Environmental drivers of metabolomic profiles within and between cryptic lineages of Montastraea cavernosa, the great star coral

INTRODUCTION: Reef restoration practitioners aim to preserve coral genetic diversity by protecting reefs and cultivating diverse genotypes in coral nurseries. However, cryptic genetic lineages in most corals complicate restoration strategies, as the role of between-lineage genetic divergence remains unclear regarding adaptation. In Montastraea cavernosa, researchers have identified cryptic lineages, some strongly segregated by depth. OBJECTIVES: We aimed to quantify lineage-specific responses to the environment that explain the genetic and ecological divergence between the two lineages. METHODS: We conducted a ten-week reciprocal transplantation experiment using two cryptic lineages restricted to shallow water (< 10 m depth), with one lineage more common on nearshore reefs and the other on offshore reefs. Following transplantation, we analyzed the corals' growth and metabolomic response to transplantation. RESULTS: Surprisingly, the strongest response was not lineage-specific. Instead, both lineages exhibited significant and similar changes in growth and metabolomic profiles, depending on the final habitat they were transplanted to. CONCLUSION: These results suggest that cryptic lineages employ similar mechanisms of adaptation and acclimatization to environmental challenges at the metabolite level, despite their genetic distinction.