The late Quaternary glacial oscillations and associated tectonic processes (e.g. topological and structural configurations of habitats) are increasingly believed to have greatly influenced the tempo-spatial adpative evolutionary dynamics and biodiversity gradients of terrestrial organisms in the Northern Hemisphere. In the marine ecosystems, however, accumulating evidence indicated that factors shaping population genetic variations and distribution patterns of marine taxa vary considerably with either distinct biological features (e.g. larval stage and drifting dispersal capability) or environmental forces including biogeographical latitude and complex hydrogeological dynamics (e.g. diverse oceanic current systems and no dispersal barrier among marine regimes). Deciphering how these factors contributed to range shifts of population genetic connectivity and molecular phylogeographic architecthures can largely promote our understanding on speciation, adaptation and diversification of marine organisms drove by selective forces, whether historically or contemporarily, from both ecological and evolutionary perspectives. In this project we will focus on four typical Sargassum species (S. thunbergii, S. fusiforme, S. pallidum and S. polycystum) in the Asia-Northwest Pacific with each harboring distinct biological characteristics, through approaching the combined analyses of coalescent population genetics and geographic information system (GIS)-based ecological niche modeling. Our main objectives are as follows: 1) comprehensively investigate the geographical patterns of genetic variation of Sargassum species in the Asia-Northwest Pacific from both evolutionary and ecological timescales, and then reveal the deep tempo-spatial profiles of genetic affinity and evolutionary processes based on the integration of molecular, ecological, geographical and paleoenvironmental data sets; 2) explore the potential influential mechanisms of ice age, oceanic circulation and biological features on geographic distribution of Sargassum species, extrapolate some cryptic glacial refugia in the Asia-Northwest Pacific coastlines, and probe the corresponding influence of climatic, environmental and biological factors respectively on the biodiversity of seaweed species, and the even mutural interactions between each factor. The implement of this project can provide significant theoretical and practical insights for discovery and conservation of genetically important marine biological resources, and even monitoring coastal environmental ecosystems.