The concept of continuous variation was first proposed by British statistician and scientist Francis Galton in the late 1800s. He observed that many physical traits (such as height, weight, and size) varied continuously within populations, rather than being divided into discrete categories. This type of variation is now known as “normal” or “bell-shaped” distribution.
While it’s true that environmental factors can influence the expression of certain traits, these effects are typically small when compared to the overall range of variation within a population. For example, someone who is genetically predisposed to be tall may not reach their full height potential if they are malnourished during childhood, but they will still be taller than someone with a genetic predisposition for short stature.
What is continuous variation?
In genetics, continuous variation is the variation of a trait that is not influenced by the environment and shows little to no change in phenotype from one generation to the next. This type of variation is often seen in quantitative traits, which are traits that can be measured on a scale (such as height or weight). Continuous variation is often contrasted with discontinuous variation, which is variation that is strongly influenced by the environment and results in large changes in phenotype from one generation to the next.
Examples of continuous variation
There are many examples of continuous variation. Body height is determined by genetic factors, but can be influenced by nutrition and health during development. Similarly, birth weight is determined by genetic factors, but can be influenced by the mother’s health during pregnancy. Skin color is determined by genetic factors, but can also be influenced by exposure to sunlight.
How is continuous variation different from other types of variation?
There are three types of variation: directives, continuous, and discontinuous. Directives are lead by the environment such as seasonalwarning colors of animals. Continuous variation is a more consistent change that is not bound by the environment. Discontinuous variation is a less consistent change and can be bound by the environment. An example of continuous variation would be human height. Although there are environmental conditions that can affect height, like nutrition, the difference in height between individuals is small and gradual. An example of discontinuous variation would be human blood type. There are four different kinds of blood, and a person either has one type or another; there is no in-between.
What causes continuous variation?
There are a number of different things that can cause continuous variation. The most common cause is genetic variation, which is the variation in the genetic make-up of individuals in a population. This type of variation can be caused by changes in the DNA sequence, or by changes in the way that the DNA is expressed (the phenotype).
How is continuous variation useful?
While discontinuous variation can be helpful in identifying different species or types of organisms, it is continuous variation that is most useful in the many ways that humans interact with other organisms. For example, when humans select plants and animals for domestication, they usually choose those individuals that exhibit the desired traits. This process, called artificial selection, has been used to create domesticated plants and animals that are very different from their wild ancestors. The phenotype of the domestic varieties is often much more extreme than that seen in nature because artificial selection can amplify small differences.
After reviewing the data, it appears that traits exhibit continuous variation but are not strongly influenced by the environment. This suggests that heritability may play a role in determining these traits. However, more research is needed to confirm this hypothesis.