Re: Is straight comb building a trait that can be selected for?
References no doubt exist as the subject is referred to in books. But if you want references to a properly done study on it I think you will be out of luck, I doubt one exists.
I've only worked with 3 main bee types, AMM, Carniolan, and Italian. Best I've been able to observe there is little difference from one bee to another as to how "straight" they will build their combs, it is more about the way the hive is set up, and managed.
The hive looks very different to the bee, than it looks to us. Building "crooked" combs, can be a survival skill, much as it may not suit the keeper of a moveable comb hive. I think bees will retain this as part of their arsenal and doubt it could be bred out of them. Building straight comb, regardless, would be just too far away from nature.
44 years, been commercial, outfits up to 4000 hives, now 120 hives and 200 nucs as a hobby, selling bees. T (mostly).