2024/07/31 by Iris Rizos, Miguel J. Frada, Lucie Bittner +1 · 1 voice
Biochemistry, Genetics and Molecular Biology · Environmental Science · #Protist diversity and phylogeny #Microbial Community Ecology and Physiology #Environmental DNA in Biodiversity Studies
paper · pdf · doi:10.1111/jeu.13052
openalex publication_date 2024/07/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
An astonishing range of morphologies and life strategies has arisen across the vast diversity of protists, allowing them to thrive in most environments. In model protists, like Tetrahymena, Dictyostelium, or Trypanosoma, life cycles involving multiple life stages with different morphologies have been well characterized. In contrast, knowledge of the life cycles of free-living protists, which primarily consist of uncultivated environmental lineages, remains largely fragmentary. Various life stages and lineage-specific cellular innovations have been observed in the field for uncultivated protists, but such innovations generally lack functional characterization and have unknown physiological and ecological roles. In the actual state of knowledge, evidence of sexual processes is confirmed for 20% of free-living protist lineages. Nevertheless, at the onset of eukaryotic diversification, common molecular trends emerged to promote genetic recombination, establishing sex as an inherent feature of protists. Here, we review protist life cycles from the viewpoint of life cycle transitions and genetics across major eukaryotic lineages. We focus on the scarcely observed sexual cycle of free-living protists, summarizing evidence for its existence and describing key genes governing its progression, as well as, current methods for studying the genetics of sexual cycles in both cultivable and uncultivated protist groups.