Coupled biophysical global ocean model and molecular genetic analyses identify multiple introductions of cryptogenic species

doi:10.1073/pnas.0503811102

Coupled biophysical global ocean model and molecular genetic analyses identify multiple introductions of cryptogenic species

^†School of Biological, Earth, and Environmental Sciences, ^§Centre for Environmental Modelling and Prediction, School of Mathematics, University of New South Wales, Sydney NSW 2052, Australia

Edited by Simon A. Levin, Princeton University, Princeton, NJ, and approved July 5, 2005 (received for review May 7, 2005)

Abstract

The anthropogenic introduction of exotic species is one of the greatest modern threats to marine biodiversity. Yet exotic species introductions remain difficult to predict and are easily misunderstood because knowledge of natural dispersal patterns, species diversity, and biogeography is often insufficient to distinguish between a broadly dispersed natural population and an exotic one. Here we compare a global molecular phylogeny of a representative marine meroplanktonic taxon, the moon-jellyfish Aurelia, with natural dispersion patterns predicted by a global biophysical ocean model. Despite assumed high dispersal ability, the phylogeny reveals many cryptic species and predominantly regional structure with one notable exception: the globally distributed Aurelia sp.1, which, molecular data suggest, may occasionally traverse the Pacific unaided. This possibility is refuted by the ocean model, which shows much more limited dispersion and patterns of distribution broadly consistent with modern biogeographic zones, thus identifying multiple introductions worldwide of this cryptogenic species. This approach also supports existing evidence that (i) the occurrence in Hawaii of Aurelia sp. 4 and other native Indo-West Pacific species with similar life histories is most likely due to anthropogenic translocation, and (ii) there may be a route for rare natural colonization of northeast North America by the European marine snail Littorina littorea, whose status as endemic or exotic is unclear.

Footnotes

↵ ‡ To whom correspondence should be addressed at: Evolution and Ecology, Storer Hall, University of California, Davis, One Shields Avenue, Davis, CA 95616. E-mail: mndawson{at}ucdavis.edu.
Author contributions: M.N.D., A.S.G., and M.H.E. designed research; M.N.D. and A.S.G. performed research; M.N.D., A.S.G., and M.H.E. analyzed data; and M.N.D., A.S.G., and M.H.E. wrote the paper.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: COD, cumulative occurrence distribution; COI, mitochondrial cytochrome c oxidase subunit I; NIS, nonindigenous species; nrDNA, nuclear ribosomal DNA.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database [accession nos. AY903067–AY903213 (COI) and AY935202–AY935218 (nrDNA)].