They just exist...no co-exist. We've got both but the local herds (18 white-tail in 4 groups and 14 mulies in 4/5 groups) stay pretty far from one another. We don't have feeders, here...that corn is picked up from our scale at work where I weighed her (440lbs). I work at a cattle feedyard and the deer usually come onto our propperty to eat the cattle-feed.
We can't hunt mulies here, though...