Journal Article

Competition/colonization syndrome mediated by early germination in non-dispersing achenes in the heteromorphic species <i>Crepis sancta</i>

Jonathan Dubois and Pierre-Olivier Cheptou

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 110, issue 6, pages 1245-1251
Published in print November 2012 | ISSN: 0305-7364
Published online September 2012 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcs203
Competition/colonization syndrome mediated by early germination in non-dispersing achenes in the heteromorphic species Crepis sancta

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  • Ecology and Conservation
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Background and Aims

The competition–colonization trade-off theory postulates that the competitive and colonizing abilities of organisms are negatively related; this trade-off has been proposed as a major force in the maintenance of diversity. In plants, the competition–colonization trade-off is often considered to result from variation in resource partitioning, thus generating heavy competitive (non-dispersing) seeds and light (dispersing) non-competitive seeds. Here, the possibility is explored that early germination provides a competitive advantage, thus mediating competitive interactions.

Methods

Using eight populations of the heterocarpic species Crepis sancta (Asteraceae), the possibility was tested that dispersing and non-dispersing achenes differ in germination timing, and the impact of early germination on individual fitness components was analysed in the context of intraspecific competition. To evaluate whether seed reserve varies among achene types, endosperm size was also measured by analysing photographs of cross-sections taken under a binocular microscope.

Key Results and Conclusions

The results show that non-dispersing achenes germinated 4 d earlier (on average) than dispersing achenes. It is also shown that early germination provides a positive advantage for the survival and final biomass of individuals, a pattern that was consistent over the eight populations and independent of achene type. Dispersing and non-dispersing achenes did not differ in terms of seed reserve (endosperm size). It is proposed that germination phenology may mediate the competition–colonization trade-off in Crepis sancta and the evolutionary significance of this phenomenon is discussed.

Keywords: Competition–colonization trade-off; germination timing; dispersal; seed heteromorphism; Crepis sancta; Asteraceae

Journal Article.  4375 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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