Illustration of the four measures of local co-evolution ( A . D
, B . D
, D . D
and E . D
) along a hypothetical evolutionary tree ( C .). A. In the case of Dc 1, the co-evolution score is high when values of all the OL s along a sub-tree are similar. B. In the case of Dc 2, the co-evolution score is high when values of all the OL s along a sub-tree are correlative (i.e. the OL s tend increase/decrease on the same branches). D. Dc 3is used for finding a large subtree and a set of orthologs with identical labeling along most of a subtree. E. Dc 4is used for finding sets of orthologs that have similar monotonic/non-monotonic decreasing/increasing evolutionary pattern along a path.