ACROPORA AND ISOPORA: THE LONG PAST AND UNCERTAIN FUTURE

The staghorn corals (genera Acropora and Isopora of the family Acroporidae) today form arguably the dominant group of reef-building Scleractinia in the world, by virtue of their high species richness and their contribution to reef structure and ecological services. In the Atlantic, their taxonomic composition has diminished since the Miocene, Isopora becoming extinct in the Pliocene and Acropora being reduced to one small extant species group. Their past contribution to reef building in the western Atlantic has arguably rivalled that of their far more diverse relatives in the Indo-Pacific: however, their future in this role appears to hang in the balance. The focus of scientific attention on the two remaining species of Acropora in the Caribbean region and their hybrid offspring provides much food for thought about what is known about Indo-Pacific taxa and how this can be interpreted to support the future continuation of the role of these corals on indo-Pacific reefs. The time is ripe to assess the status of gaps in our knowledge of these important corals in every aspect of morphology, genetics, physiology and ecology and to place these features within the context of time and place. This paper will explore some dilemmas such as present-day cryptic species from molecular research versus long-lived morphological species and species groups, marginal species, endosymbiosis, adaptation to climate change and the variety and significance of colony and life-history features of the staghorn corals.