The role of microbial interactions in the origin of animals

Microbial interactions were key to the origin of eukaryotes and may also have been important in transitions to multicellularity across the eukaryotic tree of life.

Today, in animals and a close unicellular relative, the choanoflagellates, bacteria can influence multicellular development.

It is thus suggested that microbial interactions were involved in the evolution of multicellular animals from a unicellular ancestor.

But to infer roles in the origin of animals, we need to investigate interactions across the remaining diversity of closest unicellular animal relatives, in which microbial interactions are unstudied.

We propose to fill this critical knowledge gap using single-cell metagenomics, transcriptomics, and phylogenetics to investigate across all major lineages of close unicellular animal relatives 1. which prokaryotes participate in interactions, 2. how microbial interactions affect multicellular behaviour and gene expression, and 3. how genes involved in interactions evolved and which genes were horizontally transferred from interaction partners.

Research will occur over three years with Prof. Iñaki Ruiz-Trillo, Assoc. Prof. Fabien Burki, and Prof.

Thomas Richards, experts in unicellular animal relatives, eukaryotic diversity, and microbial interactions in evolutionary transitions.

With the results we can reconstruct contributions from microbial interactions on the path from unicellular ancestor to animal, and gain insight into multicellular transitions.