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… and produce viable offspring. An important distinction, because without viable offspring, genetic transmission halts.

• gnatman 3y ago
  Y'all should read the article. It goes into more depth than these two comments! For example, two species can have sex, AND produce viable offspring, but NOT produce fertile offspring. Like a donkey and horse producing a typically infertile mule. Horses and donkeys are not the same species.
  • onychomys 3y ago
    And sometimes you can have two things that everybody agrees are different species but which happily hybridize (with fertile offspring) all the time! https://www.princeton.edu/news/2020/05/07/gene-flow-between-species-influences-evolution-darwins-finches https://www.princeton.edu/news/2020/05/07/gene-flow-between-...
  • eviks 3y ago
    Viable=fertile here
    • InitialLastName 3y ago
      Some mules are fertile: http://news.bbc.co.uk/2/hi/science/nature/2290491.stm http://news.bbc.co.uk/2/hi/science/nature/2290491.stm
      • eviks 3y ago
        Extremely rare exceptions like are not a challenge to classification