Population Genomics Informs Resilience and Vulnerability of Habitat-Building Coralline Algae

Area of Science:

• Marine Biology
• Genomics
• Conservation Science

Background:

• Maerl beds are crucial, biodiverse, carbon-storing habitats.
• These habitats are formed by coralline red algae but are understudied genetically.
• Two dominant species, Phymatolithon calcareum and Lithothamnion corallioides, were investigated.

Purpose of the Study:

• To provide the first draft genomes and population genomic analyses for P. calcareum and L. corallioides.
• To assess clonal diversity, population structure, and adaptation to environmental gradients.
• To inform conservation strategies for maerl habitats using genomic data.

Main Methods:

• Population genomic analyses using over 15,000 single nucleotide polymorphisms (SNPs).
• Sampling across England, Wales, and additional European sites.
• Genomic offset analyses to predict adaptation to climate change.

Main Results:

• P. calcareum showed moderate clonal diversity with some sites dominated by single genets.
• L. corallioides exhibited high clonal diversity, with most samples being distinct genets.
• Strong genetic differentiation between sites indicated limited dispersal; candidate SNPs linked to climate were identified in P. calcareum.

Conclusions:

• Contrasting clonal dynamics impact maerl population resilience.
• Genomic offset analyses suggest some populations may struggle with mid-century climate scenarios.
• Genomic insights are essential for effective conservation and restoration of maerl beds.