JPR Advance Access originally published online on December 8, 2006
Journal of Plankton Research 2007 29(1):97-106; doi:10.1093/plankt/fbl074
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Spatial heterogeneity and genetic variation in the copepod Neocalanus cristatus along two transects in the North Pacific sampled by the Continuous Plankton Recorder
1 School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK 2 Sir Alister Hardy Foundation For Ocean Science, The Laboratory, Citadel Hill, The Hoe, Plymouth PL1 2PB, UK
* Corresponding Author: richard.kirby{at}plymouth.ac.uk
Received on August 24, 2006; accepted on November 20, 2006
| Abstract |
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We present a macrogeographic study of spatial heterogeneity in an important subarctic Pacific copepod and describe the first genetic analysis of population structure using Continuous Plankton Recorder (CPR) samples. Samples of Neocalanus cristatus were collected at a constant depth of
7 m from two CPR tow-routes, (i) an eastwest
6500-km transect from Vancouver Island, Canada to Hokkaido Island, Japan, and (ii) a northsouth transect of
2250 km from Anchorage, Alaska to Tacoma, Washington. Analysis of these samples revealed three features of the biology of N. cristatus. First, N. cristatus undergoes small-scale diel vertical migration that is larger among stages CVadult (36 times more abundant at 7 m at night), than stages CICIV (only 24 times higher at night). Secondly, while there were no regions where N. cristatus did not appear, each transect sampled a few large-scale macrogeographic patches. Thirdly, an analysis of molecular variation, using a partial sequence of the N. cristatus cytochrome oxidase I gene, revealed that 7.3% (P < 0.0001) of the total genetic variation among N. cristatus sampled from macrogeographic patches by the CPR could be explained by spatial heterogeneity. We suggest that spatial heterogeneity at macrogeographic scales may be important in plankton evolution.
Communicating editor: R.P. Harris