Facultative paedomorphosis as a mechanism promoting intraspecific niche differentiation

Organisms with complex life cycles are characterized by a metamorphosis that allows for a major habitat shift and the exploitation of alternative resources. However, metamorphosis can be bypassed in some species through a process called paedomorphosis, resulting in the retention of larval traits at the adult stage and is considered important at both micro- and macroevolutionary scales. In facultatively paedomorphic populations of newts, some individuals retain gills and a fully aquatic life at the adult stage (paedomorphs), while others undergo complete metamorphosis (metamorphs), allowing for a terrestrial life-stage. Because facultative paedomorphosis affects trophic structures and feeding mechanism of newts, one hypothesis is that it may be maintained as a trophic polymorphism, with the advantage to lessen intraspecific competition during the shared aquatic life-stage. Here, we tested this hypothesis combining stomach content data with stable isotope techniques, using carbon and nitr...