“Are wolves and coyotes generally considered the same species or even sub-species of each other?”
I’m asking you. What, then, is the definition of species?
My basic understanding is that it is grouping of animals able to interbreed and produce fertile offspring. Sounds like this is not correct if coyote-wolves are fertile. I get that taxonomy is not an exact science, however. Per my definition, if canids are all able to interbreed and produce fertile offspring, then they are really simply sub-species of the same animal - like different breeds of dogs - so closely related so as to be virtually the same animal even though the outer morphology is different. We designete them as different species for convienience sake.
On the other hand, my education on the subject is 25+ years old and I am always eager to learn.
What, besides an inability to breed fertile offspring, defines species?
So although wolves and coyotes do occasionally interbreed - a population of coyotes and a population of wolves almost exclusively breed within their own group. Moreover they have distinct characteristics brought about by having large differences in DNA. Wolves are larger and howl, coyotes are smaller and yip.
The problem comes because people like to fit things into well defined ‘boxes’ and nature is not so obliging.
For example - I walk from a forest into a swamp. Few would argue that where I started was forest; and that were I ended up was a swamp. But there was not a clear line where one side was forest and the other side was swamp. I walked through a swampy forest and then a foresty swamp before I arrived at total swamp land.
Pan chimpanzees and Bonobo chimpanzees do not interbreed in the wild (there is a river in the way and chimps do not swim) and have distinct characteristics brought about by having different DNA. Usually they are considered “sub species” of each other because they look so similar and live so close to each other.
It is exactly what one would expect if the river (the Congo IIRC) was in flood a long time ago and changed beds so that now it ran through the middle of the chimpanzee range. Not being able to cross rivers - differences accumulated in each separate population until Bonobo chimps were noticeably smaller and more sex crazed than their ‘cousins’ across the river.
Tigers and Lions are able to produce fertile offspring - but their ranges no longer overlap in the wild - and so they are different interbreeding populations and obviously (in morphology and behavior) different species.
The total inability to produce fertile offspring is a reproductive barrier that shows that there should be no argument that the two populations are the same species - but a river can be a reproductive barrier as well (leading to an accumulation of differences).
I tend to like language analogies with evolution because there are so many points of agreement. Languages change over time and different populations separated from each other tend to accumulate differences over time.
English spoken by the English and American style English are different from each other (both being different from the English of Victorian times) - but American English is not it's own language..... yet. Americans and English CAN converse together and make each other understood - with some difficulty.
But Italian and French are both derived from Latin over many years, and a speaker of only Italian cannot usually make himself understood to a speaker of only French. Clearly they grew over time to become different languages.
I hope that cleared things up rather than confusing the issue. ;)