Present addresses: K. Isvaran, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. B.G. Miner, Bodega Marine Laboratory, University of California-Davis, PO Box 247, 2099 Westside Rd, Bodega Bay, CA 94923, USA.
Nonlinear relationships and phylogenetically independent contrasts
Version of Record online: 9 FEB 2004
Journal of Evolutionary Biology
Volume 17, Issue 3, pages 709–715, May 2004
How to Cite
Quader, S., Isvaran, K., Hale, R. E., Miner, B. G. and Seavy, N. E. (2004), Nonlinear relationships and phylogenetically independent contrasts. Journal of Evolutionary Biology, 17: 709–715. doi: 10.1111/j.1420-9101.2004.00697.x
- Issue online: 9 FEB 2004
- Version of Record online: 9 FEB 2004
- Received 16 June 2003; revised 13 November 2003; accepted 2 December 2003
- computer simulations;
- phylogenetic comparative method;
- statistical power;
The method of phylogenetically independent contrasts is commonly used for exploring cross-taxon relationships between traits. Here we show that this phylogenetic comparative method (PCM) can fail to detect correlated evolution when the underlying relationship between traits is nonlinear. Simulations indicate that statistical power can be dramatically reduced when independent contrasts analysis is used on nonlinear relationships. We also reanalyse a published data set and demonstrate that ignoring nonlinearity can affect biological inferences. We suggest that researchers consider the shape of the relationship between traits when using independent contrasts analysis. Alternative PCMs may be more appropriate if data cannot be transformed to meet assumptions of linearity.