Question

Based on the fundamental principle embodied in Hamilton’s equation (rB – C > 0), the primary reason that eusociality evolves so often in hymenopteran insects (bees, wasps, and ants) is that…

Group of answer choices

a.) haplo-diploid sex determination reduces r between males and females.

b.)haplo-diploid sex determination increases relatedness between sisters.

c.) they have stingers.

d.) worker castes are always male.

e.) haplo-diploid sex determination reduces r between sisters.

Answer 1

Hamilton's celebrated explanation on the evolution of eusociality in Hymenoptera is that haplodiploid sex determination in Hymenoptera makes sisters share three quarters of their genes, whereas a daughter only receives half her genome from her mother. Hymenopteran females may therefore propagate their genes better by helping to raise reproductive sisters than by raising daughters of their own. Haplodiploidy therefore should make the evolution of nonreproductive female workers particularly likely among the Hymenoptera.

[Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. The haplodiploid sex-determination is peculiar in many ways. For example, a male has no father and cannot have sons, but he has a grandfather and can have grandsons. And if a eusocial-insect colony has only one queen, and she has only mated once, then the relatedness between workers (diploid females) in a hive or nest is ​3⁄4. This means the workers in such a monogamous single-queen colonies are significantly more closely related than in other sex determination systems where the relatedness of siblings is usually no more than ​1⁄2. It is this point which drives the kin selection theory of how eusociality evolved.

Considering the points given above, it is clear that the right answer is option b - haplo-diploid sex determination increases relatedness between sisters.