Are Toad-Headed Lizards Phrynocephalus przewalskii and P. frontalis (Family Agamidae) the Same Species? Defining Species Boundaries with Morphological and Molecular Data

Agnes Gozdzik, Jinzhong Fu


Toad-headed lizards of the Phrynocephalus przewalskii complex provide a challenging case for delimiting species boundaries. We tested the species status of P. przewalskii and P. frontalis using mitochondrial DNA (mtDNA) sequence and morphological data. A phylogenetic analysis was applied to the mtDNA data and principal component analysis (PCA) was applied to the morphological data. Furthermore, Mantel tests were used to test congruence between the patristic distance matrix derived from the phylogenetic tree and Euclidean distance matrix derived from PCA. The phylogenetic tree presented deeply diverged discreet clades that largely correspond to the two putative species. Nevertheless, PCA revealed no distinct clustering of individuals. Unique maternal inheritance might explain the discrete mtDNA variations while nuclear gene based morphological variations were continuous. Mantal tests suggested the mtDNA and morphology diverged in concordance; both had evidence of a west to east clinal variation. We conclude that P. frontalis is a synonym of P. przewalskii. Furthermore, the Mantel test is a useful method to compare mtDNA data with morphological data, but insufficient to delimit species boundaries.


species validity; Mantel test; mtDNA sequence; phylogeny; PCA; multivariate morphometrics; Phrynocephalus

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