Colonization of North America Boosted the Diversification of Whiptail Lizards

Diversification is frequently associated with change-anything from colonizing a new area to evolving a new trait. Once a lineage changes, the organisms may be able to exploit previously unavailable ecological opportunities and release pressures from predators, parasites, and competitors, which may increase the speciation rate. Modern teiid lizards originated in South America but managed to colonize and diversify in North America. We assessed whether geographic distribution, body size, and body temperatures are associated with teiid diversification using GeoHiSSE and inverse equal-splits statistics with simulation tests. We also estimated speciation rates with MiSSE to account for the effect of unmeasured variables. Moreover, we assessed the ecological niche overlap between North American (including Caribbean) teiids and their sister clade in South America. Our results indicate that only distribution range affected diversification, but we discuss that the available data might not have been enough to assess the effect of body temperatures. We also show that North American teiids have a broader ecological niche encompassing almost all environmental conditions used by their sister clade in South America but expanding mainly toward arid areas. Our results suggest that this expansion significantly impacted teiid diversification due to the seizing of ecological opportunities or ecological release, but we do not discard possible effects of phenotypic evolution.