We can divide variation into two types.
Continuous variation or discontinuous variation.
I hope by now that we all now that there is a big amount of variation between the same species and between different species.
Continuous variation is where there is a complete range of differences example height. Humans are not either short or tall, they can be anything in between. There is a continuous range of heights. If you drew a graph of this it would be a normal distribution curve. Characteristics that show continuous variation are often controlled by both genes and the environment. Example, you may inherit the alleles that may make you tall but unless you have the correct balanced diet you might not. If you don't grow tall, but you could have then this is called an Acquired characteristic. Acquired characteristics are caused by the environment and so are cause environmental variation between organisms. Makes sense to me.
Discontinuous variation is where there is a definite fixed value. You are either one thing or another. Your blood group is an example of discontinuous variation. You are one of 4 groups, A, B, AB or O. That's it - you must be one of those 4 goups and not nearly one or have a bot of 2 or ........ . You could draw this as a barchart. Discontinuous variation is usually caused by changes in the DNA so it is called Genetic variation.
