[Science news] - Seaweeds

Seaweeds indicate origins of Coral Triangle biodiversity



The Coral Triangle is a tropical marine area spanning Indonesia, Malaysia, the Philippines and Papua New Guinea. It has incredible biodiversity, including 75% of all coral species, more reef fish species than anywhere else, and the world’s largest mangrove forests. Scientists are still debating the reasons for this area’s extreme biodiversity.

Researchers at Meise Botanic Garden study marine as well as land plants. Working with an international team, they recently investigated how a genus of a red seaweed, Portieria, evolved over the region.

The team analysed DNA sequences from over 800 samples of Portieria from across the Indian and Pacific Oceans. Portieria species look alike, but genetic analysis revealed high diversity – much larger than expected, and that those in the Coral Triangle are the most diverse.

Phylogenetic analyses indicate that Portieria originated during the late Cretaceous (ca. 100 million years ago). It likely arose in the area that is now the Central Indo‐Pacific, then spread via dispersal and tectonic movement. New locations, and the fact that Portieria does not disperse well in open water, allowed species to diversify at small spatial scales.

The study [https://doi.org/10.1111/jbi.13410] published in the Journal of Biogeography concludes that for Portieria, the Coral Triangle biodiversity hotspot acts as both a ‘centre of origin’ and a ‘centre of accumulation’, corroborating previous findings for invertebrates and fish that there is no single model explaining biodiversity in the region.