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Aquatic plant shows flexible avoidance by escape from tuber predation by swans

journal contribution
posted on 01.02.2012, 00:00 authored by B Hidding, Marcel KlaassenMarcel Klaassen, T de Boer, P de Vries, B Nolet
Deeper burial of bulbs and tubers has been suggested as an escape against below-ground herbivory by vertebrates, but experimental evidence is lacking. As deep propagule burial can incur high costs of emergence after dormancy, burial depth may represent a trade-off between sprouting survival and herbivore avoidance. We tested whether burial depth of subterraneous tubers is a flexible trait in fennel pondweed (Potamogeton pectinatus), facing tuber predation by Bewick's swans (Cygnus columbianus bewickii) in shallow lakes in winter. In a four-year experiment involving eight exclosures, winter herbivory by swans and all vertebrate summer herbivory were excluded in a full-factorial design; we hence controlled for aboveground vertebrate herbivory in summer, possibly influencing tuber depth. Tuber depth was measured each September before swan arrival and each March before tuber sprouting. In accordance with our hypothesis, tuber depth in September decreased after excluding Bewick's swans in comparison to control plots. The summer exclosure showed an increase in tuber biomass and the number of shallow tubers, but not a significant effect on the mean burial depth of tuber mass. Our results suggest that a clonal plant like P. pectinatus can tune the tuber burial depth to predation pressure, either by phenotypic plasticity or genotype sorting, hence exhibiting flexible avoidance by escape. We suggest that a flexible propagule burial depth can be an effective herbivore avoidance strategy, which might be more widespread among tuber forming plant species than previously thought.

History

Journal

Basic and applied ecology

Volume

13

Issue

1

Pagination

50 - 58

Publisher

Urban und Fischer Verlag

Location

Jena, Germany

ISSN

1439-1791

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2011, Gesellschaft für Ökologie