What Is Haplodiploidy?

Haplodiploidy is a genetic system in which sex is determined by the number of chromosome sets an individual receives:

• Females (workers and queens) develop from fertilized eggs and are diploid (two sets of chromosomes).

• Males (drones) develop from unfertilized eggs and are haploid (one set of chromosomes).

How Does Haplodiploidy Affect Relatedness?

In haplodiploid species like honey bees:

• Daughters (workers or queens) get half of their genes from their mother (the queen) and half from their father (a drone).

• Drones are haploid, so all their sperm are genetically identical, passing on the same set of genes to every daughter.

This unique system means:

• Sisters share all of their father’s genes (100%) and, on average, half of their mother’s genes (50%), resulting in an average relatedness of 75% between full sisters.

• Mother-daughter relatedness is 50%, just as in most diploid organisms.

Why Is This Important?

This higher relatedness among sisters is a key evolutionary driver behind the altruistic behaviors observed in honey bee colonies. Worker bees are more genetically invested in helping their mother (the queen) produce more sisters than they would be in producing their own offspring. This is a central concept in the evolution of eusociality and kin selection in Hymenoptera.

The Correct Explanation

Among the options provided, the reason honey bees share more genes with their sisters than with their daughters is:

(3) Haploidy diploidy sex determination system

This system, known as haplodiploidy, is responsible for the unique genetic relationships that shape the social structure and cooperative behaviors of honey bee colonies.

Correct answer: (3) Haploidy diploidy sex determination system