Jones & Bartlett Publishers
by Chapter:
Evolution Links |
||
|
Chapter 22 - Changes in Gene Frequencies
Balanced Polymorphism -- Sickle Cell and Malaria. A classic example of how finely tuned relationships can be is the case of tolerance to malaria of heterozygous individuals with a single mutation in the gene for hemoglobin. Homozygous individuals for this mutation have a serious condition involving pleiotrophic effects (see Chapter 10 of Evolution, 3/e). What is sickle cell anemia and how does distribution of the mutation’s frequency relate to incidence of malaria? How can this be explained?
(The site will open externally in a new window) Mimicry is the evolution of like forms between separate species. There are various types of mimicry and the evolution of these conditions is a powerful inference of the effects of natural selection. Many are familiar with mimicry between the monarch butterfly and the viceroy butterfly. Are there other examples of mimicry? Might mimicry evolve in animals other than insects?
(The site will open externally in a new window) Basic modes of natural selection (stabilizing, directional, disruptive) lead to changes in shape of distributions of characters in populations. Classifying specific cases to these modes helps to illustrate how evolution can have multiple effects upon populations. How do natural, sexual, and artificial selection differ? How are they the same? Are there examples for these modes of selection?
(The site will open externally in a new window) |
||
For Technical Help