Oolon Colluphid

Yup. Perhaps it would help if you could define 'species'. (Sorry, that's a sort of trick -- ie 'tricky' -- question. But if Coragyps's reply isn't satisfactory, we'll need to clarify it.)

Cheers, Oolon

demoninho

Well that sort of was the point I was trying to make anyway on another board that the distintion between species was an abitrairy one, so I needed some examples where the distinction would be difficult and mostly subjective. Unfortunately now they argue I don't know the distinction between species and race, because their high school biology textbooks say this and this :banghead:

Oolon Colluphid

As always, TalkOrigins has some useful stuff on this. See Observed Instances of Speciation, especially the first part on species concepts and isolating mechanisms.

Basically, separate species are formed by the evolution of isolating mechanisms. So it's no surprise that we find in nature a whole range of interbreedability, from 'live separately and so don't get the chance', to 'sometimes interbreed, but prefer their own lot', to interbreed, but offspring are less 'fit', to interbreed rarely and offspring are less 'fit', to almost never interbreed, but can (in some situations offspring are just fine, between other groups they're knackered), to fully separate, fully isolated species... genera... families...

Thus we get races, subspecies, quasi-species, sibling species, more distantly-related species... and the degree of interbreedability varies accordingly.

And that's why 'species' is hard to define. Between closely related ones, the boundary may well be fuzzy. Hence donkeys and horses can interbreed, lions and tigers can... as can camels and llamas... Does a 'cama' mean that camels and llamas are one species, or two?

Cheers, Oolon

Wounded King

Well there are several criteria for differentiating species, none of them necessarily better than the rest. Perhaps the most commonly used one, the biological species concept (BSC), is based on reprodctive isolation. Given this usage clearly the answer to the opening post should be no, as far as naturally occurring matings go, because no two reprodcuctively isolated populations should be able to interbreed successfully.

If we stick our experimental oar in and introduce artificial matings we can make even more of a mess of our current species categorisation than there already is.

Some distinctions between species are arbitrary but the way species are arranged taxonomically doesn't neccessarily represent their status as species using the BSC.

Demosthenes

I can tell you two examples off the top of my head. Klingon and human!

Dr.GH

What is a Species, and What is Not
http://www.aaas.org/spp/dser/evoluti...ory/mayr.shtml

Coragyps

I wasn't very clear, was I? The question has been addressed, but I didn't see any studies as to whether the ends of the rings are capable of interbreeding in either the article I linked or the Nature paper on warblers. I'm aware that they don't interbreed in nature.

Coragyps

And speaking of species interbreeding - am I hallucinating, or did someone in this forum recently post a reference to a study that showed that chimpanzee sperm cold fertilize human ova (or vice versa)? I've searched, but my terms must be wrong.

Oolon Colluphid

Yes, someone did... now where the hell is it...?

Oolon

Meatros

I might have (I'm not sure); although I didn't post a link, because I didn't have one. What I was referring to was actually a speculation about the ape "Oscar", which was featured on the discovery channel (or TLC).
The chimpanzee was radically different from all other chimps, while it was alive back in the fifties (I think). It walked upright, all the time, and had a lot of characteristics that were "unusual". If memory serves, Oscar was DNA tested and had one more chromosome then humans and one less then chimps (or vice versa).

I wish I could be more helpful.