3.29 Species Variation

3.29 understand that variation within a species can be genetic, environmental or a combination of both

Variation = differences in phenotypes Note: these can be measured and shown in a graph

Initially you must understand that a population’s phenotypes are controlled by their Genotype and/or the Environment they live in.

1. Genotype

Some phenotypes are controlled by purely a variation in the individual’s genotype, and their environment has no control in the phenotype whatsoever. An example of this would be blood group. Notice that this creates discontinuous data (i.e. this or this or this etc.)

2. Genotype + Environment

In some cases the variation of a population’s phenotype is controlled by a combination of their genotype and their environment. Height is a good example phenotype for this; if your parents are reasonably tall, your genotype may make you tall, and your changes in your diet (environment) can also have an effect. This produces a continues scale of variation (i.e. between this point and this point)

3. Environment

There can be variations in a population that are purely controlled by the environment, such as your home language; there are no genotypes to control the languages you can speak, simply how you are brought up controls this. This therefore cannot be inherited