What is meristic and substantive variations?

Meristic variation refers to the countable traits in organisms, such as the number of fins in fish or the number of petals in flowers, which can vary among individuals within a species. Substantive variation, on the other hand, pertains to differences in qualitative traits, such as color patterns, size, or shape, that do not have a direct countable measure. Both types of variation are important in the study of biodiversity and evolutionary Biology, as they contribute to the understanding of species adaptation and evolution.