The oceanographic isolation of the Ogasawara Islands and genetic divergence in a reef-building coral

Aim: Due to their spatial isolation, oceanic islands are natural systems to study evolutionary divergence. The Ogasawara Islands belong to the most isolated archipelagos on Earth and are well-known for their high terrestrial endemicity, however, less is known about the marine realm. Here, we analyze the degree of oceanographic isolation of the archipelago based on genetic data of a reef-building coral and a biophysical dispersal model.
Location: North-Western Pacific (Ogasawara, Ryukyu, Daito Islands, Guam)
Taxon: Galaxea fascicularis L.
Method: Three to 15 specimens were sampled at several sites in Ogasawara and its closest potential migration sources in southern Japan and the Mariana Islands (Guam) and RAD-sequenced. 108 specimens from the common Pacific lineages ‘L’ (Ryukyu- and Daito Islands, Guam) and ‘Ogasawara’ (Ogasawara) were analyzed with population genetics and demographic modeling. Oceanographic dispersal was investigated by inverse particle tracking using a Lagrangian parti...