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aDepartamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), C/José Gutierrez Abascal, 2, 28006 Madrid, Spain;
bRui Nabeiro Biodiversity Chair, Universidade de Évora, Largo dos Colegiais, 7000 Évora, Portugal;
cLaboratoire d'Ecologie Alpine, Unité Mixte de Recherche–Centre National de la Recherche Scientifique (CNRS) 5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France; and
aDepartamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), C/José Gutierrez Abascal, 2, 28006 Madrid, Spain;
bRui Nabeiro Biodiversity Chair, Universidade de Évora, Largo dos Colegiais, 7000 Évora, Portugal;
cLaboratoire d'Ecologie Alpine, Unité Mixte de Recherche–Centre National de la Recherche Scientifique (CNRS) 5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France; and
dDepartment of Biology, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway
1
To whom correspondence may be addressed. E-mail: maraujo@mncn.csic.es
Author contributions: M.B.A., W.T., and N.G.Y. designed research; M.B.A., W.T., and N.G.Y. performed research; W.T. and N.G.Y. analyzed data; and M.B.A. wrote the paper.
Beale et al. (1) reported that species–climate associations estimated with envelope models were no better than expected by chance for 68% of the European birds studied. Beale et al. estimated species–climate associations with 4 variables, including soil water availability and ignored ≈11% of the available bird species records for Europe, i.e., all probable and confirmed records with <10 breeding pairs and all possible breeding records.
To investigate the consequences of these choices, we replicated their study using the complete set of available bird records for Europe (2). We restricted analysis to climate variables expected to impose direct constraints on bird distributions (3). Our models had higher area under the curve (AUC) values than those of Beale et al. 90% of the time (Fig. 1A). Improved model performance was mainly due to the use of more complete species distributions data (Fig. 1B). Most importantly, measured species–climate associations were better than expected by chance 72% of the time (P < 0.05), rather than 32%, as estimated by Beale et al. (1) (Fig. 2A). Estimates of significance were affected by species range size with models failing to measure associations among restricted- and wide-ranging species (Fig. 2B). Comparable results were obtained with alternative null distributions provided by Beale and Lennon (Fig. 3).
We agree with Beale et al. (1) that there are algorithmic as well as ecological uncertainties with envelope models (4–6). However, we found no evidence that species–climate associations among European birds and climate are no stronger than expected by chance. Their conclusions are, therefore, overstated.
Footnotes
The authors declare no conflict of interest.
References
1.Beale CM, Lennon JJ, Gimona A. Opening the climate envelope reveals no macroscale associations with climate in European birds. Proc Natl Acad Sci USA. 2008;105:14908–14912. doi: 10.1073/pnas.0803506105. [DOI] [PMC free article] [PubMed] [Google Scholar]
2.Hagemeijer WJM, Blair MJ. The EBCC Atlas of European Breeding Birds, Their Distribution and Abundance. London: Poyser; 1997. [Google Scholar]
4.Thuiller W, et al. Uncertainty in predictions of extinction risk. Nature. 2004 doi: 10.1038/nature02716. [DOI] [PubMed] [Google Scholar]
5.Araújo MB, Rahbek C. How does climate change affect biodiversity? Science. 2006;313:1396–1397. doi: 10.1126/science.1131758. [DOI] [PubMed] [Google Scholar]
6.Thuiller W, et al. Predicting climate change impacts on plant diversity: Where to go from here? Perspect Plant Ecol, Evol, Syst. 2008;9:137–152. [Google Scholar]
7.Fisher RA. Combining independent tests of significance. Am Stat. 1948;2:30. [Google Scholar]