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Definition of a Species. General Definition. Similar physical characteristics you can observe Interbreed in the wild and have fertile offspring Distinguished genetically from other species Have common phylogeny (evolutionary derivation). Hybrid organisms.
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General Definition • Similar physical characteristics you can observe • Interbreed in the wild and have fertile offspring • Distinguished genetically from other species • Have common phylogeny (evolutionary derivation)
Hybrid organisms Most hybrids produce infertile offspring (parent species have two different numbers of chromosomes so they can’t undergo meiosis properly) Examples • Female tiger + male lion = liger • Female horse + male donkey = mule • Female horse + male zebra = zorse
Some issues to consider • What about infertile individuals? • What about in vitro fertilization? • What about two populations that could interbreed but can’t because they are geographically isolated from each other? • What about bacteria and other species that reproduce asexually?