Habitat deterioration promotes the evolution of direct development in metamorphosing species

Although metamorphosis is widespread in the animal kingdom, several species have evolved life cycle modifications to avoid complete metamorphosis. Some species, e.g., many salamanders and newts, have deleted the adult stage via a process called paedomorphosis. Others, e.g., some frog species and marine invertebrates, no longer have a distinct larval stage and reach maturation via direct development. Here we study which ecological conditions can lead to the loss of metamorphosis via the evolution of direct development. To do so, we use size-structured consumer-resource models in conjunction with the adaptive-dynamics approach. In case the larval habitat deteriorates, individuals will produce larger offspring and in concert accelerate metamorphosis. While this leads to the evolutionary transition from metamorphosis to direct development when the adult habitat is highly favourable, the population will go extinct in case the adult habitat does not provide sufficient food in order to escape ...