Question

3.- In a colony of facultative social wasps, the dominant female wasp is the half sister of all the other wasps. Normally wasps are able to produce 4 offspring on their own. With her sisters' help, the dominant female is able to produce 10 offspring. What, normally, is the direct fitness of the sister wasps? In nature, would these wasps help out the dominant female? Explain why and what would need to change in order to get a different outcome (with respect to helping). (4)

Answer 1

Since all wasps are able to produce 4 offspring on their own, the sister wasps will also be producing 4 offspring if they directly reproduce. This is their direct fitness.

But in nature, these sister wasps will not reproduce on theur own and will help out their half sister(the dominant female) in producing and maintaining her offspring. This directly reduces the sister's fitness as they are producing no offspring of their own by helping out the dominant female, but such altruistic behaviour increases the inclusive fitness of the wasp population. If the sister didn't help and reproduced herself, then total progeny will be 8 (4 from sister, and 4 from dominant female). But if sisters help, then the total progeny becomes 10 (none from sister, 10 from dominant female). So in effect 2 offspring are produced extra if the sisters help out the dominant. This is why nature evolved altruistic behaviour on sister wasp's part to increase the inclusive fitness of the population.