Deconstructing Difflugia: The tangled evolution of lobose testate amoebae shells (Amoebozoa: Arcellinida) illustrates the importance of convergent evolution in protist phylogeny

• Published in: Molecular phylogenetics and evolution 2022-10, Vol.175, p.107557-107557, Article 107557
• Main Authors: González-Miguéns, Rubén, Todorov, Milcho, Blandenier, Quentin, Duckert, Clément, Porfirio-Sousa, Alfredo L., Ribeiro, Giulia M., Ramos, Diana, Lahr, Daniel J.G., Buckley, David, Lara, Enrique
• Format: Article
• Language: English
• Subjects: Arcellinida; Convergent evolution; genes; lead; mitochondria; Mitochondrial editing; Phylomorphospace; polyphyly; protists; Tangled evolution; Testate amoeba
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1016/j.ympev.2022.107557

[Display omitted] •A taxon-rich, three genes approach improves phylogenetic reconstruction of Arcellinida.•New infraorder Cylindrothecina and two genera Cylindrifflugia and Golemanskia.•We characterise mitochondrial mRNA editing in Arcellinida.•We show convergent evolution in Arcellinida shells.•We refute the paradigm of “morphological stasis” for Arcellinida evolution. Protists, the micro-eukaryotes that are neither plants, animals nor fungi build up the greatest part of eukaryotic diversity on Earth. Yet, their evolutionary histories and patterns are still mostly ignored, and their complexity overlooked. Protists are often assumed to keep stable morphologies for long periods of time (morphological stasis). In this work, we test this paradigm taking Arcellinida testate amoebae as a model. We build a taxon-rich phylogeny based on two mitochondrial (COI and NADH) and one nuclear (SSU) gene, and reconstruct morphological evolution among clades. In addition, we prove the existence of mitochondrial mRNA editing for the COI gene. The trees show a lack of conservatism of shell outlines within the main clades, as well as a widespread occurrence of morphological convergences between far-related taxa. Our results refute, therefore, a widespread morphological stasis, which may be an artefact resulting from low taxon coverage. As a corollary, we also revise the groups systematics, notably by emending the large and highly polyphyletic genus Difflugia. These results lead, amongst others, to the erection of a new infraorder Cylindrothecina, as well as two new genera Cylindrifflugia and Golemanskia.