When Two Rights Make a Wrong: The Evolutionary Genetics of Plant Hybrid Incompatibilities

Lila Fishman, Andrea L. Sweigart

Research output: Contribution to journalReview articlepeer-review

71 Scopus citations


Hybrids between flowering plant species often exhibit reduced fitness, including sterility and inviability. Such hybrid incompatibilities create barriers to genetic exchange that can promote reproductive isolation between diverging populations and, ultimately, speciation. Additionally, hybrid breakdown opens a window into hidden molecular and evolutionary processes occurring within species. Here, we review recent work on the mechanisms and origins of hybrid incompatibility in flowering plants, including both diverse genic interactions and chromosomal incompatibilities. Conflict and coevolution among and within plant genomes contributes to the evolution of some well-characterized genic incompatibilities, but duplication and drift also play important roles. Inversions, while contributing to speciation by suppressing recombination, rarely cause underdominant sterility. Translocations cause severe F1 sterility by disrupting meiosis in heterozygotes, making their fixation in outcrossing sister species a paradox. Evolutionary genomic analyses of both genic and chromosomal incompatibilities, in the context of population genetic theory, can explicitly test alternative scenarios for their origins.

Original languageEnglish
Pages (from-to)707-731
Number of pages25
JournalAnnual Review of Plant Biology
StatePublished - Apr 29 2018


  • Chromosomal rearrangement
  • Cytoplasmic male sterility
  • Dobzhansky-Muller incompatibility
  • Hybrid inviability
  • Hybrid sterility
  • Speciation


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