Gradual Adaptation Toward a Range-Expansion Phenotype Initiated the Global Radiation of Toads

Abstract

Evolutionary Hops In order for animals to colonize new environments and disperse, specific traits may be required. Toads form a large and ecologically diverse group and have achieved extremely wide distribution in a very short time frame. To test what traits may be associated with species range in modern toads, Van Bocxlaer et al. (p. 679 ; see the news story by Pennisi ) phylogenetically reconstructed the evolutionary history of morphological and physiological traits linked to the toads' geographic ranges. Toads have evolved an optimal dispersal phenotype comprising many traits, including those affecting reproductive choices and water retention, which preceded their expansion and radiation.