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
