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Phylogenetic signal and linear regression on species data
Article first published online: 30 JUN 2010
© 2010 The Author. Journal compilation © 2010 British Ecological Society
Methods in Ecology and Evolution
Volume 1, Issue 4, pages 319–329, December 2010
How to Cite
Revell, L. J. (2010), Phylogenetic signal and linear regression on species data. Methods in Ecology and Evolution, 1: 319–329. doi: 10.1111/j.2041-210X.2010.00044.x
- Issue published online: 12 NOV 2010
- Article first published online: 30 JUN 2010
- Received 11 March 2010; accepted 7 May 2010 Handling Editor: Robert P. Freckleton
- comparative method;
- interspecific data;
- least squares;
- type I error
1. A common procedure in the regression analysis of interspecies data is to first test the independent and dependent variables X and Y for phylogenetic signal, and then use the presence of signal in one or both traits to justify regression analysis using phylogenetic methods such as independent contrasts or phylogenetic generalized least squares.
2. This is incorrect, because phylogenetic regression assumes that the residual error in the regression model (not in the original traits) is distributed according to a multivariate normal distribution with variances and covariances proportional to the historical relations of the species in the sample.
3. Here, I examine the consequences of justifying and applying the phylogenetic regression incorrectly. I find that when used improperly the phylogenetic regression can have poor statistical performance, even under some circumstances in which the type I error rate of the method is not inflated over its nominal level.
4. I also find, however, that when tests of phylogenetic signal in phylogenetic regression are applied properly, and in particular when phylogenetic signal in the residual error is simultaneously estimated with the regression parameters, the phylogenetic regression outperforms equivalent non-phylogenetic procedures.