Fig. 4

Ancestral tolerance plots (ATP) for annual temperature range (a) and precipitation of the driest quarter (b). Taxa are indicated by the first three letters of the species name and colored by primary clade corresponding to Fig. 2a. The ATPs for annual temperature range illustrate the conserved nature of tolerances within the swordtail clades and deep divergence within the platyfishes corresponding to the biogeographic division by the Trans-Mexican Volcanic Belt (TMVB). The dotted line in panel a denotes the separation north (above) and south (below) of the TMVB. The plot for precipitation in the driest quarter demonstrates a case where ATPs exhibited considerable overlap among the major clades and where some sub-clades diverged from their closest relatives (e.g., X. monticolus and X. mixei from the rest of the southern swordtails). Note that no such separation between species on either side of the TMVB can be drawn for panel b. Plots of ATP for all twelve variables can be found in Additional file 3