These little bunnies (A, B, and C) were born in the same litter to the same parents, but they have different traits for the feature of ear thickness. Bunny A has thick ears, bunny B has average ears, and bunny C has thin ears. How did these bunnies end up with ear thicknesses that are different from one another even though they have the same parents? How did the gene combinations result in the different traits?
The differences in ear thickness among these bunnies can be attributed to a phenomenon called genetic variation. Genetic variation is the result of the combination of genes from both parents during the process of reproduction.
Bunny A, B, and C inherited their genes for ear thickness from their parents. Let's assume that the parents have one dominant gene for thick ears (A) and one recessive gene for thin ears (a).
When both parents reproduce, each of them donates one copy of their ear thickness gene to their offspring. This means that Bunny A received the dominant gene for thick ears (AA), Bunny B received one copy of the dominant gene and one copy of the recessive gene (Aa), and Bunny C received two copies of the recessive gene for thin ears (aa).
The dominant gene for thick ears (A) is expressed over the recessive gene for thin ears (a). Therefore, bunny A, which has two copies of the dominant gene (AA), expresses the thick ear trait. Bunny B has one dominant gene (A) and one recessive gene (a), resulting in an average ear thickness because the dominant gene overrides the recessive one, but not completely. And finally, bunny C has two copies of the recessive gene (aa), resulting in thin ears.
This variation in ear thickness occurs due to the combination of genes inherited from both parents. The specific combination of genes determines the traits expressed by each offspring, resulting in differences within the litter like in the case of the bunnies A, B, and C.