Discussion Topic 1

Natural Selection

A novel fungicide is introduced and widely applied to cereal crops. After five years, resistant genotypes of the fungal pathogen are detected at a frequency of about 1%; resistance is widely distributed across the pathogen’s range. Within two years, these have become so common that the fungicide becomes worthless.

Explain how this pattern can be explained by the basic features of natural selection. Include in your answer:

• A brief description of what natural selection is.
• The conditions that must be met in order for natural selection to occur.
• How natural selection explains the scenario above.

Discussion Topic 2

Mechanisms of Evolutionary Change

This unit we are learning that there are several mechanisms that lead to evolutionary change within a population or species: mutation, migration, genetic drift, non-random breeding and natural selection.

1. What is meant by “evolutionary change”; meaning what is it and how would you know when it has occurred?
2. Select two of the mechanisms listed above and explain how each can lead to evolutionary change as defined in Q#1. Be specific and use an example of each.