Final answer:
Continuous variation refers to the gradual change of traits across groups, where trait values range with small gradations rather than discrete categories. This concept is important in understanding population variation and evolution, as it explains how traits blend and change over time within a species.
Step-by-step explanation:
“Continuous variation” means that change is gradual across groups and that traits shade and blend into each other. This type of variation can be seen in characteristics that exhibit a range of trait values with small gradations, such as height, skin color, or the number of individuals in a population. Continuous variation contrasts with “discontinuous variation,” where individuals show a few traits with large differences between them.
Populations might exhibit gradual geographic variation across an ecological gradient, which is another way to express that within a species, there are differences that change gradually over a geographic range. This phenomenon supports the idea that offspring appear to be a “blend” of their parents' traits, especially when we consider traits subject to continuous variation.
The concept of population variation also includes the distribution of phenotypes within a population, such as canine fur colors and patterns for domestic dogs, and even the size variations of warm-blooded mammals near the poles compared to their counterparts in warmer climates. These small changes in each generation can lead to major changes over long periods of time, illustrating one of the fundamental principles of evolution.