The origins of Indian Ocean Corals


jbi_v43_i2_ocOur latest publication on the origins of Indian Ocean corals had the cover page of the February 2016 issue of the Journal of Biogeography (Vol. 43) (published online on 4 November 2015).

The paper explores the historical origins of distinctly “Indian Ocean corals”, tracing their history to the ancient Tethys Sea some 20-30 million years ago, as well as new species emerging in the northern Indian Ocean and Mascarene islands and banks.

This paper completes a story that started with looking at the distribution patterns of corals across the Western Indian Ocean, and published in PLOS ONE in 2012.

The abstract of the publication is appended below, follow this link to get the publication.

 

Link to journal page

Title: An Indian Ocean centre of origin revisited: Paleogene and Neogene influences defining a biogeographic realm

The biogeography and origins of the shallow marine fauna in the western and northern Indian Ocean are poorly known. Focusing on scleractinian corals, this study synthesises evidence from extant biogeographic patterns, phylogenetics, plate tectonics and palaeoceanography to provide new support for a hypothesis on an Indian Ocean ‘centre of origin’ for shallow marine taxa.

Ten percent of Western and Northern Indian Ocean coral species are endemic, with the genera Acropora, Anomastrea, Coscinaraea, Craterastrea, Ctenella, Gyrosmilia, Horastrea, Sclerophyllia, Siderastrea and Stylophora presenting evidence for deep and shallow evolutionary origins unique to the region. Evidence for origins in the Eocene Tethys Sea and Oligocene East Africa-Arabian Province, the global hotspots of shallow tropical marine biodiversity in their time, is derived from the fossil record, clade age, presence of relict species, intra- and inter-specific genetic diversity, Atlantic affinities, and extant distributions. Evidence for Neogene origins in geologically active subregions of the Indian Ocean (Red Sea, Arabian Sea, Mascarene Islands) is derived from intra- and inter-specific genetic diversity and endemism. The passive tectonic remnant margins of Gondwana (East Africa and Madagascar coasts), combined with prevailing ocean currents, are hypothesized to have provided a stable evolutionary refuge and region of species accumulation, perhaps since the Paleogene.

The evidence supports multiple ‘centres of origin’ for Indian Ocean corals, first in the Paleogene Tethys Sea, then in the Neogene Red Sea, Arabian Sea and Mascarene Islands. The tectonically inactive East African and Madagascar coasts provide an evolutionary museum for old and new lineages, forming a second and phylogenetically distinct peak of global coral biodiversity in the Northern Mozambique Channel