Mitochondrial-DNA Variation in the Crested Newt Superspecies: Limited Cytoplasmic Gene flow Among Species

Abstract

The crested newt has a widespread European distribution and encompasses four taxa recently elevated to full species: Triturus cristatus, T. carnifex, T. dobrogicus, and T. karelini. These are distinct on morphological, chromosomal, and isozymic grounds and have fairly sharp transition zones. A widespread survey (12 countries, 49 geographic sites, 210 individuals) of mtDNA variation (20-27 restriction enzyme sites mapped per individual) was made in order to 1) correlate mtDNA variation with morphological features defining the species, 2) determine the degree of differentiation within and among species, and 3) detect any introgression among species. The mtDNAs of these species were clearly differentiated (d = 3.9-7.1%). Additionally, geographic structuring was observed within T. carnifex and T. karelini, each displaying two divergent mitochondrial genome types (d = 3.5% and 4.7%, respectively). The other two (more northerly distributed) species were genetically homogeneous over most (T. cristatus) or all (T. dobrogicus) of their ranges. In the case of T. cristatus, one may infer bottlenecking as a result of Pleistocene glaciation events. This may also apply in part to T. dobrogicus, but high population connectedness and gene flow in this lowland river species may alone be sufficient for homogenization of mtDNA. Patterns of mtDNA variation were largely concordant with morphology; some interspecific mitochondrial gene flow was observed, but only close to or in the transition zones. Analyses of mapped restriction-site data by UPGMA and parsimony methods (using the closely related T. marmoratus as an outgroup) produce very similar dendrograms. The levels of divergence found concur with the systematics of the group, but the differentiation within T. carnifex and T. karelini is notable.

Mismatch between temperature preferences and morphology in F1 hybrid newts (Triturus carnifex×T. dobrogicus)

“…Although intermediate values of both traits have been demonstrated in hybrids between various pairs of closely related newt species (Wallis and Arntzen, 1989;Arntzen and Wallis, 1994;Brede et al, 2000), present results also confirmed morphological intermediacy for T. carnifex  T. dobrogicus offspring. This suggests that F1 hybrids poorly fit morphological space of both parental species.…”

“…Both species belong to the Triturus cristatus species group, in which members meet at narrow contact zones between their parapatric geographical ranges and their interspecific crosses produce viable and morphologically intermediate offspring (Callan and Spurway, 1951;Wallis and Arntzen, 1989;Macgregor et al, 1990;Brede et al, 2000). The most pronounced morphological differences between these species are visible in forelimb length (FLL) (T. carnifex 4T.…”

Glacial Effects on Sequence Divergence of Mitochondrial COII of Polyura eudamippus (Lepidoptera: Nymphalidae) in China

“…It has been proven that loss of genetic diversity would occur in such repetitive contractions and expansions, which would be greater in the species with rapid dispersal than in those with slow dispersal (Hewitt, 1996). Correspondingly, the genetic diversity in the northern population is usually lower than that of the populations remaining in the south (Cooper et al, 1995;Gill et al, 1993;Wallis and Arntzen, 1989).…”

Description of a new species of crested newt, previously subsumed in Triturus ivanbureschi (Amphibia: Caudata: Salamandridae)

“…Triturus ivanbureschi Arntzen andWielstra 2013 (in Wielstra et al, 2013b) comprises two candidate species and we refer to the collective as T. ivanbureschi sensu lato . The two candidate species comprising T. ivanbureschi sensu lato were initially identified based on their deep genetic divergence of mtDNA, on par with recognized crested newt species (Wallis & Arntzen, 1989;Wielstra et al, 2010). There are no known morphological differences to distinguish the two (Arntzen, 2003;Ivanović et al, 2013).…”