EVOLUTION OF PAEDOMORPHOSIS IN PLETHODONTID SALAMANDERS: ECOLOGICAL CORRELATES AND RE‐EVOLUTION OF METAMORPHOSIS

Life‐history modes can profoundly impact the biology of a species, and a classic example is the dichotomy between metamorphic (biphasic) and paedomorphic (permanently aquatic) life‐history strategies in salamanders. However, despite centuries of research on this system, several basic questions about the evolution of paedomorphosis in salamanders have not been addressed. Here, we use a nearly comprehensive, time‐calibrated phylogeny of spelerpine plethodontids to reconstruct the evolution of paedomorphosis and to test if paedomorphosis is (1) reversible; (2) associated with living in caves; (3) associated with relatively dry climatic conditions on the surface; and (4) correlated with limited range size and geographic dispersal. We find that paedomorphosis arose multiple times in spelerpines. We also find evidence for re‐evolution of metamorphosis after several million years of paedomorphosis in a lineage of Eurycea from the Edwards Plateau region of Texas. We also show for the first time using phylogenetic comparative methods that paedomorphosis is highly correlated with cave‐dwelling, arid surface environments, and small geographic range sizes, providing insights into both the causes and consequences of this major life history transition.