Variation of traits along environmental gradients: role of phenotypic integration and variability within clades

• Main Author: Hermant, Marie
• Other Authors: Ecosystèmes, biodiversité, évolution Rennes (ECOBIO), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université Rennes 1, Andreas Prinzing et Françoise Hennion([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2011
• Subjects: life-history traits; phenotypic integration; realized phenotypic variability; endemism; abiotic gradients; species coexistence and interaction; Angiosperms; sub-Antarctic Islands; Central Europe; traits d'histoire de vie; intégration phénotypique; variabilité phénotypique réalisée; endémisme; gradients abiotiques; coexistence et interaction des espèces; Angiospermes; clades; îles subantarctiques; Europe Centrale; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; Antarctic; Antarc*
• Online Access: https://tel.archives-ouvertes.fr/tel-00588294; https://tel.archives-ouvertes.fr/tel-00588294/document; https://tel.archives-ouvertes.fr/tel-00588294/file/These_Marie_Hermant_2011.pdf

The response of traits to the environment has been studied mainly at the level of trait means within and across species and lineages and has recently been extended to intraspecific trait variability. However, traits may respond to the constraints of a given environment also in terms of (i) increased mutual determination of traits within individuals and populations, i.e. increased phenotypic integration, and (ii) decreased variation of traits within entire phylogenetic lineages. Here we tested: (i) the effects of abiotic and biotic environments on phenotypic integration within sub-Antarctic plant species and the ecological and biogeographic consequences of a strong phenotypic integration, and (ii) the effects of abiotic and biotic environments on the phenotypic variability realized within Angiosperm genera of Central Europe. Regarding the first aspect, we found that phenotypic integration is higher under stressful abiotic conditions. The increase in phenotypic integration occurs at small spatial scales and may constrain the large scale flexibility of growth and reproductive strategies. We also found that strong phenotypic and environmental integration may contribute to endemism of some sub-Antarctic species, probably through a long-term specialization of these species to their habitat. Regarding the second aspect, we found that phenotypic variability realized within genera of Central Europe is higher under intermediate abiotic conditions, reflecting increased independence of traits from the abiotic environment. We also found that the number of coexisting species is highly conserved within genera. Intermediate levels of coexistence tend to correspond to both intermediate positions along abiotic gradients and to highest levels of variability of certain traits. This suggests a role of numerous but still predictable biotic interactions for the maintenance (or evolution) of high levels of trait variability within clades. Overall, the results of both aspects suggest the capacity of species to respond to environmental ...