Abstract

Summary The opisthokonts are one of the major super groups of eukaryotes. It comprises two major clades: (i) the M etazoa and their unicellular relatives and (ii) the F ungi and their unicellular relatives. There is, however, little knowledge of the role of opisthokont microbes in many natural environments, especially among non-metazoan and non-fungal opisthokonts. Here, we begin to address this gap by analysing high-throughput 18 S rDNA and 18 S rRNA sequencing data from different European coastal sites, sampled at different size fractions and depths. In particular, we analyse the diversity and abundance of choanoflagellates, filastereans, ichthyosporeans, nucleariids, corallochytreans and their related lineages. Our results show the great diversity of choanoflagellates in coastal waters as well as a relevant representation of the ichthyosporeans and the uncultured marine opisthokonts ( MAOP ). Furthermore, we describe a new lineage of marine fonticulids ( MAFO ) that appears to be abundant in sediments. Taken together, our work points to a greater potential ecological role for unicellular opisthokonts than previously appreciated in marine environments, both in water column and sediments, and also provides evidence of novel opisthokont phylogenetic lineages. This study highlights the importance of high-throughput sequencing approaches to unravel the diversity and distribution of both known and novel eukaryotic lineages.

Javier del Campo

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

Ramon Massana

Staff scientist

I am microbial ecologists with a deep interest in protist ecology and evolution