Different times, similar mechanism? Convergent patterns in light-induced phenotypic plasticity in Devonian and modern corals

Modern scleractinian corals can display high phenotypic plasticity, which reflects an interplay among various environmental controls, such as sediment input, water hydrodynamics or light intensity. In particular, the latter can strongly influence the morphology of coral species living across broad depth gradients. Light intensity was also a factor shaping the colonies of extinct Palaeozoic tabulate corals (Anthozoa: Tabulata). Based on gradual transitions in morphology observed in corals from the Middle Devonian (Givetian stage, similar to 385 Ma) mesophotic coral ecosystems (MCE) of the Aferdou el Mrakib reef (Anti-Atlas mountains, Morocco) and comparative material originating from different palaeobathymetric and biogeographical settings, we show that Devonian tabulate corals, such as Roseoporella and Alveolites, were characterised by high phenotypic plasticity and the ability to dramatically change their morphology depending on the inferred light conditions. Such a mechanism is similar to that observed in modern scleractinians, e.g. Porites sillimaniana. This recurring morphological theme suggests that Palaeozoic tabulate corals shared many functional characteristics of modern scleractinians.

Automated summary

Modern scleractinian corals and extinct Palaeozoic tabulate corals both exhibit high phenotypic plasticity and can alter their morphology in response to light intensity. This study provides evidence that Devonian tabulate corals, such as Roseoporella and Alveolites, showed a similar mechanism to modern scleractinians in changing their morphology depending on light conditions. This suggests that Palaeozoic tabulate corals shared functional characteristics with modern scleractinians.