TYPE I ERROR RATES FOR TESTING GENETIC DRIFT WITH PHENOTYPIC COVARIANCE MATRICES: A SIMULATION STUDY
Article first published online: 22 AUG 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 1, pages 185–195, January 2013
How to Cite
Prôa, M., O'Higgins, P. and Monteiro, L. R. (2013), TYPE I ERROR RATES FOR TESTING GENETIC DRIFT WITH PHENOTYPIC COVARIANCE MATRICES: A SIMULATION STUDY. Evolution, 67: 185–195. doi: 10.1111/j.1558-5646.2012.01746.x
- Issue published online: 4 JAN 2013
- Article first published online: 22 AUG 2012
- Accepted manuscript online: 28 JUL 2012 07:44AM EST
- Received November 22, 2010, Accepted July 3, 2012
- Cheverud’s conjecture;
- divergence rates;
- genetic drift test;
- multivariate evolution
Studies of evolutionary divergence using quantitative genetic methods are centered on the additive genetic variance–covariance matrix (G) of correlated traits. However, estimating G properly requires large samples and complicated experimental designs. Multivariate tests for neutral evolution commonly replace average G by the pooled phenotypic within-group variance–covariance matrix (W) for evolutionary inferences, but this approach has been criticized due to the lack of exact proportionality between genetic and phenotypic matrices. In this study, we examined the consequence, in terms of type I error rates, of replacing average G by W in a test of neutral evolution that measures the regression slope between among-population variances and within-population eigenvalues (the Ackermann and Cheverud [AC] test) using a simulation approach to generate random observations under genetic drift. Our results indicate that the type I error rates for the genetic drift test are acceptable when using W instead of average G when the matrix correlation between the ancestral G and P is higher than 0.6, the average character heritability is above 0.7, and the matrices share principal components. For less-similar G and P matrices, the type I error rates would still be acceptable if the ratio between the number of generations since divergence and the effective population size (t/Ne) is smaller than 0.01 (large populations that diverged recently). When G is not known in real data, a simulation approach to estimate expected slopes for the AC test under genetic drift is discussed.