Hi, I am here again. sorry.       Just been looking at a site ,( Doing it, when rabbits go at it) , USA, where  several domesticated bunnies have escaped.   One post says that,  quote,      "Domestic rabbits are incapable of cross breeding with wild cottontails. They are 2 separate species and their DNA is not compatable " unquote.        //////Please put me right if I am wrong but I would stick my neck out and say that this is all entirely wrong. /// I would say that domestic rabbits can breed with wild rabbits ( they have not been altered that much from wild type, and mostly in colour.)  Also I would say they are the same species and that their DNA  is compatable as both  will have the lagomorph genome   Thanks once again, looking forward to an answer/comment. eileen

Surprisingly the post is correct!

Although the domestic and cotton tails may attempt to breed, the embryos will usually die before birth due to the difference in chromosomes. Domestic (European) rabbits have 22 pairs of chromosomes, cottontails have 21

Just to add in case it isn't clear (since chromosome numbers can actually vary within some species - but maybe not in mammals?) that cottontails and domestic rabbits ARE different species.

To my knowledge (hopefully someone will correct me if I'm wrong) cottontail species (of which there are actually several) have not been domesticated so all domestic bunnies in the US are derived from the Europen rabbit.

Eileen then posted again:

Thanks David and Alistair for your replies re bunnies.//// Gosh I am really surprised that the said post is correct. ///It just goes to show how surprising  some biological facts can be. ////  I am so pleased to know this. Thanks Eileen