Untangling eco-evolutionary impacts on diatom genomes over timescales relevant to current climate change

ended

Diatoms are major contributors of primary production in the ocean and participate in carbon sequestration over geologically relevant timescales. As key components of the Earth’s carbon cycle and marine food webs we need to understand the eco-evolutionary underpinnings of their ecological success to forecast their fate in a future ocean impacted by anthropogenic change. Genomes and epigenomes from model diatoms, as well as hundreds of transcriptomes from multiple species, have revealed genetic and epigenetic processes regulating gene expression in response to changing environments. The Tara Oceans survey has in parallel generated resources to explore diatom abundance, diversity and gene expression in the world’s ocean in widely contrasting conditions. DIATOMIC will build on these resources to understand how evolutionary and ecological processes combine to influence diatom adaptations to their environment at unprecedented spatiotemporal scales. To examine these processes over timescales relevant to current climate change, DIATOMIC includes the pioneering exploration of ancient diatom DNA from the sub-seafloor to reveal the genetic and epigenetic bases of speciation and adaptation that have impacted their ecological success during the last 100,000 years, when Earth experienced major climatological events and an increase in anthropogenic impacts. As a model for exploring eco-evolutionary processes in the past and contemporary ocean we will focus primarily on Chaetoceros because this diatom genus is ancient, ubiquitous, abundant and contributes significantly to carbon export. Key findings will be additionally supported by lab-based studies using the diatom Phaeodactylum for which exemplar molecular tools exist. Specifically, the project will address: 1. What molecular features characterize genome evolution in diatoms? 2. Which processes determine diatom metapopulation structure? 3. What can ancient DNA tell us about diatom adaptations to environmental change in the past?