The role of evolutionary adaptation in coral reef management and conservation

Contrary to the common belief, evolution is not necessarily slow. Numerous studies have now demonstrated very rapid evolutionary change in natural populations, including increase of a population’s stress tolerance as a... [ view full abstract ]

Contrary to the common belief, evolution is not necessarily slow. Numerous studies have now demonstrated very rapid evolutionary change in natural populations, including increase of a population’s stress tolerance as a result of a single exposure to stress. This rapid evolution is enabled by adaptive alleles that are already present in natural populations. Such alleles can be reshuffled to generate adapted phenotypes and rapidly enriched by natural selection to maintain the population’s fitness despite environmental change.

Reef-building corals exhibit genetic adaptation to local thermal conditions while maintaining genetic connectivity across broad thermal gradients. These two features are expected to facilitate both generation of adaptive genetic variation and its redistribution among populations when conditions change.

We have developed a multigene evolutionary model encapsulating these ideas, capable of producing a map of future bleaching and extinction risks across the Indo-West Pacific. We find that coral populations should be able to maintain their fitness for at least 100 years solely by redistributing existing adaptive alleles between populations. Still, bleaching risks will increase throughout the region with the exception of a few locations, most notably the mid- and southern Great Barrier Reef (GBR). These areas of the GBR emerge as the most important refuge from global warming for coral across the whole Indo-West Pacific.

Our model can be used to examine the impacts of various management strategies under different climate change scenarios. One particularly promising management intervention is assisted gene flow, or "genetic rescue", which would promote the redistribution of adaptive alleles among populations.