ECOLOGY/EVOLUTION: Globalization via Drift

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Science  07 Sep 2007:
Vol. 317, Issue 5843, pp. 1295a
DOI: 10.1126/science.317.5843.1295a

The evolutionary consequences of plate tectonic movements on biological organisms are often hard to reconstruct. The twin processes of extinction and dispersal tend to obscure biogeographical patterns that might otherwise be interpreted straightforwardly in the context of continental drift. The ideal group of organisms for such a study would be one that is ancient (originating before the breakup of Pangaea roughly 200 million years ago), that disperses poorly or not at all, and that still survives worldwide. Boyer et al. have focused on Cyphophthalmi—a suborder of the spiderlike long-legged harvestmen that inhabit leaf litter—which originated around 400 million years ago. A phylogeny constructed from DNA sequence data shows that almost all families of these harvestmen show clear biogeographical patterns that can be traced backward to the breakup and dispersal of the major land masses and continental islands. Relationships between the families suggest that the New Caledonian fauna (Troglosironidae) is more closely related to that of the former Gondwanan tropics (Neogoveidae) than to those of Australia and New Zealand, and this shared origin explains why they both exhibit the unusual row of teeth on the second walking-leg claw. — AMS

J. Biogeogr. 34, 10.1111/j.1365-2699.2007.01755.x (2007).

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