Zoantharians Break the Rules of Marine Biogeography With Weak Ocean-Basin

Zoantharians, an order of cnidarians related to stony corals, appear to break a long-standing biogeography expectation: Atlantic and Indo-Pacific populations show surprisingly weak genetic differentiation, according to the first comprehensive global assessment of their distribution. The study, published in Frontiers of Biogeography, contrasts with reef fishes and stony corals, where the Indo-Pacific typically has several times more diversity than the Atlantic at family and genus levels. Researchers combined literature reviews with snorkeling and SCUBA surveys at 0 to 40 meters across sites including Yucatan, Hong Kong, Cebu, South Africa, Bali and Taiwan, plus DNA and morphology from museum specimens. They found some genera are broadly cosmopolitan and also identified sibling species complexes spanning both basins.