Genographic Project

Species = the *inability* to interbreed, or the *practice* of not interbreeding, which over millennia leads to the inability. Lions and tigers are obviously still capable of breeding, but in the wild their ranges do not overlap so it never happens. Wolves and coyotes and domestic dogs, domestic cats and Bobcats, zebras and donkeys, Bulls and yaks, bison and cows, sheep and goats, grizzly bears and polar bears, Asian elephants and African elephants, and lots of bird species all have produced offspring.

Fecundity of the resultant spawn varies.

You're conflating species and subspecies.

richard09 wrote:

The definition of species is somewhat arbitrary.

I'm not conflating, the distinction is fuzzy.

The taxonomic definitions I gave seem pretty straightforward.

What you provided does seem fuzzy, however.

Quote :

Species = the *inability* to interbreed, or the *practice* of not interbreeding, which over millennia leads to the inability

You're making it too difficult.

Taxonomically, species defines a group which has the ability to breed and produce fertile offspring. The definition doesn't remark on interbreeding or practices or evolutionary processes which remove breeding ability.

The practice of not breeding, caused by distance or other factors - by two or more groups which would otherwise be capable of breeding and producing fertile offspring - is the definition of subspecies.

If biological changes over millennia remove the ability of the disparate groups to breed, then what you have is a new species. Evolution. Look it up. It's been in all the papers.

God created everything that walketh or creepeth or swimeth, one by one. The hubris of somebody to think that that ever changes!!

Besides, I believe I have read before that even taxonomists admit that some species designations are improperly drawn, based on earlier ignorance.