Environmental fluctuations accelerate molecular evolution of thermal tolerance in a marine diatom

• Published in: Nature communications 2018-04, Vol.9 (1), p.1719-14, Article 1719
• Main Authors: Schaum, C.-Elisa, Buckling, A., Smirnoff, N., Studholme, D. J., Yvon-Durocher, G.
• Format: Article
• Language: English
• Subjects: 13/31; 14/34; 14/63; 45; 45/22; 45/23; 45/77; 631/158/857; 631/181/2475; 631/326; 64; 704/106/694; Adaptation; Adaptation, Physiological - genetics; Biological evolution; Chemical composition; Climate change; Diatoms - classification; Diatoms - genetics; Divergence; Evolution, Molecular; Gene expression; Gene regulation; Gene sequencing; Genome; Genomes; Global warming; Homeostasis; Homeostasis - genetics; Hot Temperature; Humanities and Social Sciences; Molecular chains; Molecular evolution; multidisciplinary; Oxidation-Reduction; Oxidative Stress; Phenotype; Phylogeny; Plankton; Population genetics; Primary production; Science; Science (multidisciplinary); Stress, Physiological; Temperature tolerance; Thermal stress; Transcription; Variation; Whole Genome Sequencing
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-03906-5

Diatoms contribute roughly 20% of global primary production, but the factors determining their ability to adapt to global warming are unknown. Here we quantify the capacity for adaptation to warming in the marine diatom Thalassiosira pseudonana . We find that evolutionary rescue under severe (32 °C) warming is slow, but adaptation to more realistic scenarios where temperature increases are moderate (26 °C) or fluctuate between benign and severe conditions is rapid and linked to phenotypic changes in metabolic traits and elemental composition. Whole-genome re-sequencing identifies genetic divergence among populations selected in the different warming regimes and between the evolved and ancestral lineages. Consistent with the phenotypic changes, the most rapidly evolving genes are associated with transcriptional regulation, cellular responses to oxidative stress and redox homeostasis. These results demonstrate that the evolution of thermal tolerance in marine diatoms can be rapid, particularly in fluctuating environments, and is underpinned by major genomic and phenotypic change. A better mechanistic understanding of how marine diatoms adapt to global warming is pertinent to project changes in global ocean primary production. Here, Schaum et al. show substantial phenotypic and genomic changes in Thalassiosira pseudonana during a 300-generation selection experiment in stable and fluctuating environments.