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Historical biogeography of Indo-western Pacific coral reef biota: is the Indonesian region a centre of origin?

Authors


Francesco Santini Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, M5S 3G5, Canada. E-mail: fsantini@zoo.utoronto.ca

Abstract

Aim

To apply the modern theory of vicariant biogeography to the study of evolution of the coral reef fauna in the Indo-western Pacific region.

Location

Indian and western Pacific Oceans.

Methods

Use of taxa ladograms and Brooks Parsimony Analysis to reconstruct relationships between geographical areas.

Results

The analysis seems to indicate that the Indonesian region, long stated to be a `centre of origin' for most of the Indo-West Pacific marine fauna, is a very derived area in the general area cladogram; and that most of the lineages may have originated in the western Indian Ocean, Australia, or the South-western Pacific (probably from lineages that had remained isolated after the breakup of the Gondwanan supercontinent, or because of the movement of island arcs). A series of events that fragmented an originally widespread biota seems to be highly congruent with geological events that caused the break up of Gondwanaland.

Main conclusions

Contrary to several previous claims, based mostly on descriptive, rather than analytical, studies, most lineages of coral reef fauna inhabiting the Indo-western Pacific region probably originated through vicariant events associated with, and following the break up of Gondwana. A general pattern of biotic distribution that is highly congruent with geological data shows that even if long range dispersal and sympatric speciation may in some cases have taken place, they have not probably been the predominant mechanism of speciation in the clades examined.

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