What Can Environmental Sequences Tell Us About the Distribution of Low-Rank Taxa? The Case of Euplotes (Ciliophora, Spirotrichea), Including a Description of Euplotes enigma sp. nov.

Abstract

Environmental sequences have become a major source of information. High-throughput sequencing (HTS) surveys have been used to infer biogeographic patterns and distribution of broad taxa of protists. This approach is, however, more questionable for addressing low-rank taxa such as species and genera, because of the increased chance of errors in identification due to blurry taxonomic boundaries, low sequence divergence, or sequencing errors. The specious ciliate genus Euplotes partially escapes these limitations. It is a ubiquitous, monophyletic taxon, clearly differentiated from related genera, and with a relatively well-developed internal systematics. We present an update on Euplotes biogeography, taking into consideration for the first time environmental sequences, both traditional (Sanger) and HTS. We inferred a comprehensive small subunit rRNA gene phylogeny of the genus including a newly described marine species, Euplotes enigma, characterized by a unique question mark-shaped macronucleus. The resulting scenario conflicts on many accounts with previously held views, suggesting that a large diversity of anaerobic Euplotes species exist, and that marine representatives of mainly freshwater lineages (and vice-versa) might be more common than previously thought.

Javier del Campo

Group Leader

My research aims at understanding the global diversity and distribution of eukaryotic and prokaryotic microbes employing curated phylogenetic frameworks focusing on novel environmental taxa.