Global coral genomic vulnerability explains recent reef losses.

Area of Science:

• Marine Biology
• Genomics
• Climate Change Adaptation

Background:

• Reef-building corals, particularly the genus Acropora, face significant declines attributed to ocean warming.
• Understanding coral adaptation mechanisms is crucial for effective conservation strategies.

Purpose of the Study:

• To characterize the genetic diversity of Acropora corals across various oceanic regions.
• To identify genomic regions associated with heat adaptation in Acropora.
• To project the distribution of heat-adapted genotypes and assess coral reef vulnerability to climate change.

Main Methods:

• Construction of a genomic database from 595 Acropora coral samples.
• Genome-environment association analyses to detect evolutionary signals of heat adaptation.
• Predictive modeling of current and future distributions of heat-adapted genotypes.

Main Results:

• Identified parallel evolutionary signals of heat adaptation in specific genomic regions across different Acropora species, linked to heat shock and symbiosis genes.
• Reefs with lower frequencies of heat-adapted genotypes exhibit higher Acropora decline rates, indicating genomic vulnerability.
• Projected a spread of heat-adapted genotypes until 2040, but with significant population mortality and genetic diversity loss.

Conclusions:

• Genetic diversity loss in Acropora corals may impair their ability to adapt to extreme heatwaves beyond 2040.
• Genomic vulnerability and diversity loss assessments are vital for identifying and prioritizing coral reefs for conservation efforts.
• The study provides critical insights into coral resilience and adaptive potential in the face of climate change.