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[Keynote presentation] Patterns and drivers of seaweed biodiversity

Research output: Chapter in Book/Report/Conference proceedingC3: Conference Abstract

Understanding the biogeographical processes underlying current biodiversity patterns is a central goal in ecology and evolutionary biology. We gain important insights in the evolutionary processes generating seaweed biodiversity patterns in two widespread clades, the red algal genus Portieria and the brown algal order Dictyotales, by applying DNA-based species delimitation methods, phylogenetic analyses, and probabilistic modelling of geographic range evolution. A first striking outcome of was that species diversity in the two clades is far greater than assumed based on formally described taxa. Although cryptic diversity is no exception in the marine environment, the degree of cryptic diversity found in Portieria and some genera of Dictyotales (e.g. Lobophora) is remarkable. Although a wide variation in species ranges was found, many species have restricted distributions, indicating overall low dispersal capacity. A clear pattern of high diversity was found in the tropical central Indo-Pacific, with declining diversity when moving away longitudinally as well as latitudinally from this region. Time calibrated phylogenetic analyses indicate that the two clades are ancient (late Cretaceous to middle Jurassic) and likely originated in the region that is now the central Indo-Pacific. We find general support for a higher diversification rate in tropical regions, in particular the central Indo-Pacific, and repeated dispersal events to peripheral regions. In the Dictyotales, two large clades, Dictyota and Lobophora, experienced a major burst of diversification in the central Indo-Pacific in the Paleocene, followed by dispersal outward. While Lobophora diversified strictly in tropical regions, Dictyota also expanded towards temperate regions. Our analyses show that given the old age of the clades involved, and the large diversity of organisms with different traits, different mechanisms produced biogeographical patterns in seaweeds. Finally, our study shows once more that accurate delimitation of species is important for understanding of distributions and diversification of tropical seaweeds.
Original languageEnglish
Title of host publication7th European Phycological Congress
Publication date2019
Publication statusPublished - 2019
Event7th European Phycological Congress - Zagreb, Croatia
Duration: 25-Aug-201930-Aug-2019
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