Figure: Depiction of the tree of life including DPANN
From deep time to real-time

This grant provides Spang with the opportunity to push her research to the next level. Spang: ‘I am extremely honoured to be one of the recipients of this grant. It allows me to delve into the mysterious world of archaeal symbionts.’ She now turns to the so-called DPANN Archaea, a very diverse group of symbiotic microorganisms that occur almost everywhere on Earth. Spang: ‘I suspect that the genomes of these symbionts hold important insights into the early evolution of cellular life.’ On the one hand, she will analyse genetic material to reconstruct the evolution of these organisms through deep time. On the other hand, Spang intends to use experimental approaches to investigate the evolution of symbiotic Archaea in real-time. Spang: ‘For the first time we will combine both macro- and microevolutionary approaches.

Possible discovery of important player in food web dynamics 

Besides playing an important role in early evolution, Spang suspects that DPANN Archaea have a much bigger impact on other organisms than has been assumed so far. Spang: ‘Many of these symbionts have limited metabolic capabilities and resemble viruses in that they need a host for survival. One may wonder if we missed a component in food webs that operates besides viruses and predators.’ ​​​​This would have implications for the (re-)cycling of organic matter in the environment as well as eco-evolutionary dynamics.

To better understand the symbiont-host interaction, Spang intends to take on an experimental approach and study cultivated DPANN in co-culture with their hosts and track their evolution through time. Outside the lab, the impact of DPANN populations and their impact on host organisms will be assessed in their natural environment. Spang: ‘ASymbEL could provide key insights into the global impact of these symbionts in the deep origins and diversification of cellular life on Earth. It paves the way for a deeper understanding of symbiotic evolutionary theory and the fundamental laws of cellular evolution.’

Sampling campaign on the Black Sea in summer 2018. Photo: Nina Dombrowski