Caste in non-Eusocial animals

I think you may have been slightly mixing cause and effect.

In your example insects, every egg the queen lays has equal potential to become a worker, drone, or future queen. It all depends on how the larva is fed. Likewise, in the one eusocial mammal, the naked mole rat, pheromones in the queen's urine cause other females to become infertile. Sterile versus fertile is not an in-born trait, but rather a developmental one.

In some mammals, the dominant members do their best to suppress the sexuality of the subordinates. This can be by chasing rivals or attacking others who attempt to mate. So while not technically sterile, the subordinates are just as unable to pass on their genes. They have little choice except to live on the edge of the herd or the pack, just following along. This isn't a parallel to worker ants or mole rats, as the non-breeders don't serve the alphas. However, these subordinates have the chance the next season to move up the ladder and become breeders.

So now the question becomes: Would there be any advantage to the species if there existed a way to make subordinates permanently sterile?

My answer is no. Here is a mathematical proof by contradiction:

Assume to the contrary that $X$ is a non-eusocial species with a permanent sterile caste. As whole $X$ must gain some advantage from this. Members of the sterile caste consume food and other resources, so they must contribute in some way to the overall health of other $X$. The only possible such contribution is to share gathered resources with the breeding members or their offspring. Thus species $X$ is eusocial. We have a logical contradition. QED

posted about 8 years ago

cobaltduck‭

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