Species tree estimation in African Agama

Africa is renowned for its biodiversity and endemicity, yet little is known about the factors shaping them
across the continent. African Agama lizards (45 species) have a pan-continental distribution, making
them an ideal model for investigating biogeography. Many species have evolved conspicuous sexually
dimorphic traits, including extravagant breeding coloration in adult males, large adult male body sizes,
and variability in social systems among colorful versus drab species. We present a comprehensive
time-calibrated species tree for Agama, and their close relatives, using a hybrid phylogenetic–phylogenomic
approach that combines traditional Sanger sequence data from five loci for 57 species (146 samples)
with anchored phylogenomic data from 215 nuclear genes for 23 species. The Sanger data are analyzed using coalescent-based species tree inference using *BEAST, and the resulting posterior distribution
of species trees is attenuated using the phylogenomic tree as a backbone constraint. The result is a
time-calibrated species tree for Agama that includes 95% of all species, multiple samples for most species,
strong support for the major clades, and strong support for most of the initial divergence events. Diversification within Agama began approximately 23 million years ago (Ma), and separate radiations in Southern, East, West, and Northern Africa have been diversifying for >10 Myr. A suite of traits (morphological,
coloration, and sociality) are tightly correlated and show a strong signal of high morphological disparity
within clades, whereby the subsequent evolution of convergent phenotypes has accompanied diversification into new biogeographic areas.