caused the genetic exchange of swamp buffaloes among sub-populations in the Philippines.

This study supported the results of genetic analysis showing lack of genetic differentiation between Visayas and Mindanao, suggesting that swamp buffaloes are introduced from Mindanao. Thus, the notion that the spread of domesticated Chinese swamp buffaloes from Taiwan to the Philippines could have been introduced to the Visayas rather than to Mindanao.

Thus, the results of this research agreed with the hypothesis of Lau et al. (1998) that after the domestication in the China region, the domesticated swamp buffalo spread to Taiwan, to the Philippines, then to the eastern islands of Borneo and Sulawesi.

Highlights of the research findings and implications

The research findings highlighted the genetic relationship among the modern Asian swamp buffalo populations. It can be deduced that the modern Philippine carabao population had the closest affinity to Taiwan swamp buffalo population based on the low genetic distance and that the Chinese swamp buffalo could be the ancestral population of the modern population of the swamp buffaloes in Asia, which was spread to Taiwan then introduced to the Visayas island of the Philippines, as supported by inferred mtDNA haplotypes.

Results imply that native buffaloes in the Philippines have various genes of buffaloes whose numbers are declining in Southeast Asian countries. This points to the importance of conserving and maintaining the Philippine carabao as a valuable resource while utilizing them in the Philippines.

Acknowledgement Full paper can be accessed on Genetic Divergence and Phylogenetic Relationship - ????... https://nodai.repo.nii.ac.jp › The research study was an extension work as part of the dissertation of LPVillamor and was conducted under the mentorship of Dr. Koh Nomura, Dr. Yukimizu Takahashi, and Dr.Takashi Amano in Tokyo University of Agriculture, Atsugi Campus, Japan through the Ph.D. by research Tokyo NODAI-SEARCA scholarship. A special thanks to the Philippine Carabao Center National Headquarters and Gene Pool (PCC-NHQGP) and the Department of Agriculture Livestock Biotech Program and the Bureau of Agricultural Research through the DABIOTECHR1506 project for the research funds.