Cenozoic aridization in Central Eurasia shaped diversification of toad-headed agamas ( Phrynocephalus ; Agamidae, Reptilia)

• Published in: PeerJ (San Francisco, CA) CA), 2018-03, Vol.6, p.e4543-e4543, Article e4543
• Main Authors: Solovyeva, Evgeniya N, Lebedev, Vladimir S, Dunayev, Evgeniy A, Nazarov, Roman A, Bannikova, Anna A, Che, Jing, Murphy, Robert W, Poyarkov, Nikolay A
• Format: Article
• Language: English
• Subjects: Agamidae; Analysis; Asian deserts; Bayesian analysis; Biodiversity; Biogeography; Biology; Body size; Brain-derived neurotrophic factor; Climate cycles; Cytochrome; Dehydrogenases; Deoxyribonucleic acid; Deserts; Discordance; Dispersal–extinction–cladogenesis; DNA; Environmental changes; Evolution; Evolutionary genetics; Evolutionary Studies; Genealogy; Genera; Genetic testing; Habitats; History; Hybridization; Hypotheses; Identification and classification; Mitochondrial DNA; Morphology; Museums; Oscillations; Paleogeography; Phrynocephalus; Phylogenetics; Phylogeny; RAG1 protein; Reptilia; Sauria; Science; Species; Squamata; Taxonomy; Toad headed agama; Toads; Zoology
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.4543

We hypothesize the phylogenetic relationships of the agamid genus to assess how past environmental changes shaped the evolutionary and biogeographic history of these lizards and especially the impact of paleogeography and climatic factors. is one of the most diverse and taxonomically confusing lizard genera. As a key element of Palearctic deserts, it serves as a promising model for studies of historical biogeography and formation of arid habitats in Eurasia. We used 51 samples representing 33 of 40 recognized species of covering all major areas of the genus. Molecular data included four mtDNA ( , , , ; 2,703 bp) and four nuDNA protein-coding genes ( , , , ; 4,188 bp). AU-tests were implemented to test for significant differences between mtDNA- and nuDNA-based topologies. A time-calibrated phylogeny was estimated using a Bayesian relaxed molecular clock with nine fossil calibrations. We reconstructed the ancestral area of origin, biogeographic scenarios, body size, and the evolution of habitat preference. Phylogenetic analyses of nuDNA genes recovered a well-resolved and supported topology. Analyses detected significant discordance with the less-supported mtDNA genealogy. The position of conflicted greatly between the two datasets. MtDNA introgression due to ancient hybridization best explained this result. Monophyletic contained three main clades: (I) oviparous species from south-western and Middle Asia; (II) viviparous species of Qinghai-Tibetan Plateau (QTP); and (III) oviparous species of the Caspian Basin, Middle and Central Asia. originated in late Oligocene (26.9 Ma) and modern species diversified during the middle Miocene (14.8-13.5 Ma). The reconstruction of ancestral areas indicated that originated in Middle East-southern Middle Asia. Body size miniaturization likely occurred early in the history of . The common ancestor of probably preferred sandy substrates with the inclusion of clay or gravel. The time of Agaminae radiation and origin of in the late Oligocene significantly precedes the landbridge between Afro-Arabia and Eurasia in the Early Miocene. Diversification of coincides well with the mid-Miocene climatic transition when a rapid cooling of climate drove progressing aridification and the Paratethys salinity crisis. These factors likely triggered the spreading of desert habitats in Central Eurasia, which occupied. The origin of the viviparous Tibetan clade has been associated traditionally with uplifting of the QTP; however, further studie