Bees

Bees are a haplodiploid species. Thus, males come from unfertilised eggs and are haploid while females come from fertilised eggs and are diploid. All of the bees in a colony are sisters and males are only produced in order for the queen bee to mate or to found a new colony. Additionally, the queen tends to be monogamous such that all of her daughters always share 50% of their genetic material with one another. Since the daughters are diploids, half of their genetic material comes from their mother, which on average yields 25% relatedness between sisters. This means that, on average, daughters of a monogamous queen will be 75% related to one another. This relates to indirect fitness, which is a measure of an individual’s fitness based on the number of offspring a relative gains through that individual’s help. It is hypothesized that eusociality has evolved in bees because of this increased relatedness between sisters, as it would generate an increased gain in indirect fitness as compared to sisters that are only 50% related as would be the case if the queen were not monogamous. However, due to the fact that there is a greater fitness gain if daughter biased colonies start producing more males than females, a benefit that outweighs any indirect fitness gain that females acquire by helping make more females, this hypothesis is insufficient to explain eusociality in bees.