PlankDiv · Diversification of the Eukaryotic Plankton in the Sunlit Ocean

Oceanic plankton constitute a diverse array of organisms crucial to Earth’s carbon cycle, climate regulation, and the functioning of the ecosystems. A key biological challenge lies in understanding the build-up of planktonic diversity in the global oceans. Two primary limitations are the scarcity of robust (phylo)genetic data for most plankton groups, and the lack of computational tools designed to explore diversification in the ocean, continually shaped by currents. Here, I propose to characterize the patterns and drivers of diversification across present-day eukaryote plankton groups by harnessing three main resources: i) recent global-scale surveys of oceanic samples, ii) emerging long-read metabarcoding technologies, and iii) my team’s expertise in developing innovative modeling tools.First, we will generate long-read metabarcoding data for over 800 plankton samples worldwide. We will characterize the diversity and distribution of major eukaryotic plankton groups above and below the species level. Second, we will develop an evolutionary model in the global open ocean, providing predictions on the mode and tempo of diversification. We will evaluate the role of current-mediated dispersal constraints and environmental selection in driving genetic differentiation and speciation. Third, we will construct taxonomically rich phylogenetic trees for the major eukaryotic plankton groups and analyze variations in diversification rates through time and across oceans. Fourth, we will reconstruct paleo-oceans throughout the Cenozoic era and elucidate how past environmental changes have influenced diversification dynamics. This proposal represents the first endeavor to conduct a comparative analysis of diversification across eukaryote plankton groups, from microevolutionary to macroevolutionary scales. The results will provide a comprehensive understanding of the mechanisms underpinning diversity patterns in the global oceans.