No, sorry. Many separate species can interbreed. Dogs, wolves, coyotes, etc are considered separate species, yet can interbreed.
And again, they aren't 'markers' without an 'a priori' assumption of common descent. Sorry that you can't deal with that.
No, sorry. Many separate species can interbreed. Dogs, wolves, coyotes, etc are considered separate species, yet can interbreed.
Don't forget the wholphin.
http://www.msnbc.msn.com/id/7508288
Nope. For example endogenous retroviruses (ERVs) can be identified by the fact that they have the genes for reverse transcriptase. This does not depend on any assumptions about phylogeny.
The observed fact that ERVs are found in the same place in the genomes of different species is also independent of any phylogenetic assumptions.
It's also a fact that if species are classified by whether they contain various ERVs or not then they always form a tree structure; again, this is independent of any phylogeny.
It's the last fact, that the ERV-derived tree always matches the phylogenetic tree that was constructed using non-genetic data (anatomy, behavior, geographic distribution, etc) that makes ERVs (and other genetic markers like pseudogenes) so interesting.
To sum up: by using nothing but gene sequencing, living organisms are naturally organized into a tree structure. This tree just happens to be the same as the phylogenetic tree already constructed by techniques that don't use genetics. Common descent is the simplest and obvious explanation for these facts.
True enough. What I said was that interbreeding is a criterion used for species and genus classification.
There is no agreement among experts whether the domestic dog is Canis familiaris or C. lupus familiaris, or whether red wolves are simply hybrids of coytes and gray wolves. Variety-subspecies-species is a fairly arbitrary distinction. And don't forget the chihuahua and great Dane, which have to be considered different species because they can't mate.