Data from: Fluorescent protein-mediated colour polymorphism in reef corals: multi-copy genes extend the adaptation/acclimatization potential to variable light environments

The genomic framework that enables corals to adjust to unfavourable
conditions is crucial for coral reef survival in a rapidly changing
climate. We have explored the striking intraspecific variability in the
expression of coral pigments from the green fluorescent protein (GFP)
family to elucidate the genomic basis for the plasticity of stress
responses among reef corals. We show that multi-copy genes can greatly
increase the dynamic range over which corals can modulate transcript
levels in response to the light environment. Using the red fluorescent
protein amilFP597 in the coral Acropora millepora as a model, we
demonstrate that its expression increases with light intensity, but both
the minimal and maximal gene transcript levels vary markedly among colour
morphs. The pigment concentration in the tissue of different morphs is
strongly correlated with the number of gene copies with a particular
promoter type. These findings indicate that colour polymorphism in reef
corals can be caused by the environmentally regulated expression of
multi-copy genes. High-level expression of amilFP597 is correlated with
reduced photodamage of zooxanthellae under acute light stress, supporting
a photoprotective function of this pigment. The cluster of light-regulated
pigment genes can enable corals to invest either in expensive high-level
pigmentation, offering benefits under light stress, or to rely on low
tissue pigment concentrations and use the conserved resources for other
purposes, which is preferable in less light-exposed environments. The
genomic framework described here allows corals to pursue different
strategies to succeed in habitats with highly variable light stress
levels. In summary, our results suggest that the intraspecific plasticity
of reef corals’ stress responses is larger than previously thought.