Project: Does habitat specialization drive population genetic structure of oceanic zooplankton?

Description from NSF award abstract:
This research will test whether habitat depth specialization is a primary trait driving large-scale population genetic structure in open ocean zooplankton species. Very little is known about population connectivity in marine zooplankton. Although zooplankton were long thought to be high-gene-flow systems with little genetic differentiation among populations, recent observations have challenged this view. In fact, zooplankton species may be genetically subdivided at macrogeographic, regional, or even smaller spatial scales. Recent studies also indicate that subtle, species-specific ecological factors play an important role in controlling gene flow among plankton populations. The investigator hypothesizes that depth-related habitat, including diel vertical migration (DVM) behavior, plays a critical role in controlling dispersal of plankton among ocean regions, through interactions with ocean circulation and bathymetry. This study will compare the population genetic structures of eight planktonic copepods that utilize different depth-related habitats, in order to test key predictions of genetic structure based on the interaction of organismal depth with the oceanographic environment. The objectives of the research are to:
1) Develop novel nuclear markers that can be used to resolve genetic structure and estimate gene flow among copepod populations,
2) Characterize the spatial patterns of gene flow among populations in distinct ocean regions of the Atlantic, Pacific, and Indian Oceans for eight target species using a multilocus approach, and
3) Test the central hypothesis that depth-related habitat will significantly impact the extent of genetic structure both across and within ocean basins, the magnitude and direction of gene flow among populations, and in the timing of major slitting events within species.

Drawing on genomic resources (cDNA libraries) recently developed by the PI, five (or more) polymorphic nuclear markers will be developed for each species. These new markers will be used, in combination with the mitochondrial gene cytochrome oxidase I, to characterize the population genetic structure of each species throughout its global distribution using graph theoretic and coalescent analytical techniques. Gene flow among populations and the timing of major splitting events will be estimated under a coalescent model (IMa), and empirical support for the hypothesis of depth-related trends in population structure will be assessed using graph theoretic congruence tests. Because the depth specialization and diel vertical migration behaviors of the target species are representative of distinct zooplankton species groups, the results of this study will have broad implications for understanding and predicting the genetic structure of these important grazers in pelagic ecosystems.

Publications produced with support from this award include:
Burridge, A., Goetze, E., Raes, N., Huisman, J., Peijnenburg, K. T. C. A.  (in revision)  Global biogeography and evolution of Cuvierina pteropods.   BMC Evolutionary Biology.

Andrews, K. R., Norton, E. L., Fernandez-Silva, I., Portner^†, E. Goetze, E. (in press) Multilocus evidence for globally-distributed cryptic species and distinct populations across ocean gyres in a mesopelagic copepod.  Molecular Ecology.

Halbert , K. M. K., Goetze, E., Carlon, D. B. (2013) High cryptic diversity across the global range of the migratory planktonic copepods Pleuromamma piseki and P. gracilis.  PLOS One 8(10): e77011. doi:10.1371/journal.pone.0077011

Norton , E. L., Goetze, E. (2013) Equatorial dispersal barriers and limited connectivity among oceans in a planktonic copepod.  Limnology and Oceanography 58: 1581-1596.

Peijnenburg, K. T. C. A., Goetze, E. (2013) High evolutionary potential of marine zooplankton.  Ecology & Evolution 3(8): 2765-2781.  doi: 10.1002/ece3.644   (both authors contributed equally).

Fernandez-Silva, I., Whitney, J., Wainwright, B., Andrews, K. R., Ylitalo-Ward, H., Bowen, B. W., Toonen, R. J., Goetze, E., Karl, S. A. (2013) Microsatellites for Next-Generation Ecologists: A Post-Sequencing Bioinformatics Pipeline.  PLOS One 8(2): e55990. doi:10.1371/journal.pone.0055990

Bron, J. E., Frisch, D., Goetze, E., Johnson, S. C., Lee, C. E., Wyngaard, G. A. (2011) Observing Copepods through a Genomic Lens.  Frontiers in Zoology 8: 22.

Goetze, E. (2011) Population differentiation in the open sea: Insights from the pelagic copepod Pleuromamma xiphias.  Integrative and Comparative Biology 51: 580-597.  

Master’s theses supported under this award include:

Emily L. Norton. Empirical and biophysical modeling studies of dispersal barriers for marine plankton. (2013).  University of Hawaii at Manoa.

K. M. K. Halbert. Genetic isolation in the open sea: Cryptic diversity in the Pleuromamma piseki - P. gracilis species complex. (2013).  University of Hawaii at Manoa.