Over the millennia, perpetual geological sea level changes have continuously shaped coral reef environments. Coral reef biodiversity, considered at its peak within the Coral Triangle, is most notable throughout the Philippine archipelago largely due to it having among the highest number of islands (more than 7,100) per geographical area. The origin of such diversity remains the subject of much controversy and investigation generating hypotheses of speciation and migration from within or outside the region. Nevertheless, central to determining reef biodiversity and biogeographical distributions are species responses to environmental change, particularly as human impacts accelerate and/or exacerbate natural processes.