What Is a Quantitative Trait?

Quantitative trait refers to the difference in performance between individuals can only be distinguished by quantity, the variation is a continuous trait. It has two main characteristics: the variation is continuous, and the variation is susceptible to environmental conditions. Its main characteristics are: the differences between individuals are difficult to describe and need to be measured; the variation in a population is continuous; the quantitative traits are often controlled by multiple genes; ^[1]

Quantitative traits

Quantitative trait refers to the difference in performance between individuals can only be distinguished by quantity, the variation is a continuous trait. It has two main characteristics: the variation is continuous, and the variation is susceptible to environmental conditions. Its main characteristics are: the differences between individuals are difficult to describe and need to be measured; the variation in a population is continuous; quantitative traits are often controlled by multiple genes; quantitative traits are sensitive to environmental impacts. ^[1]

Another type of traits in the biological world, such as red and white, presence and absence, etc.

The differences between individuals are continuous. For example, if two corn varieties with different ear lengths are used for crossbreeding, the ear length of the offspring (F1) plant is between two

The distinction between quantitative and qualitative traits is not absolute. Because of the different classification criteria, quantitative traits can often be regarded as qualitative traits. For example, human hyperlipoproteinemia is a quantitative trait determined by a variety of genes, and certain physiological and biochemical indicators of the disease show continuous variation in the population. However, from a clinical perspective, the population can be divided into two categories: patients and normal, so it can be regarded as a quality trait. This kind of quantitative trait that distinguishes categories according to a certain amount of variation range is called threshold trait.

The genes that determine the quantitative traits are not necessarily all the inefficient genes. For example, the individuals of the mutant giant (gt) of the fruit fly are significantly larger than the wild type; the mutant dwarf (df) of the mouse is significantly smaller than the wild type; the brachytic (br The internodes were shortened due to mutations in a single gene, and the plants were short. The high stalk and dwarf pea lines used in Mendel's experiments are also a pair of major genes. In addition, the separation of one of multiple pairs of minor genes under specific conditions can also cause a distinct phenotype in the hybrid offspring. For example, in terms of rice plant height, when the other minor genes related to the height of the two lines are the same and only one pair of genes is different, the height of the plants in the hybrid offspring can be clearly divided into non-overlapping heights. Two groups.