Patterns of Genetic Differentiation Among the Small Population of Animals in the Philippines: A Synthesis Review

Abstract.This synthesis review examined common patterns on genetic differences of the small or isolated populations of animals in the Philippines. It reviewed ten (10) published articles from 2020 to 2025 focusing on genetic differences of these species including mosquitoes (Aedes aegypti), marine species (sea cucumbers, giant trevallies, white teatfish), terrestrial mammals (Visayan spotted deer, Eonycteris robusta), freshwater fish (Glossogobius aureus), and livestock (Philippine native pigs, chickens, and carabao). Using a thematic synthesis approach, the results showed the following common themes: 1) genetic diversity of isolated populations; 2) geographic isolation and population structure; 3) adaptive divergence and local selection; 4) human-mediated influence of genetic differentiation; and 5) conservation, management, and biodiversity implications. Thus, this review showed that genetic diversity was uneven, population structure was strong, adaptive divergence occurred even in separated habitats, and human activities strengthened genetic differentiation. These findings had important implications for conservation, resource management, and biodiversity sustainability in the Philippines. Keywords: Genetic Diversity; Isolated Populations; Population Structure; Geographic Isolation; Adaptive Divergence; Conservation and Management