Linda owns an orchard of orange trees, and she is worried because she notices that many of her orange trees are unhealthy. They
appear to have very little resistance to attack by a certain fungus that is destroying their leaves. She consults with some biologist friends, and they tell her that her orchard is threatened by low genetic diversity. How could she improve the ability of her orchard to resist disease in the future?
If there is low genetic diversity, she needs to introduce something into the system to increase the variation. I would suggest breeding the orange trees with other new orange trees to change the allele frequencies, which is called gene flow.
Likely the fungi are attacking them somewhere that they have decreased resistance, and if more alleles were introduced, there would probably be evolution towards a genotype that promotes defense against these fungi.
