Figure 1.

Nine different maximum likelihood models of continuous trait evolution employed in CoMET, after Oakley et al. (2005). The models predict that change in trait value increases monotonically with the “time” available for change. Time available for change is estimated in different ways for different models, as indicated by different variables above branches of a hypothetical phylogenetic tree. Branches labeled “Gi” assume trait change is equal to genetic (or other) distance of that branch. Those labeled “U” assume a unit (equal) amount of change, and those labeled “Fi” are estimated from the trait data itself (free). Branches labeled “0” assume no change in trait has occurred along that branch. Columns represent three different classes of models. The pure phylogenetic class assumes trait change occurs on every branch of the phylogeny, the non-phylogenetic class assumes trait change occurs only along terminal branches, and the punctuated class assumes trait change occurs on only one of every pair of descendent branches.