My foundation female here, and I'm talking back when all my dogs were Australian Cattle Dogs, was the alpha dog, the gaurd dog too until my first male was old enough to take over. Then she became everyone's friend, almost apologising for his gaurding behaviour. We lost him early so that female took on the roll again until my next male was mature, then she was the nice one again. LOL. There's a saying that covers that actually, it's why have a dog and bark too?
I find that the true alpha doesn't have to assert himself, the rest just respect him. In my Shelties the alpha was a female, and the two wannabe alphas were her daughter and another sweet looking little blondie that appears to have a split personality.
When I lost my beloved alpha girl the other two had a short battle, nothing serious, and it was the daughter that has became alpha. My sheltie boys are interesting. The one that is hypothyroid bears watching because he can fire up and is jealous and protective, however I notice he backs off quickly from the dog you'd consider the least threat, a gentle dog, smaller and older. I suspect the latter could be the true alpha in the pack. They're interesting to study.