Figure 7

Evolution of paedomorphosis in a clade of Eurycea from the Edwards Plateau. The phylogeny shows the evolution of life history in spelerpines (biphasic vs. paedomorphic). The reconstruction is drawn from the ordered, three state analysis (Figure 2), and pruned to show only the taxa with maturation data (Figures 5 and 6). Four key nodes of interest are indicated (B to E), and a transitions from biphasic to paedomorphic likely occurred between nodes C and D. Proportional probabilities subtending each node are Bayesian continuous estimates of maturation time for males (above; Figure 5) and females (below; Figure 6). Pie diagrams (also extrapolated from Figures 5 and 6), show categorical estimates for nodes B to E. Vertical lines on the graph indicate the average (symbol) and 95% HPD intervals of continuous Bayesian estimates of male (black) and female (red) maturation age for the same nodes. These analyses do not provide evidence that larval form paedomorphosis in Edwards Plateau Eurycea (node C) evolved via progenesis, but rather indicate a case of neoteny. Major accelerations in metamorphosis and maturation likely evolved in an earlier ancestor (node B; Figures 3, 5, and 6), and early maturation age was simply maintained during the later shifts in somatic development (biphasic to paedomorphic; nodes C to D).