| Phrynocephalus | |
|---|---|
| Phrynocephalus versicolor | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Family: | Agamidae |
| Subfamily: | Agaminae |
| Genus: | Phrynocephalus Kaup, 1825 |
| Species | |
|
c. 40 sp., see text |
|
Phrynocephalus, commonly called Toadhead Agamas or Toad-headed Agama, includes more than 45 species of small and medium sized agamid lizards that inhabit open arid and semiarid environments of Asia and Eastern Europe. Systematics of this genus is very complicated. And there are a lot of controversial points of view about unclear phylogeny of this group. All representatives of this genus have been adopted so called "sit and wait" hunting strategy and they actively use visual orientation when watching for food. In general, the ecological niche and role of Phrynocephalus species in lizard communities of arid environments of Asia are poorly studied, but seem to be similar to that of Phrynosoma, Cophosaurus, Holbrookia, Uta, Sceloporus in New World, as well as Moloch in Australia.
Biogeography
The toad-headed lizards of genus Phrynocephalus are distributed from northwestern China to Turkey and are one of the major components of the central Asian desert fauna. To date, published morphological and molecular phylogenetic hypotheses of Phrynocephalus are only partially congruent, and the relationships within the genus are still far from clear. We re-analyzed published mitochondrial gene sequence data (12S, 16S, cyt b, ND4-tRNALeu) by employing partition-specific modeling in a combined DNA analysis to clarify existing gaps in the phylogeny of Chinese Phrynocephalus. Using this phylogenetic framework, we inferred the genus' historical biogeography by using weighted ancestral-area analysis and dispersal-vicariance analysis in combination with a Bayesian relaxed molecular-clock approach and paleogeographical data. The partitioned Bayesian analyses support the monophyly of Phrynocephalus and its sister-group relationship with Laudakia. An earlier finding demonstrating the monophyly of the viviparous group is corroborated. However, our hypothesis of internal relationships of the oviparous group differs from a previous hypothesis as our results do not support monophyly of the oviparous taxa. Instead, the viviparous taxa form a clade with many oviparous taxa exclusive of P. helioscopus and P. mystaceus. Our results also suggest that: (1) P. putjatia is a valid species, comprising populations from Guide, Qinghai Province and Tianzhu, Gansu Province; (2) P. hongyuanensis is not a valid species, synonymized instead with P. vlangalii; (3) P. zetangensis is not a valid species and should be included in P. theobaldi; (4) the population occurring in Kuytun, Xinjiang Uygur Autonomous Region is recognized as P. guttatus instead of P. versicolor; and (5) the Lanzhou population of P. frontalis is part of P. przewalskii. Congruent with previous hypotheses, the uplift of the Tibetan Plateau played a fundamental role in the diversification of Phrynocephalus. An evolutionary scenario combining aspects of vicariance and dispersal is necessary to explain the distribution of Phrynocephalus. Bayesian divergence-time estimation suggests that Phrynocephalus originated at the Middle-Late Miocene boundary (15.16-10.4Ma), and diversified from Late Miocene to Pleistocene from a center of origin in Central Asia, Tarim Basin, and Junggar Basin temperate desert, followed by several rapid speciation events in a relatively short time