Phylogeography of the seaweed Ishige okamurae (Phaeophyceae): evidence for glacial refugia in the northwest Pacific region
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Although benthic marine algae are essential components of marine coastal systems that have been influenced profoundly by past and present climate change, our knowledge of seaweed phylogeography is limited. The brown alga Ishige okamurae Yendo occurs in the northwest Pacific, where it occupies a characteristic belt in the exposed intertidal zone. To understand the patterns of genetic diversity and the evolutionary history of this species, we analyzed mitochondrial cox3 from 14 populations (221 individuals) throughout its range. The 17 haplotypes found in this study formed five distinct clades, indicating significant genetic structure. The high differentiation and number of unique (private) haplotypes may result from the recolonization of the species from glacial refugia. Three putative refugia, each with high genetic diversity, were identified: southern Korea (including Jeju Island), northern Taiwan, and central Pacific Japan. Recolonization of I. okamurae was probably determined by ocean currents and changes in sea level during the last glacial period.
KeywordsKuroshio Current Mismatch Distribution Glacial Refugium Benthic Marine Alga Oceanographic Regime
This study was supported by a Korean Research Foundation (KRF) grant (MEST; 2009-0077972) and a grant from Marine Biotechnology Program funded by Ministry of Land, Transport, and Maritime Affairs of Korean government. We thank Gong Soo Chung, Youn Ho Lee, Dong Jin Lee, and Min Hur for their useful advice on paleogeography of the Korean peninsula, Paul John Geraldino and Ga Hun Boo for collections from Japan, and Put O. Ang, and Song Qin and Yang Rui for help in collections in Hong Kong and China, respectively.
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