Independent contrasts and PGLS regression estimators are equivalent

摘要: We prove that the slope parameter of ordinary least squares regression phylogenetically independent contrasts (PICs) conducted through origin is identical to method generalized (GLSs) under a Brownian motion model evolution. This equivalence has several implications: 1. Understanding structure linear for GLS provides insight into when and why phylogeny important in comparative studies. 2. The limitations PIC analysis are same as model. In particular, phylogenetic covariance applies only response variable explanatory should be regarded fixed. Calculation PICs variables treated mathematical idiosyncrasy algorithm. 3. Since estimator best unbiased (BLUE), estimated using also BLUE. 4. If different branch lengths algorithm, no longer BLUE, so this not recommended. Finally, we discuss whether or how accommodate analyses, particularly relation problem uncertainty. discussion from both frequentist Bayesian perspectives.