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Oceans Around the World - The Sunda and Sahul Shelves

Author: Bryan_P_White

Original Publication: 09/20/2012

Edited for grammar/syntax: 07/24/2019

Article 1: Crandall 2008

Vicariance patterns as a result of Pleistocene sea-level changes in the Sunda Shelf area should be present in both invertebrates and their ectosymbionts. Highly variable results across many different studies have spurred the authors to explore a more closely linked hypothesis: That patterns of genetic variation found in marine invertebrates (in this case, two seastars) should closely match that of their ectosymbionts (a mollusk and crustacean). Most of the four species did show at least some genetic structure, but it was not concordant across species, with each species displaying a different pattern of range expansion most likely due to differences in dispersal, and adult survivability.

Article 2: Crandall 2012

Sea-level changes during the end of the Last Glacial Maximum (LGM) should correspond closely with population range expansions of marine species. Prior to sea-level rises, the Sunda shelf and neighboring shelves were well above the ocean. Beginning roughly 20,000 years ago sea-levels began to rise rapidly, covering the Sunda shelf underwater and facilitating the rapid expansion of marine species into this new habitat. The authors suggest that since the genetic signal of this sea-level rise is present in so many species, this event can be used as a means of calibrating the heterogeneous rate of mutation rates of lineages through time, that is, that younger lineages tend to have higher mutation rates. The authors proclaim strong support for the idea of time dependency of molecular clocks. This is an important understanding because correlating the time of geologic events with species/population events is a critical aspect of marine phylogeography.

Article 3: Kraus 2012

Here the authors investigate a genus of freshwater crab, Parathelphusa, for its historical biogeographic distributions in the Sunda region and the relation of those distributions to Pleistocene sea-level changes. The authors suggest that if Pleistocene-aged sea-level changes are responsible for the diversification of Parathelphusa clades throughout the Sunda region, then the rate of speciation should have greatly increased during that time. However, the authors find that most clades have Miocene or Pliocene origins, all with origins from Borneo – although some speciation events did occur during the end of the Pleistocene, although rarely and via sporadic dispersal events as there have been no recent land-bridge connections.

Literature Cited

Crandall, E. D., M. E. Jones, M. M. Munoz, B. Akinronbi, M. V. Erdmann, and P. H. Barber. 2008. Comparative phylogeography of two seastars and their ectosymbionts within the Coral Triangle. Pages 5276-5290 Mol Ecol, England. doi:

Crandall, E. D., E. J. Sbrocco, T. S. DeBoer, P. H. Barber, and K. E. Carpenter. 2012. Expansion Dating: Calibrating Molecular Clocks in Marine Species from Expansions onto the Sunda Shelf Following the Last Glacial Maximum. doi:

Klaus, S., Germany, S. J. W. Goh, D. Wowor, D. Brandis, P. Koller, C. Schubart, B. Streit, R. Meier, P. K. L. Ng and D. C. J. Yeo. 2012. Out of Borneo: Neogene diversification of Sundaic freshwater crabs (Crustacea: Brachyura: Gecarcinucidae: Parathelphusa). Journal of Biogeography. doi:

bpwhite/oceans_around_world.txt · Last modified: 2019/07/26 21:21 by bpwhite