Do latex and resin canals spur plant diversification? re-examining a classic example of escape and radiate coevolution

(1) The association between increased lineage diversification rates and the evolution of latex and resin canals is widely cited as a paradigmatic example of Ehrlich and Raven’s “escape-and-radiate” hypothesis of coevolution. However, it has been over a quarter-century since the original study, and updates to phylogenetic comparative methods, plant molecular systematics, and phenotypic data warrant a reassessment of this classic finding.
(2) We gathered data on latex and resin canals across over 300 families and 1100 genera of vascular plants and conducted a multi-scale test of the association between these traits and lineage diversification rates. At a broad scale (across clades), we used sister-clade comparisons to test whether 28 canal-bearing clades had higher net diversification rates than their canal-lacking sister clades. At a finer scale (within clades), we used ancestral state reconstructions and phylogenetic models of lineage diversification rates to examine the relationship b...