Unraveling the rapid radiation of crested newts, Triturus cristatus superspecies, using complete mitogenomic sequences

Background - The rapid radiation of crested newts (Triturus cristatus superspecies) comprises four morphotypes: 1) the T. karelinii group, 2) T. carnifex - T. macedonicus, 3) T. cristatus and 4) T. dobrogicus. These vary in body build and the number of rib-bearing pre-sacral vertebrae (NRBV). The phylogenetic relationships of the morphotypes have not yet been settled, despite several previous attempts, employing a variety of molecular markers. We here resolve the crested newt phylogeny by using complete mitochondrial genome sequences. Results - Bayesian inference based on the mitogenomic data yields a fully bifurcating, significantly supported tree, though Maximum Likelihood inference yields low support values. The internal branches connecting the morphotypes are short relative to the terminal branches. Seen from the root of Triturus (NRBV = 13), a basal dichotomy separates the T. karelinii group (NRBV = 13) from the remaining crested newts. The next split divides the latter assortment into T. carnifex - T. macedonicus (NRBV = 14) versus T. cristatus (NRBV = 15) and T. dobrogicus (NRBV = 16 or 17). Conclusions - We argue that the Bayesian full mitochondrial DNA phylogeny is superior to previous attempts aiming to recover the crested newt species tree. Furthermore, our new phylogeny involves a maximally parsimonious interpretation of NRBV evolution. Calibrating the phylogeny allows us to evaluate potential drivers for crested newt cladogenesis. The split between the T. karelinii group and the three other morphotypes, at ca. 10.4 Ma, is associated with the separation of the Balkan and Anatolian landmasses (12-9 Ma). No currently known vicariant events can be ascribed to the other two splits, first at ca. 9.3 Ma, separating T. carnifex - T. macedonicus, and second at ca. 8.8 Ma, splitting T. cristatus and T. dobrogicus. The crested newt morphotypes differ in the duration of their annual aquatic period. We speculate on the role that this ecological differentiation could have played during speciatio

Digest: biased male–male competition drives asymmetric introgression in lizards*

NaturalisAnimal science

Extensive cytonuclear discordance in a crested newt from the Balkan Peninsula glacial refugium

Animal sciencesNaturali

Where to draw the line? A nuclear genetic perspective on proposed range boundaries of the crested newts Triturus karelinii and T. arntzeni

The group of crested newts distributed from the southern Balkans to the southern shore of the Caspian Sea, Triturus karelinii sensu lato, comprises two species, T. karelinii in the east and T. arntzeni in the west. Three hypotheses have been forwarded defining the range of T. arntzeni, namely from northern Serbia eastwards i) in to Thrace, ii) up to the Aegean-Black Sea waterway including the Bosporus, or iii) into western Anatolia. We study 130 newts from 22 populations across this area with a panel of 40 enzyme nuclear genes. A combined analysis with the computer programs Structure and NewHybrids reveals the existence of two groups with admixture at two localities. The 'western group' comprises all European populations and a population at the southern shore of the Sea of Marmara in Asiatic Turkey, whereas the 'eastern group' is found at the Sakarya river valley in northern Anatolia, Asiatic Turkey. The admixed populations are also located in northern Anatolia. An analysis with the computer program BAPS resolves six genetic clusters, of which three represent the 'western group' and the other three coincide with the 'eastern group' and the two admixed populations. These analyses indicate that the species transition from T. arntzeni to T. karelinii is not in Thrace but in northern Anatolia. The presence of 'western' T. arntzeni to the east of 'eastern' T. karelinii indicates that the species' contact zone has a convoluted shape. Moreover, the spatial distribution of diagnostic allozymes only roughly coincides with that of two deeply divergent mitochondrial DNA haplotypes. A more detailed survey on the crested newt distribution in Anatolia is required to elucidate the picture further.Animal science

Kicking Triturus arntzeni when it's down: large-scale nuclear genetic data confirm that newts from the type locality are genetically admixed

We collected nuclear DNA data (52 markers) with next-generation sequencing for nine Triturus newt specimens, including the holotype and two of the paratypes of T. arntzeni, from the type locality at Vrtovac in eastern Serbia. We compare these data to a reference set composed of the four crested newt species distributed in eastern Serbia namely T. cristatus, T. dobrogicus, T. ivanbureschi and T. macedonicus to determine to which of these species the newts from the type locality of T. arntzeni should be attributed. The majority of alleles in individuals from Vrtovac is derived from T. macedonicus, but a considerable number of T. ivanbureschi alleles is also present; alleles typical for T. cristatus and T. dobrogicus are found at low frequency. Accordingly, we interpret Vrtovac as a T. macedonicus - T. ivanbureschi hybrid population, albeit not composed of F1 hybrids but of genetically admixed individuals derived through multiple generations of backcrossing. The data support the notion that the name T. arntzeni should not be applied to a species newly distinguished in T. karelinii sensu lato (to which the name T. ivanbureschi has been given). We conclude that because of the hybrid nature of the individuals from Vrtovac, the name T. arntzeni should be placed not only in the synonymy of T. macedonicus but also in the synonymy of T. ivanbureschi. In this study we demonstrate that next-generation sequencing can provide high quality data for type material with degraded DNA and therefore can play an important role in taxonomy.Animal science

Kicking Triturus arntzeni when it's down: large-scale nuclear genetic data confirm that newts from the type locality are genetically admixed

We collected nuclear DNA data (52 markers) with next-generation sequencing for nine Triturus newt specimens, including the holotype and two of the paratypes of T. arntzeni, from the type locality at Vrtovac in eastern Serbia. We compare these data to a reference set composed of the four crested newt species distributed in eastern Serbia namely T. cristatus, T. dobrogicus, T. ivanbureschi and T. macedonicus to determine to which of these species the newts from the type locality of T. arntzeni should be attributed. The majority of alleles in individuals from Vrtovac is derived from T. macedonicus, but a considerable number of T. ivanbureschi alleles is also present; alleles typical for T. cristatus and T. dobrogicus are found at low frequency. Accordingly, we interpret Vrtovac as a T. macedonicus - T. ivanbureschi hybrid population, albeit not composed of F1 hybrids but of genetically admixed individuals derived through multiple generations of backcrossing. The data support the notion that the name T. arntzeni should not be applied to a species newly distinguished in T. karelinii sensu lato (to which the name T. ivanbureschi has been given). We conclude that because of the hybrid nature of the individuals from Vrtovac, the name T. arntzeni should be placed not only in the synonymy of T. macedonicus but also in the synonymy of T. ivanbureschi. In this study we demonstrate that next-generation sequencing can provide high quality data for type material with degraded DNA and therefore can play an important role in taxonomy.Animal science

Genetic homogeneity in a Pontocaspian crested newt species (Triturus karelinii) suggests recent isolation of its three allopatric range sections

Animal sciencesNaturali

Hybridisatierisico’s door nieuwe boomkikker-taxa in Nederland

Animal sciencesNaturali

Exotische groene kikkers in Nederland

NaturalisAnimal science

The crested newt Triturus cristatus recolonized temperate Eurasia from an extra-Mediterranean glacial refugium

We assess the role of the Carpathians as an extra-Mediterranean glacial refugium for the crested newt Triturus cristatus. We combine a multilocus phylogeography (one mitochondrial protein-coding gene, three nuclear introns, and one major histocompatibility complex gene) with species distribution modelling (projected on current and Last Glacial Maximum climate layers). All genetic markers consistently show extensive genetic variation within and genetic depletion outside the Carpathians. The species distribution model suggests that most of the current range was unsuitable at the Last Glacial Maximum, but a small suitable area remained in the Carpathians. Triturus cristatus dramatically expanded its postglacial range, colonizing much of temperate Eurasia from a glacial refugium in the Carpathians. Within the Carpathians, T.cristatus persisted in multiple geographically discrete regions, providing further support for a Carpathian refugia within refugia' scenario.(c) 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 574-587.Naturali