Variation is incredibly important in the survival of animals and plants. If we were all exactly the same (clones) and had absolutely no variation whatsoever, then one disease would wipe us out totally. In later sections, we’ll look at things that cause and encourage variation, such as genetic mutations and natural selection.

There are two categories of variation: continuous and discontinuous. Discontinuous variation can be split into distinct categories, for example, tongue rolling – the only two categories are can and can’t. Continuous variation does not fit into specific categories and has a range of values, like height or weight.          

We represent discontinuous variation with a bar graph (the one on the top) and continuous variation with a line graph (the one on the bottom).