Elevational Goldilocks zone underlies the exceptional diversity of a large lizard radiation (Liolaemus; Liolaemidae)

Abstract

Mountains are among the most biodiverse regions on the planet, and how these landforms shape diversification through the interaction of biological traits and geo-climatic dynamics is integral to understanding global biodiversity. In this study we investigate the dual roles of climate change and mountain uplift on the evolution of a hyper diverse radiation, Liolaemus lizards, with a spatially explicit model of diversification using a reconstruction of uplift and paleotemperature in central and southern South America. The diversification model captures a hotspot for Liolaemus around 40˚S in lineages with low dispersal ability and narrow niche breadths. Under the model, speciation rates are highest in low latitudes (<35˚S) and mid-elevations (~1000m), while extinction rates are highest at higher latitudes (>35˚S) and higher elevations (>2000m). Temperature change through the Cenozoic explained variation in speciation and extinction rates through time and across different elevational bands. Our results point to the conditions of mid-elevations being optimal for diversification (i.e., Goldilocks Zone), driven by the combination of (1) a complex topography which facilitates speciation during periods of climatic change, and (2) a relatively moderate climate which enables the persistence of ectothermic lineages and buffers species from extinction. Show more