Editor: Vincent Devictor
Niche conservatism in non-native birds in Europe: niche unfilling rather than niche expansion
Article first published online: 19 FEB 2013
© 2013 John Wiley & Sons Ltd
Global Ecology and Biogeography
Volume 22, Issue 8, pages 962–970, August 2013
How to Cite
Strubbe, D., Broennimann, O., Chiron, F. and Matthysen, E. (2013), Niche conservatism in non-native birds in Europe: niche unfilling rather than niche expansion. Global Ecology and Biogeography, 22: 962–970. doi: 10.1111/geb.12050
- Issue published online: 3 JUL 2013
- Article first published online: 19 FEB 2013
- FWO Vlaanderen
- National Centre of Competence in Research (NCCR) Plant Survival
- Biological invasion;
- climate/environment matching;
- niche conservatism;
- niche equivalency;
- niche shift;
- niche similarity;
- species distribution modelling
Niche conservatism, or the extent to which niches are conserved across space and time, is of special concern for the study of non-native species as it underlies predictions of invasion risk. Based on the occurrence of 28 non-native birds in Europe, we assess to what extent Grinnellian realized niches are conserved during invasion, formulate hypotheses to explain the variation in observed niche changes and test how well species distribution models can predict non-native bird occurrence in Europe.
To quantify niche changes, a recent method that applies kernel smoothers to densities of species occurrence in a gridded environmental space was used. This corrects for differences in the availability of environments between study areas and allows discrimination between ‘niche expansion’ into environments new to the species and ‘niche unfilling’, whereby the species only partially fills its niche in the invaded range. Predictions of non-native bird distribution in Europe were generated using several distribution modelling techniques.
Niche overlap between native and non-native bird populations is low, but niche changes are smaller for species having a higher propagule pressure and that were introduced longer ago. Non-native birds in Europe occupy a subset of the environments they inhabit in their native ranges. Niche expansion into novel environments is rare for most species, allowing species distribution models to accurately predict invasion risk.
Because of the recent nature of most bird introductions, species occupy only part of the suitable environments available in the invaded range. This signals that apart from purely ecological factors, patterns of niche conservatism may also be contingent on population-specific historical factors. These results also suggest that many claims of niche differences may be due to a partial filling of the native niche in the invaded range and thus do not represent true niche changes.