An integrative approach to phylogeny reveals patterns of environmental distribution and novel evolutionary relationships in a major group of ciliates

Abstract

Peritrichs are a major group of ciliates with worldwide distribution. Yet, its internal phylogeny remains unresolved owing to limited sampling. Additionally, ecological distributions of peritrichs are poorly known. We performed substantially expanded phylogenetic analyses of peritrichs that incorporated SSU rDNA sequences of samples collected from three continents, revealing a number of new relationships between and within major lineages that greatly challenged the classic view of the group. Interrogation of a dataset comprising new environmental sequences from an estuary and the open ocean generated with high throughput sequencing and clone libraries plus putative environmental peritrich sequences at Genbank, produced a comprehensive tree of peritrichs from a variety of habitats and revealed unique ecological distribution patterns of several lineages for the first time. Also, evidence of adaptation to extreme environments in the Astylozoidae clade greatly broadened the phylogenetic range of peritrichs capable of living in extreme environments. Reconstruction of ancestral states revealed that peritrichs may have transitioned repeatedly from freshwater to brackish/marine/hypersaline environments. This work establishes a phylogenetic framework for more mature investigations of peritrichs in the future, and the approach used here provides a model of how to elucidate evolution in the context of ecological niches in any lineage of microbial eukaryotes.

Phylogenomics solves a long-standing evolutionary puzzle in the ciliate world: The subclass Peritrichia is monophyletic

“…A fairly consistent relationship, when using the 18S rRNA, is that of Peniculia as sister to Mobilida (Sun et al, 2016;Utz and Eizirik, 2007;Zhan et al, 2009). In the phylogenomic analysis of Feng et al (2015), Paramecium, the only member of the Peniculia grouped as the sister taxon to the Peritrichia with strong support.…”

Morphology and Phylogeny of Three Pseudovorticella Species (Ciliophora: Peritrichia) from Brackish Waters of China

“…As the number of Pseudovorticella sequences increases, its relationship with Vorticella species is more robust while maintaining a very close relationship with Epicarchesium , which always nested within the Pseudovorticella clade (Sun et al. ). More sequences of SSU rDNA and other gene markers of Pseudovorticella are needed in order to disclose the relationships within the genus and among the related genera.…”

Morphology and Phylogeny of Four New Vorticella Species (Ciliophora: Peritrichia) from Coastal Waters of Southern China

“…Among the genera of Vorticellidae, Vorticella Linnaeus, 1767, Pseudovorticella Foissner and Schiffmann, 1974, and Epicarchesium Jankowski, 1985 were reported to be nonmonophyletic (Sun et al. ).…”

“…Etymology: The Greek word para (similar, near) indicates that the type population is similar to Vorticella chiangi Sun et al., .…”