The Importance of Intraspecific Variation for Niche Differentiation and Species Distribution Models: The Ecologically Diverse Frog Pleurodema thaul as Study Case

Abstract

Environmental shifts are projected to lead to expansions, contractions and shifts in the geographic range of species in response to climate change. Most distribution forecasting methods assume that species respond to the environment as an undifferentiated entity along their entire distribution. However, environmental heterogeneity along a species’ range plays a key role in driving the evolutionary trajectories of populations and species by determining intraspecific variation in morphological, physiological and life history traits. Therefore, for widely distributed species with phylogeographic structure, the construction of SDM where lineages are pooled within the species level might not accurately describe the niche of sets of lineages that are adapted to different climatic conditions. Pleurodema thaul is an endemic frog distributed from the Atacama Desert to the temperate rainforest in southern Chile and Argentina. Along this latitudinal gradient, populations exhibit variation in thermal physiology, life history traits and phylogenetic structure. We evaluated whether evolutionary lineages differ in their environmental and geographic niches and determined how phylogenetic, environmental and geographical distances covary between clades. Our results indicate that: (i) all clades of this species differ in their estimated niches, (ii) there is little overlap between geographic areas and environmental niches estimated for each clade of P. thaul and (iii) phylogenetic distances among clades of P. thaul are not correlated with environmental nor geographical distances. The development of models restricted to species’ genetic lineages can become an important first step to determine how environmental changes are going to affect the distribution of species.