Evolution of a morphological novelty occurred before genome compaction in a lineage of extreme parasites

Abstract

Significance Intracellular obligate parasitism results in extreme adaptations, whose evolutionary history is difficult to understand, because intermediate forms are hardly ever found. Microsporidia are highly derived intracellular parasites that are related to fungi. We describe the evolutionary history of a new microsporidian parasite found in the hindgut epithelium of the crustacean Daphnia and conclude that the new species has retained ancestral features that were lost in other microsporidia, whose hallmarks are the evolution of a unique infection apparatus, extreme genome reduction, and loss of mitochondrial respiration. The first evolutionary steps leading to the extreme metabolic and genomic simplification of microsporidia involved the adoption of a parasitic lifestyle, the development of a specialized infection apparatus, and the loss of diverse regulatory proteins.

High-level classification of the Fungi and a tool for evolutionary ecological analyses

“…We prefer the name Rozellomycota over Cryptomycota, because (1) the phylum-level taxon Rozellida was described before Cryptomycota and (2) Rozellida hints to the type Rozella, whereas Cryptomycota hints to Cryptomyces, which is an ascomycete. Recent phylogenies indicate that Microsporidia are deeply nested within Rozellomycota (Corsaro et al 2014;Haag et al 2014;Keeling et al 2014;. To keep Rozellomycota a single monophyletic phylum, we consider microsporidians at the class (Microsporidea) level within this group.…”

Diversity and origins of anaerobic metabolism in mitochondria and related organelles

“…Two newly discovered deep-branching relatives of microsporidians, Rozella and Mitosporidium, have recently been shown to have more complex MROs compared with previously studied microsporidia (e.g. they each have mitochondrial DNA, a Krebs cycle, complexes II-IV of the ETC and an ATP synthase [55,68]). …”

Cucumispora ornata n. sp. (Fungi: Microsporidia) infecting invasive ‘demon shrimp’ (Dikerogammarus haemobaphes) in the United Kingdom

“…Rozella spp.) and 63 the Microsporidia (Haag et al 2014). Novel taxonomic descriptions now combine data 64 pertaining to ultrastructural features, lifecycle characteristics, host type and habitat type, and 65 conclusively, phylogenetics (Stentiford et al 2013b).…”