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Speciation Theories - Under Construction
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FLMNH © 2005
There are three basic categories of theories which have been proposed to explain
tropical marine biodiversity patterns seen today in the Indo-Pacific. Each are shown schematically
here on this page.The Center of Overlap theory contends that a major biogeographic boundary exists in the vicinity of the Indonesian Archipelago. The high diversity peaks in this region are the result of species from the two adjacent basins overlapping.
Center of Accumulation proponents contend that species form from isolated popualtions
on the periphery of their ranges, then subsequently disperse by predominant surface currents and
accumulate in the West Pacific where we see the high diversity today.Proponents of Center of Origin theories contend that species are predominantly formed in the areas of high diversity in localized basins which were cut off from each other either during tectonic,
oceanographic or sea level changes. Subsequent dispersal has masked these original places of origin for
many species. However, some recently formed and narrowly restricted species still show their sites
of origin. Older species have slowly expanded outward over time. None of these three general theories are exclusive. In fact, speciation mechanisms that created the diversity today are most likely a mosaic of all three. Each of these theories is testable, but only with a phylogenetic hypothesis of relationship. Phylogenies provide a relative framework of speciation events.