Seascape genomics as a new tool to empower coral reef conservation strategies: an example on north‐western Pacific Acropora digitifera
Résumé
Coral reefs are suffering a major decline due to the environmental constraints imposed
by climate change. Over the last 20 years, three major coral bleaching events
occurred in concomitance with anomalous heatwaves, provoking a severe loss of coral
cover worldwide. The conservation strategies for preserving reefs, as they are implemented
now, cannot cope with global climatic shifts. Consequently, researchers
are advocating for preservation networks to be set-up to reinforce coral adaptive potential.
However, the main obstacle to this implementation is that studies on coral
adaption are usually hard to generalize at the scale of a reef system. Here, we study
the relationships between genotype frequencies and environmental characteristics of
the sea (seascape genomics), in combination with connectivity analysis, to investigate
the adaptive potential of a flagship coral species of the Ryukyu Archipelago (Japan).
By associating genotype frequencies with descriptors of historical environmental conditions,
we discovered six genomic regions hosting polymorphisms that might promote
resistance against heat stress. Remarkably, annotations of genes in these regions
were consistent with molecular roles associated with heat responses. Furthermore,
we combined information on genetic and spatial distances between reefs to predict
connectivity at a regional scale. The combination of these results portrayed the adaptive
potential of this population: we were able to identify reefs carrying potential heat
stress adapted genotypes and to understand how they disperse to neighbouring reefs.
This information was summarized by objective, quantifiable and mappable indices covering
the whole region, which can be extremely useful for future prioritization of reefs
in conservation planning. This framework is transferable to any coral species on any
reef system and therefore represents a valuable tool for empowering preservation efforts
dedicated to the protection of coral reefs in warming oceans.
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