ok i am getting the concept that species isn't as destinct a defintion as i thought, and chromosome number isn't the determining thing (as what's in the chromosomes is more crucial).
Biologists use the BSC (biological species concept) to define species in sexually reproducing organisms (there are others, but basically revolve around the same theme. And the typological species concept for asexuals.
The BSC defines a species as a population that is reproductively isolated from other populations in the wild. Two species may look identical, possess exactly the same number of chromosomes, even have the same number of genes. But as long as they can't reproduce, they are separate species.
It should be noted that the real world & evolution make this a difficult definition to apply in all cases. Consider a phenomenon kown as ring species. A famous example are gulls that have populations that abut each other from europe/scandinavia, across siberia, across canada to newfoundland. Each population can breed with the population next to it, yet the european & canadian populations can't (or won't). Wierd huh!
Mark
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