In the Wild
In the wild rabbits live in large colonies which have very specific social structures, (these conditions cannot be replicated in captivity as the nature of keeping in tact bucks and does together would lead to a population explosion). Fighting between genders is seldom witnessed, with each gender having their own social structure and own concerns... however a doe may deter an over amerous buck this does not usually result in a full blown fight.
The buck's hierarchy is simple, the biggest, best fighter is the boss, the top buck... he will patrol his warren and fight off younger bucks that are trying to be amerous, and mate with the does within the warren... (a large warren may occasionally support several top bucks if the warren is extensive and they rarely meet.). There are often yearling bucks ready for mating and older bucks that may have lost the fight to the top buck, but are not prepared to accept the status of an outsider, these bucks 'intermediate bucks' will also patrol the warren mating with whatever does they can find and avoiding the top buck... if he were to catch them with one of his does a fight to the death would follow. There are also outsider bucks or 'bachelor bucks' these are rabbits that for whatever reason (too old, lost too many fights or simply arent interested in the girls) are not interested in trying to gain a mating, these bucks often live in small groups on the outskirts of the warren, mutal acceptance and few fights occur in this area.
The does have a more accepting structure, they will interact and engage in social grooming with each other, as long as they stay in the order of dominance (every doe will be submissive to one doe and dominant over another) creating a line hierachy. The dominant does get the best nesting sites while the submissive does are pushed to the edge of the warren. Most doe altercations are solved without fighting, just chasing, grunting and fur pulling.
Understanding these basic structures help us in understanding how our rabbits react to each other in captivity... the main difference is that pet rabbits are often speyed/neutered this takes away the bucks urge to mate and turns them into the bachelor type looking for social companionship. This means in most pet pairs the Doe is the dominant party (watch for her forcing the buck to groom her head).
Unneutered groupings more closely resemble the wild structure, groups of does will form a strict hierachy which once establish will cause few squabbles. Mixed gender groups are obviously impracticle in captive situations but these would work the same as a wild senario. And the only time unneutered bucks can successfully be kept together is if they both naturally display the most submissive traits of the outsider or bachelor group. For help in establishing your rabbits natural position on the scale read our bonding rabbits article which talks about social position.