Evolution of a genetic incompatibility in the genus Xiphophorus

Mol Biol Evol. 2013 Oct;30(10):2302-10. doi: 10.1093/molbev/mst127. Epub 2013 Jul 27.


Genetic incompatibilities are commonly observed between hybridizing species. Although this type of isolating mechanism has received considerable attention, we have few examples describing how genetic incompatibilities evolve. We investigated the evolution of two loci involved in a classic example of a Bateson-Dobzhansky-Muller (BDM) incompatibility in Xiphophorus, a genus of freshwater fishes from northern Central America. Hybrids develop a lethal melanoma due to the interaction of two loci, an oncogene and its repressor. We cloned and sequenced the putative repressor locus in 25 Xiphophorus species and an outgroup species, and determined the status of the oncogene in those species from the literature. Using phylogenetic analyses, we find evidence that a repeat region in the proximal promoter of the repressor is coevolving with the oncogene. The data support a hypothesis that departs from the standard BDM model: it appears the alleles that cause the incompatibilities have coevolved simultaneously within lineages, rather than in allopatric or temporal isolation.

Keywords: Xiphophorus; coevolution; genetic incompatibility; phylogenetic analysis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Central America
  • Cyclin-Dependent Kinase Inhibitor p15 / genetics*
  • Cyclin-Dependent Kinase Inhibitor p15 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p16 / genetics*
  • Cyclin-Dependent Kinase Inhibitor p16 / metabolism
  • Cyprinodontiformes / genetics*
  • Evolution, Molecular*
  • Female
  • Fish Diseases / genetics
  • Fish Proteins / genetics*
  • Fish Proteins / metabolism
  • Genetic Speciation
  • Hybridization, Genetic
  • Male
  • Melanoma / genetics
  • Melanoma / veterinary
  • Models, Genetic
  • Oncogenes*
  • Phylogeny
  • Promoter Regions, Genetic
  • Receptor Protein-Tyrosine Kinases / genetics*
  • Receptor Protein-Tyrosine Kinases / metabolism
  • Repetitive Sequences, Nucleic Acid
  • Selection, Genetic


  • Cyclin-Dependent Kinase Inhibitor p15
  • Cyclin-Dependent Kinase Inhibitor p16
  • Fish Proteins
  • Receptor Protein-Tyrosine Kinases
  • Xmrk protein, Xiphophorus