Abstract

The Antarctic marine environment has a unique geologic and climatic history that has contributed to the evolution of highspecies diversity. Given the current trend of environmental warming, understanding the history of Antarctic species is crucialfor predicting the impact of climate change on ecosystem function. Soft corals are a group of striking presence in the benthicmarine assemblages in the Southern Ocean, which is recognized as a biodiversity hotspot. DNA sequences (Cox1, mtMutS, and28S rDNA) were utilized for molecular phylogenetic reconstructions, species delimitations, and divergence estimations to inves-tigate the spatial patterns of genetic diversity in Alcyonium species in the southern South American-Antarctic region. Significantgenetic divergence was observed between regions, with a clear genetic break between South America and the West AntarcticPeninsula and the identification of four putative species. Divergence time estimates indicated that Alcyonium's diversificationbegan about 41.1 million years ago (Ma), coinciding with the opening of the Drake Passage and the formation of the AntarcticCircumpolar Current (ACC, ~42 Ma). This indicates that Alcyonium has persisted in situ for an extensive period, enduring a widerange of environmental condition