Variation is the differences between individuals of the same species, caused by genetic and environmental factors. Surveys into variation give data that are continuous, which means to come in a range, ...

The proportion of people with different blood groups in the population A characteristic of any species with only a limited number of possible values shows discontinuous variation. Here are some ...

ON September 24, some years ago, I collected at Mesilla, New Mexico, four examples of a wild bee of the genus Epeolus, the species being probably identical with Epeolus bardus of Cresson. In every one ...