Biology – Variation | e-Consult

Continuous variation is variation that falls on a spectrum, meaning individuals can have a range of phenotypes. It is typically controlled by multiple genes, each with a small effect, as well as environmental factors. Unlike discontinuous variation, there are no distinct categories.

Human height is a classic example. It's not determined by a single gene; instead, numerous genes contribute, each influencing height to a small degree. These genes code for various proteins involved in growth and development. Environmental factors like nutrition during childhood also play a significant role.

The interaction of these multiple genes and environmental influences results in a continuous distribution of heights within a population. There isn't a clear cutoff point to define 'tall' versus 'short'; rather, there's a range of heights, often described using a bell-shaped curve (normal distribution). The variation arises from the different combinations of alleles across these multiple genes, combined with varying environmental influences.