In amphibians, morphological differentiation and disparity at the larval and post-metamorphic ontogenetic stages can diverge, owing to various contrasting environments and different selective pressures. In the monophyletic clade of nine Triturus newt species, five different morphotypes can be recognized, but information on larval morphology is limited. Here we explore divergence of larval morphology in Triturus ivanbureschi, T. macedonicus, and their F1 hybrids. These two genetically and morphologically distinct crested newt species hybridize in nature and form a relatively wide hybrid zone in the central part of the Balkan Peninsula. Using a geometric morphometric approach and multivariate statistics, we evaluated differences of tail size and shape, colouration pattern, and the presence of a tail filament at the mid-larval stage in larvae reared under controlled laboratory conditions. We chose the tail as the main propulsive organ crucial for locomotion, feeding, and escaping predators. We found that Triturus ivanbureschi and T. macedonicus larvae differ in tail shape, but not in tail size. Two groups of F1 hybrid larvae (obtained from reciprocal crossing) were similar to each other, but differed from the parental species in size and shape of the tail, colouration pattern, and the presence of a tail filament. Our results indicate that, like adults, larvae diverge morphologically and hybrid larvae do not exhibit intermediate morphology of the parental species.
Asymmetric viability of reciprocal-cross hybrids between crested and marbled newts (Triturus cristatus and T. marmoratus).
Vertebral number is highly evolvable in salamanders and newts (family Salamandridae) and variably associated with climatic parameters.
Evolutionary and paleogeographical effects on the distribution of the Triturus cristatus superspecies in the central Balkans.
Age, growth and longevity of sympatric Trituruscristatus, T. marmoratus and their hybrids (Amphibia, Urodela): a skeletochronological comparison.
Äußere Entwicklung der Extremitäten und Stadieneinteilung der Larvenperiode von Triton taeniatus Leyd. und von Triton cristatus Laur.
Wilhelm Roux’ Archiv f. Entwicklungsmechanik d. Organismen.125:
Ontogeny of skull size and shape changes within a framework of biphasic lifestyle: a case study in six Triturus species (Amphibia, Salamandridae).
Cranial shape variation and molecular phylogenetic structure of crested newts (Trituruscristatus superspecies: Caudata, Salamandridae) in the Balkans.
Biol. J. Linn. Soc.95:
Evolutionary diversification of the limb skeleton in crested newts (Trituruscristatus superspecies, Caudata, Salamandridae).
Ann. Zool. Fenn.45:
Is mitochondrial DNA divergence of near eastern crested newts (Trituruskarelinii group) reflected by differentiation of skull shape?.
The evolution of the adult body form of the crested newt (Triturus cristatus superspecies, Caudata, Salamandridae).
J. Zool. Syst. Evol. Res.49:
Tracing glacial refugia of Triturus newts based on mitochondrial DNA phylogeography and species distribution modeling.
Front. Zool.10: 13.
Parallel tagged amplicon sequencing of transcriptome-based genetic markers for Triturus newts with the ion torrent next-generation sequencing platform.
Mol. Ecol. Resour.14: