Standing genetic variation fuels rapid adaptation to ocean acidification

Area of Science:

• Marine Biology
• Evolutionary Biology
• Climate Change Science

Background:

• Global climate change is causing significant environmental shifts, necessitating an understanding of species' adaptive capacities.
• Ocean acidification, a reduction in seawater pH, is a major stressor impacting marine ecosystems worldwide.

Purpose of the Study:

• To quantify phenotypic and genetic changes during rapid adaptation to reduced seawater pH in Mytilus galloprovincialis.
• To investigate the role of standing genetic variation in facilitating adaptation to ocean acidification.

Main Methods:

• A genetically diverse larval population of Mytilus galloprovincialis was reared under two pH conditions (pH 8.1 and 7.4).
• Changes in shell-size distribution and genetic variation were monitored through settlement.
• Signatures of selection on shell growth were identified in each pH environment.

Main Results:

• Phenotypic data revealed shifts in shell-size distribution in response to decreased pH.
• Genetic analyses demonstrated that standing variation was crucial for adaptation to lower pH levels.
• Differential selection pressures on shell growth were observed between the two pH treatments.

Conclusions:

• Standing genetic variation enables rapid adaptation to ocean acidification in Mytilus galloprovincialis.
• Maintaining genetic diversity is vital for enhancing the adaptive capacity of marine populations facing global change.
• This research provides insights into the mechanisms of rapid evolution under environmental stress.