In some social haplodiploid hymenoptera, like Polistes wasps, pairs of sisters s

Question

In some social haplodiploid hymenoptera, like Polistes wasps, pairs of sisters sometimes share a burrow and start colonies together. The larger, more dominant member of the pair will become reproductive, while the more subordinate member of the pair will not produce any eggs. However, she helps her dominant sister to raise offspring. Alternatively, the subordinate could abandon her sister and set up her own colony.

Absolute fitness

Relative fitness

Dominant in pair

100 x 0.9 = 90

90/90 = 1

Dominant alone

70 x .8 = 56

80/90 = .889

Subordinate in pair

0 x .9 = 0

90/90 = 1

Subordinate alone

50 x .50 = 25

50/90 = .555

A) What is the cost of staying and helping for the subordinate?

  

            B. What is the benefit of receiving help for dominants?

                       

C. Using Hamilton’s rule of rB > C, will staying and helping by the subordinate be favored if the pair are full sisters (same father and mother)? If the pair are half-sisters (different fathers, same mother)? Remember that this is a haplodiploid system!

                        Full sisters:

                        Half-sisters:

Fecundity Survival

Absolute fitness

Relative fitness

Dominant in pair

100 .9

100 x 0.9 = 90

90/90 = 1

Dominant alone

70 .8

70 x .8 = 56

80/90 = .889

Subordinate in pair

0 .9

0 x .9 = 0

90/90 = 1

Subordinate alone

50 .5

50 x .50 = 25

50/90 = .555

Explanation / Answer

A. If the subordinate stays and helps, then its own relative fitness is 1. Alone its fitness is 0.55. Change in fitness= 0.45.

For staying and helping the subordinate has to loose its own identity almost completely.

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