There is a great deal of variation within nearly every population of organisms. Variation arises from a combination of genetic and environmental causes, each contributing equally on average. Owls, squirrels, rabbits and bears differ from each other by their physical characteristics, size and temperament. So do whales, porpoises, dorado fish, and most other populations of organisms. But within the population, there is also dramatic variation.
Variation is important for the continued survival of a species in changing environments.
This lesson has two parts, Mendelian Genetics and Characteristics that Vary Continuously. Part I. Mendelian Genetics Background Information 1. Living things naturally exist in communities composed of some similar and some different kinds of organisms. Within populations of similar organisms, we see variations of certain traits expressed. Many traits are produced by a single gene.