Species Caveats

A species is a population, or group of populations, whose members have the potential to interbreed to produce fertile, viable offspring

  • Members of a species are unable to produce fertile, viable offspring with members of a different species
  • Hybrids are infertile offspring produced from cross-breeding between two different species (e.g. mules, ligers, etc.)

There are a number of caveats to the traditional definition of a species, including:

  • Certain organisms do not reproduce sexually (e.g. bacteria) but can transfer genetic material via plasmid exchange
  • Some past organisms are known only through fossils, with no living representatives, so breeding capacity is unestablished
  • Geographically isolated populations may never come into physical contact, meaning breeding capacity is unestablished
  • It may be physically impossible for certain members of the same species to interbreed (e.g. certain dog breeds)
  • Some species spread around an area to form interlinked populations, whereby the population ‘ends’ cannot interbreed (ring species)

Ring Species

ring species