The dynamics of adaptive evolution in microalgae in a high-CO₂ ocean.

Area of Science:

• Marine biology
• Evolutionary biology
• Genomics

Background:

• Marine microalgae can adapt to elevated carbon dioxide (CO₂) and warming.
• The evolutionary dynamics of microalgae under simultaneous high CO₂ and warming are not well understood.

Purpose of the Study:

• To investigate the evolutionary adaptation of the marine diatom Phaeodactylum tricornutum to high CO₂ and warming.
• To analyze genomic and metabolomic changes during long-term adaptation.

Main Methods:

• Whole-genome resequencing of experimental populations over a 4-year period.
• Analysis of populations under ambient, high-CO₂, warming, and combined high-CO₂ + warming conditions.
• Metabolomic analysis to complement genomic findings.

Main Results:

• Commonly selected genes across conditions and time involved protein ubiquitination, degradation, and the tricarboxylic acid (TCA) cycle.
• Unique genes selected by 4-year adaptation are linked to respiration and metabolism, supporting prolonged adaptation.
• Metabolomic data confirmed significant alterations in pathways identified through genomic analysis.

Conclusions:

• Long-term adaptation of microalgae to high CO₂ and warming involves dynamic genetic processes.
• Genomic and metabolomic integration provides insights into microalgae's response to global change.
• Findings advance understanding of microalgae adaptation strategies in a changing ocean.