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Predatory cues drive colony size reduction in marine diatoms
  • Kristie Rigby,
  • Erik Selander
Kristie Rigby
University of Gothenburg
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Erik Selander
University of Gothenburg
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Abstract

1. Chain formation is common feature among non-motile marine phytoplankton. Several theories exist around the potential benefits of larger colonies. 2. Here we test the hypothesis that predation is one of the evolutionary drivers behind chain formation and chain length plasticity. We exposed cultures of Thalassiosira rotula, Chaetoceros curvisetus and Chaetoceros affinis to copepodamides, a chemical alarm signal from copepods. This was coupled with a grazing experiment which compared grazing rates on different chain lengths. 3. Our results show that T. rotula and C. curvisetus decreased their chain lengths by 79 % and 49 %, respectively, in response to copepodamides. Single cells and short chains were grazed at lower rates and the copepodamide driven size shift led to 30 % and 12 % lower grazing in T. rotula and C. curvisetus respectively. C. affinis did not respond to copepodamides and did not show the same size dependent clearance rate. 4. We found that more chain forming diatoms respond to predatory cues from copepods than previously known, and that predation is likely an important driver in the evolution of colony size and colony size plasticity.

Peer review status:UNDER REVIEW

18 Aug 2020Submitted to Ecology and Evolution
25 Aug 2020Assigned to Editor
25 Aug 2020Submission Checks Completed
25 Aug 2020Reviewer(s) Assigned
14 Sep 2020Review(s) Completed, Editorial Evaluation Pending