Copepod functional traits and groups show contrasting biogeographies in the global ocean

Aim To define global zooplankton functional groups (FGs) and to estimate their environmental niche and habitat distribution. We model the spatial patterns of copepod FGs habitat and identify regions sharing similar functional trait expression at the community level. Taxon Marine planktonic Neocopepoda. Location Global ocean. Methods Factor analysis on mixed data and hierarchical clustering were used to identify copepod FGs based on five species-level functional traits. An ensemble of species distribution models was used to estimate the environmental niches of the modelled species, project the mean annual habitat suitability of the FGs, and to estimate the community weighted mean values of the traits studied. Ocean regions were defined based on their community-level mean trait expression using a principal component analysis and hierarchical clustering. Results Eleven global copepod FGs were identified. They displayed contrasting latitudinal patterns in mean annual habitat suitability that could be explained by differences in environmental niche preferences: two FGs were associated with polar conditions, one followed the global temperature gradient, five were associated with tropical oligotrophic gyres, and the remaining three with boundary currents and counter currents. Four main regions of varying community weighted mean trait values emerged: the Southern Ocean, the northern and southern high latitudes, the tropical gyres, and the boundary currents and upwelling systems. Conclusions We build on an exhaustive species trait dataset to put forward novel FGs that will improve the representation of zooplankton in global marine ecosystem models. Our results contribute to our understanding of the spatial patterns and drivers of marine plankton trait biogeography and will serve as a basis for studying the links between zooplankton biodiversity and ecosystem functioning and how they might evolve in the context of climate change. ### Competing Interest Statement The authors have declared no competing interest.