Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comment
. 2009 Apr 21;106(16):E45-6; author reply E41-3.
doi: 10.1073/pnas.0813294106. Epub 2009 Apr 15.

Reopening the climate envelope reveals macroscale associations with climate in European birds

Miguel B Araújo, Wilfried Thuiller, Nigel G Yoccoz
Comment

Reopening the climate envelope reveals macroscale associations with climate in European birds

Miguel B Araújo et al. Proc Natl Acad Sci U S A. .
No abstract available

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Performance of climate envelopes in Beale et al. (1) and in our analysis. (A) AUC values obtained with artificial neural networks (ANN) for each of the 94 bird species modeled [out of 100 species modeled by Beale et al. (1)]. In addition to including more occurrence records per species, our analysis further differs from Beale et al. (1) in that we excluded Iceland, a few grid cells in Russia, and some of the former Soviet Republics. Axis x represents the AUC values obtained by Beale et al. (1) using annual growing degree days, mean temperature of the coldest month, soil water availability, and the coefficient of variation in the mean monthly temperature. Axis y represents AUC values obtained with the same implementation of ANN, but using growing degree days, mean temperature of the coldest month, annual precipitation, and an index of humidity calculated as the ratio of mean annual actual evapotranspiration over the mean annual potential evapotranspiration. (B) Delta between ANN AUC values obtained by Beale et al. (1) and our ANN AUC models with improved data (x), against degree of completeness in the bird species data (y), whereby negative values indicate the number of records missing in Beale et al.'s analysis. The red-shaded area shows where our ANN models yielded higher AUC values over Beale et al. (1) models because of improved completeness of the species distribution data.
Fig. 2.
Fig. 2.
Performance of our climate envelopes against the null model. (A) AUC values for real species obtained with our ANN model runs (y axis in Fig. 1A) against the AUC values obtained with a null model that generates virtual species with the same prevalence and spatial structure as the real species (the published null model Beale and colleagues). AUC values for the null distributions are the top 5% scores from random trials (i.e., P < 0.05). When using ANN models with improved response and predictor variables, real models were better than expected by chance 72% of the time [instead of 32% in Beale et al. (1)]. (B) Improvement of AUC scores for ANN models using real data as compared with ANN models with null distributions (top 5% AUC scores from random trials) against range size. Models with real data tend to under-perform with restricted- and wide-ranging species.
Fig. 3.
Fig. 3.
Analyses in Fig. 2 were repeated with an analogous, unpublished, null model provided by Beale et al. With the new null distributions, models with real data were better than expected by chance 55% of the time (instead of 32% in Beale et al.). To formally examine the null hypothesis (H0) that climate does not drive bird distributions in Europe, we combined significance values for all species using Fisher's exact test (7). When P values approach 0, it leads to rejection of the null hypothesis, thus supporting the alternative hypothesis of a statistically significant relationship between species distributions and climate. Here, the combination of P values yielded an overall P < 0.0001. Under H0, the frequency distribution of P values should also be uniform between 0 and 1, a condition that is not met with these data.
See this image and copyright information in PMC

Comment on

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. - PMC - PubMed
    1. Hagemeijer WJM, Blair MJ. The EBCC Atlas of European Breeding Birds, Their Distribution and Abundance. London: Poyser; 1997.
    1. Root TL. Environmental factors associated with avian distributional boundaries. J Biogeogr. 1988;15:489–505.
    1. Thuiller W, et al. Uncertainty in predictions of extinction risk. Nature. 2004 doi: 10.1038/nature02716. - DOI - PubMed
    1. Araújo MB, Rahbek C. How does climate change affect biodiversity? Science. 2006;313:1396–1397. - PubMed

LinkOut - more resources