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Rare and fleeting: an example of interspecific recombination in animal mitochondrial DNA

Kate L Ciborowski1, Sofía Consuegra, Carlos García de Leániz

  • 1Institute of Zoology, Regent's Park, London NW1 4RY, UK.

Biology Letters
|July 26, 2007
PubMed

Insights

Mitochondrial DNA (mtDNA) recombination, rarely observed in animals, was detected in Atlantic salmon. This rare interspecific recombination event between Atlantic salmon and brown trout suggests a potential source of genetic variability.

Area of Science:

  • Evolutionary Biology
  • Genetics
  • Zoology

Background:

  • Animal mitochondrial DNA (mtDNA) recombination is considered a rare evolutionary event.
  • Detecting mtDNA recombination necessitates cellular heteroplasmy, arising from mutation, intramolecular recombination, or paternal mtDNA leakage.
  • Interspecific hybridization elevates the likelihood of detecting mtDNA recombinants due to increased sequence divergence and paternal leakage.

Purpose of the Study:

  • To investigate historical variation in Atlantic salmon (Salmo salar) mitochondrial DNA (mtDNA).
  • To detect and characterize instances of mtDNA recombination within salmonid populations.

Main Methods:

  • Analysis of historical variation in Atlantic salmon mtDNA.
  • Detection of recombinant haplotypes using sequence analysis.
  • Genotyping to determine nuclear genotype and assess hybridization status.

Main Results:

  • An individual Atlantic salmon exhibited a recombinant mtDNA haplotype, incorporating sequences from both Atlantic salmon and brown trout (Salmo trutta).
  • The individual was identified as a later-generation backcross, not an F1 hybrid, indicated by its nuclear genotype.
  • No other similar recombinant haplotypes were found in 717 individuals from the same and three neighboring Atlantic salmon populations sampled between 1948-2002.

Conclusions:

  • Interspecific recombination in salmonids, though rare, can occur and contribute to mtDNA variability within species.
  • The detection of such recombination has significant implications for phylogenetic studies relying on mtDNA markers.
  • Further research is warranted to understand the frequency and mechanisms of interspecific mtDNA recombination in natural populations.

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