Nutrient acquisition-related traits converge in Arcellinida (Lobosea, Amoebozoa) evolution

Recent works have demonstrated the importance of convergences in the evolutionary history of Arcellinida. Notably, test traits, traditionally used as diagnostic criteria in taxonomy, often present morphological convergences when species live in similar habitats. Understanding how strongly these characteristics are conserved within lineages or acquired independently is fundamental for interpreting Arcellinida evolution and for functional analyses in community ecology. This work focused on two well-characterised functional traits related to nutrient acquisition: aperture morphology (associated with large-prey hunting) and symbiosis with microalgae, and placed their occurrence in a phylogenetic context with the aid of a new COI primer designed for Arcellinida. In both cases, traits appeared to be labile across the trees, emphasizing the importance of convergence in Arcellinida evolution. These results call for a better assessment of trait conservatism in the group in order to use phylogenetic signals to improve our interpretation of environmental data.