High evolutionary potential of marine zooplankton
Marine holozooplankton (the microscopic animals which spend their entire life cycle in the open water column) have been sampled during AMT cruises, with the aim of unravelling the barriers to dispersal of these species along the Atlantic Ocean transect. It is typically expected that these organisms should experience gene flow over long distances as there are few obvious barriers to dispersal. However, very little work has actually been done to understand gene flow in pelagic holoplankton on a global scale.
AMT scientists conducted a review of population genetic studies of open ocean zooplankton, where they found that marine zooplankton are well poised for evolutionary responses to global change and that genetic isolation can be achieved at the scale of gyre systems (100s to 1000s of kilometres). Population genetic structure often varies across taxa, and appears to be linked to the particular ecological requirements of the organism. Theoretical studies also suggest that plankton species may respond rapidly to selection on mildly beneficial mutations due to an exceptionally large population size. In combination, these characteristics should facilitate rapid adaptive evolution to distinct oceanographic habitats in the plankton.
During an AMT cruise population genetic structure was measured within and between ocean basins in the common mesopelagic copepod, Haloptilus longicornis. Highly significant genetic structure was observed among ocean basins with the exception of relatively weak genetic divergence between the South Atlantic and Indian Oceans. Strong genetic breaks also were observed between populations in the northern and southern subtropical gyres of both the Atlantic and Pacific Oceans. In the Atlantic, a region of low abundance for H. longicornis in equatorial waters coincided with the location of the observed genetic break, suggesting the presence of a physical or biophysical barrier that effectively limits migration among subtropical gyre systems for this species. Using oceanographic data from a basin-scale transect, we provide the first environmental portrait of an open-ocean dispersal barrier for the marine plankton. Within all four Atlantic and Pacific subtropical gyres, a general lack of genetic subdivision among sites was found, as has been observed in a few other globally-distributed plankton species.
For further information see the paper entitled ;'high evolutionary potential of marine zooplankton'.
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High evolutionary potential of marine zooplankton research paper (PDF, 360kb)
You can also watch the movie explaining the contents of the paper (presented at the European Marine Biology Symposium 2013).
Norton , E. L., Goetze, E. (2013) Equatorial dispersal barriers and limited connectivity among oceans in a planktonic copepod. Limnology and Oceanography. DOI: 10.4319/lo.2013.58.5.1581
Dr Katja Peijnenburg and Prof Erica Goetze
Dr Katja Peijnenburg (left)
Research Fellow, department of Marine Zoology, Naturalis Biodiversity Center
Researcher, University of Amsterdam
Prof Erica Goetze (centre)
Assistant Professor, Department of Oceanography, University of Hawaii
Emily Norton (right)
Graduate Research Assistant, Department of Oceanography, University of Hawaii