The whole BOX (Best of Opposite Sex) deal arose because in many dog (and cat) breeds there are substantial differences (size, frame, head) between the sexes. If a judge likes a particular 'look' that tends to favor one sex over the other, the BOX tends to ameliorate that. Also, since the purpose of conformation organizations like AKC (or CFA) is to "improve the breed", the judges want to put up an example of both the best male and the best female.
"Reserve Best of Breed" is just a refinement on this back in the other direction, so that the second-best or runner-up is chosen regardless of sex.
Freekitty, I'll stand corrected if it's somehow different in the Dog World!
You are right. That’s a new one on me about the cats. Those siamese are wonderful having had 8 myself.
The BOX is due to thinking that only a dog(male)can win rather than a bitch(female)can win Best of Breed or Best of Anything. LOL It is still there. They can be very sexist. You can see by looking at Angus and his littermate sister, Barbie, he is much larger than she is. The mastiff breed really shows the difference. My Keeley (Shiloh Shepherd) looks just like a male and is bigger than a lot of them. Of course, there are the judges who don’t like whites in the Shepherd breed(do you know Hitler thought they were inferior and tried to have all of them destroyed). Any vet will tell when they are born the whites are usually the healthiest and most fit. Judges may like larger dogs rather than smaller dogs or the owner political angle is always there. And it doesn’t happen in just the dog world; the horse world is really bad and cattle too. But to be fair; there are some good judges out there.