In the Australian human population, when collecting data about the frequency of different phenotypes at the ABO blood group locus, it is possible to group all members of the population into four phenotypic classes - VCE - SSCE Biology - Question 6 - 2006 - Paper 1

This scenario presents a case of discontinuous variation. Discontinuous variation refers to traits that can be categorized distinctly, such as blood types in the ABO blood group, which can be clearly classified into A, B, AB, and O. Unlike continuous variation, which shows a range of phenotypes (like height or skin color), here the phenotypic classes are distinct and separate, fitting well into a clear classification system.