MITOCHONDRIAL-DNA VARIATION IN THE CRESTED NEWT SUPERSPECIES: LIMITED CYTOPLASMIC GENE FLOW AMONG SPECIES

Area of Science:

• Evolutionary Biology
• Zoology
• Genetics

Background:

• The European crested newt complex includes four distinct species: Triturus cristatus, T. carnifex, T. dobrogicus, and T. karelini.
• These species exhibit clear morphological, chromosomal, and isozymic differences with defined transition zones.

Purpose of the Study:

• To correlate mitochondrial DNA (mtDNA) variation with species-defining morphological features.
• To quantify genetic differentiation within and among the four crested newt species.
• To identify instances of interspecific gene flow or introgression.

Main Methods:

• A comprehensive survey of mtDNA variation across 12 European countries, sampling 210 individuals from 49 sites.
• Restriction site mapping of mtDNA, analyzing 20-27 sites per individual.
• Phylogenetic analyses using UPGMA and parsimony methods, with Triturus marmoratus as an outgroup.

Main Results:

• Significant genetic differentiation (3.9–7.1% divergence) was observed among the four species' mtDNAs.
• Geographic structuring revealed two distinct mtDNA lineages within T. carnifex (3.5% divergence) and T. karelini (4.7% divergence).
• T. cristatus and T. dobrogicus showed greater mtDNA homogeneity across their ranges, potentially due to past bottlenecking or high gene flow, respectively.

Conclusions:

• mtDNA variation largely supports the distinct species status and morphological classifications.
• Limited interspecific gene flow was detected, primarily near species transition zones.
• The genetic divergence levels align with current systematic understanding, highlighting significant differentiation within T. carnifex and T. karelini.