[Coyoteman]

Have we been able to produce a genetic strain in animals that is capable of producing fertle offspring in their own "species" but not with members of their origin "species".

Mastiff vs. Chihuahua. They could not mate without assistance.

[Dead Dog]

I meant genetically compatible, not mechanically/ergonomically compatible.

Funniest thing I've seen is a Shetland pony trying to ravish a large quarter horse mare. She probably didn't look that big from across the paddock. I think we can all relate to that.