Spatial heterogeneity and genetic variation in the copepod Neocalanus cristatus along two transects in the North Pacific sampled by the Continuous Plankton Recorder

• Published in: Journal of Plankton Research
• Main Authors: Kirby, Richard R., Lindley, John A., Batten, Sonia D.
• Format: Text
• Language: English
• Published: Oxford University Press 2006
• Subjects: Article; Anchorage; Canada; Pacific; Subarctic; Alaska
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/fbl074v1; https://doi.org/10.1093/plankt/fbl074

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 samples. Samples of N. cristatus were collected at a constant depth of ∼ 7m from two CPR tow-routes, i) an east-west ∼6500 km transect from Vancouver Island, Canada to Hokkaido Island, Japan and, ii) a north-south transect of ∼2250 km from Anchorage, Alaska to Tacoma, Washington. Analysis of these samples revealed three features of the biology of N. cristatus . Firstly, N. cristatus undergoes small-scale diel vertical migration that is larger among stages CV-adult (3-6 times more abundant at 7 m at night), than stages CI-CIV (only 2-4 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 (AMOVA), 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.