A Phenotypic Point of View of the Adaptive Radiation of Crested Newts (Triturus cristatus Superspecies, Caudata, Amphibia)

Figure 7

Postmetamorphic skull shape changes. The analysed sample of juveniles at the stage just after metamorphosis was obtained from a laboratory breeding experiment [53]. The sample of juveniles consisted of 10 specimens of T. dobrogicus, T. macedonicus, and T. arntzeni (T. karelinii group) and 5 specimens of T. cristatus. A general procrustes analysis [55–57] was performed for the entire sample of juvenile and adult specimens of the four analysed species. We calculated the mean shape for each stage and species and performed exploratory, principal component analysis. The positions of species- and stage-specific mean shapes in the morphospace defined by the first two principal axes are given. An arrow connecting the means for juveniles and those for adult specimens in the morphospace defined by the first two principal axes visualises the direction and the amount of shape changes during skull ontogeny.