Spatiotemporal dimensions of a reproductive life history trait in a spiny lizard radiation (Squamata: Phrynosomatidae)

The ecological and evolutionary factors underlying life history trait variation is one of the most interesting topics in biology. Although many studies have evaluated either macroevolutionary or macroecological patterns of life history traits across several taxonomic groups, only few studies have attempted to integrate both dimensions in a single analytical framework. Here, we study how parity mode evolved across multiple scales in the radiation of spiny lizards (Squamata: Phrynosomatidae). We adopted macroecological and macroevolutionary approaches to explore how climate across spatial and temporal scales drives the evolution of viviparity in this lizard radiation. We find support for a weak signature of current climates on the geographical distribution of oviparous and viviparous species. By contrast, we detected that evolutionary transitions from oviparity to viviparity reach a peak during the MidMiocene Climatic Optimum -- a period with a profound climate change event. We suggest that this abrupt climatic cooling promoted evolutionary transitions to viviparity simultaneously across three clades in the spiny lizard radiation. The decoupling in macroecological and macroevolutionary patterns found here suggests that past climate change has played a larger role than current climates in the spatial and temporal diversification of this reproductive life history trait.