Endemic species have highly integrated phenotypes, environmental distributions and phenotype–environment relationships

Authors

  • Marie Hermant,

    Corresponding author
    1. UMR 8198 Génétique & Evolution des Populations Végétales, Université des Sciences et Technologies de Lille 1, CNRS, Villeneuve d'Ascq Cedex, France
    • UMR 6553 Ecobio Ecosystèmes, Biodiversité, Evolution, Université de Rennes 1, CNRS, Rennes, France
    Search for more papers by this author
  • Andreas Prinzing,

    1. UMR 6553 Ecobio Ecosystèmes, Biodiversité, Evolution, Université de Rennes 1, CNRS, Rennes, France
    2. Alterra Centre for Ecosystem Studies, Wageningen University and Research Center, Wageningen, The Netherlands
    Search for more papers by this author
  • Philippe Vernon,

    1. UMR 6553 Ecobio: Ecosystèmes, Biodiversité, Evolution, Université de Rennes 1, Paimpont, France
    Search for more papers by this author
  • Peter Convey,

    1. British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
    Search for more papers by this author
  • Françoise Hennion

    1. UMR 6553 Ecobio Ecosystèmes, Biodiversité, Evolution, Université de Rennes 1, CNRS, Rennes, France
    Search for more papers by this author

Correspondence: Marie Hermant, UMR 6553 Ecobio Ecosystèmes, Biodiversité, Evolution, Université de Rennes 1, CNRS, Bâtiment 14A, Av. du Général Leclerc, 35042 Rennes, France.

E-mail: mariehermant@orange.fr

Abstract

Aim

Why are some species geographically restricted? Ecological explanations suggest that endemic species may have restricted distributions because limited phenotypic variability results in narrow niches. However, studying variability of traits independently may not fully explain the interactions within and between complex phenotypes and environments. Here, we hypothesize that endemic species are restricted to a narrow range of habitats due to strong phenotypic integration (i.e. strong correlations among traits), strong environmental integration (i.e. strong correlations among the environments occupied) and strong correlations among trait–environment combinations.

Location

The Kerguelen Islands, sub-Antarctic.

Methods

We measured flowering phenology, multiple morphological characters, and species distribution along three abiotic environmental gradients (elevation, soil moisture and soil salinity) in 14 plant species whose distributions range from strictly endemic to cosmopolitan.

Results

We found that for individual species, trait means and variances were independent of endemism, but that endemics occupied higher and less variable microhabitats. However, phenotypic integration, environmental integration along the three gradients, and the strength of trait–environment correlations all increased with the level of species endemism.

Main conclusions

Higher levels of integration within and between phenotypes and environments are associated with more restricted geographical ranges in the species studied. In endemic species phenotypic integration may explain range contraction during the taxon cycle and reduce the ability to adapt to novel microhabitats formed as a result of environmental change.

Ancillary