Seed weight increases with altitude in the Swiss Alps between related species but not among populations of individual species

Pluess, Andrea R. and Schütz, Wolfgang and Stöcklin, Jürg. (2005) Seed weight increases with altitude in the Swiss Alps between related species but not among populations of individual species. Oecologia, 144 (1). pp. 55-61.

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Official URL: http://edoc.unibas.ch/dok/A5249756

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Seed weight is a crucial plant life history trait, determining establishment success and dispersal ability. Especially in stressful environments, larger seeds may be selected at the expense of seed number, because larger seeds have a better chance of giving rise to an established offspring. We tested the hypotheses that between related species-pairs and among populations of single species a similar trend for increasing seed weight with increasing altitude should be present. Firstly, we measured seed weights from 29 species-pairs, with one species occurring in lowland areas and a congeneric species from high altitudes. Seeds of the alpine species were 28+/-8% larger than seeds from lowland species (P > 0.01). Compared to the related lowland species, 55% of the alpine species had heavier seeds, 3% (one species) had lighter, and 41% had seeds of approximately equal weight. Secondly, we compared seed weights among populations of four species from different habitats and with different life histories. Seeds from between 11 and 34 populations per species were sampled along altitudinal gradients of 800-1,500 m (ca. 800 m in Scabiosa lucida, ca. 1,000 m in Saxifraga oppositifolia, ca. 1,000 m in Epilobium fleischeri, and ca. 1,500 m in Carex flacca). In all the four species, we found no indication for heavier seeds at higher altitudes. Our results indicate a selection pressure for species with heavier seeds at higher altitude, but the trend does not seem to operate across all cases. Phylogenetic constraints may limit the correlation among altitude and seed weight, operating particularly against selection for larger seed size, the closer populations and species are related to each other.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Ehemalige Einheiten Umweltwissenschaften > Pflanzenökologie (Körner)
UniBasel Contributors:Stöcklin, Jürg
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:13 Nov 2017 16:19
Deposited On:22 Mar 2012 13:45

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