Paso doble: A two-step Late Pleistocene range expansion in the Tyrrhenian tree frog Hyla sarda

Abstract The Tyrrhenian tree frog, Hyla sarda, is an amphibian endemic to the islands (Western Mediterranean). Previous investigations of its Pleistocene evolutionary history suggested that it colonised northern portion current range, through a spatial diffusion process from Sardinia island, during last glaciation. However, southern and portions species’ range experienced markedly different climatic conditions Late Pleistocene, suggesting possibility unusual two-step demographic expansion. Here, we use Bayesian phylogeographic approaches locate ancestral area in characterise better component this expansion event. These analyses located for H. sarda populations along central-eastern coast within previously shown host suitable bioclimatic throughout Pleistocene. Historical reconstructions clearly showed growth fits well data, with expanding later than populations. harsher occurred glacial epoch, as compared Sardinia, likely delayed frog colonisation territories, associated growth.