Fig. 1.

Example of the evolutionary history within a particular SNP represented by a phylogeny. In the phylogenetic tree, time moves from past (left) to present (right) across the tree. The tips of the tree represent observations from the present time. Suppose the SNP represented by this tree is associated with a trait. Then, a large covariance is expected among trait values from 2 observations (e.g., the blue diamonds) sharing a large portion of their evolutionary history (shown by the branches in blue). In contrast, the 2 observations denoted by black circles share a smaller portion of their evolutionary history, so that little covariance in the corresponding trait values is expected