Incomplete Dominance Examples

The Augustinian monk and botanist - Gregor Mendel, was the first person to figure out that cross-breeding of two species results in a hybrid offspring which shows the traits of both parents - one of which is quite prominent (dominant) and other is hidden (recessive.) In some cases though, neither of the two traits are dominant and the offspring tends to demonstrate intermediate traits with some inclination towards the trait of either parent. This situation which is marked by no single trait being dominant or recessive is known as 'incomplete dominance'. A look at some incomplete dominance examples will make things a lot easier for you to understand.

Incomplete Dominance in Genetics

As suggested by Gregor Mendel's principle of dominance, the situation wherein the phenotype of a heterozygote is completely identical to the phenotypes of the dominant homozygotes is referred to as 'complete dominance' in genetic science - the branch of biology. On the other hand, when the phenotype of the heterozygote is not complete identical, but an intermediate of the phenotypes of homozygotes it is known as 'incomplete domination'. Given below are some examples of incomplete dominance in plants, animals as well as human beings.

Incomplete Dominance Examples in Plants
The snapdragon species of flowering plants belonging to genus Antirrhinum is the best example of incomplete dominance in plant species. These plants are typically characterized by the growth of showy white, yellow or crimson flowers. Incomplete dominance in this species can be observed when a white homozygous snapdragon is crossbred with a crimson homozygous snapdragon - the end result of which is a hybrid snapdragon species with pink flowers. This can be attributed to the difference in amount of the red colored pigment produced in each of the two sub-species. While a white homozygous snapdragon doesn't produce this pigment, red homozygous snapdragon produces it in copious amount. In case of the hybrid variety, the amount of pigment produced is half of what is produced in crimson homozygous snapdragon species.

Incomplete Dominance Examples in Animals
There is no dearth of cases of incomplete dominance when it comes to hybrid animals. One of the best examples of the same would be cross-breeding between the rex rabbit species (typically characterized by their short fur) with the angora rabbit species (typically characterized by their long fur.) Though not as short as parent rex species, the hybrid species produced as a result of this cross-breeding sport short fur - which implies that the characteristic trait of the rex species is incompletely dominant on angora species. Yet another example of incomplete dominance in animals is the crossbreeding between homozygous red bull and homozygous white cow - wherein the resulting offspring sports a roan or brownish coat consisting of a mixture of red and white shades.

Incomplete Dominance Examples in Humans
Though the list of examples of incomplete dominance in human genetics may not be very lengthy, it is far more interesting and simple to understand as compared to the same for plants and animals. When we talk about dominant and recessive traits in humans, a lot of research has been done on human hair owing to which it comes handy when explaining what incomplete dominance actually is. If one of the child's parent has curly hair, while the other has straight hair, the chances of the child having wavy hair - the intermediate between curly and straight hair are the most. Similarly, your nose and height are other attributes of your body which are affected by genetic traits - including the incompletely dominant, inherited from your parents.

Those were some of the most prominent incomplete dominance examples which highlighted the prevalence of the same in plants, animals as well as human beings. Going through these examples must have given you a rough idea as to what incomplete dominance in genetics is. You should also go ahead and try to understand what is co-dominance (which is often confused with incomplete dominance) and pseudo-dominance (which seems like but isn't complete dominance).