Figure 2
From: Correlates of monoicy and dioicy in hornworts, the apparent sister group to vascular plants
Trait evolution and correlates of sexual systems in hornworts. 2A. Models of trait evolution for sexual system and spore size. (A) Traits evolve independently from each other. The evolution of each trait is described by a forward rate q01 for shifts from state 0 to state 1, and a backward rate q10 for the reverse shift. (B) Traits can evolve in a correlated fashion, such that the rate of change in one trait depends on the background state of the other. A dual transition is not allowed. Joint evolution of two traits is thus described by an eight-rate model. 2B. Maximum likelihood tree for 98 species of hornworts (from 3593 aligned nucleotides of plastid and mitochondrial DNA) with ancestral reconstruction of sexual systems (mapped as proportional likelihoods in pie diagrams above nodes). States for each terminal node are given for the following traits: sexual system (dioicous (0 ⁄ white) or monoicous (1 ⁄ black)). Large spore size (1 ⁄ black) or small spores (0 ⁄ white). Low antheridium number per chamber (1 ⁄ black) or large number (0 ⁄ white). Unknown character states are in dark grey. Numbers above branches represent bootstrap values.