EEB 2245 Chapter Notes - Chapter 5: Three-Spined Stickleback, Linkage Disequilibrium, Overdominance

• School: UConn
• Department: Ecology and Evolutionary Biology
• Course: EEB 2245
• Professor: Dr Janine N. Caira and Dr. Paul Lewis

Document Summary

Chapter 5: the genetical theory of natural selection. The -hemoglobin locus is under balancing selection, which is selection that maintains genetic variation with a population; fundamentally different from selection on beneficial and deleterious alleles, which acts to remove genetic variation. Malaria is a disease caused by a protozoan parasite (plasmodium) that is transmitted by mosquitoes in tropical regions around the world. The -hemoglobin locus connection to malaria is the most famous example of overdominance, which occurs when the heterozygote has higher fitness than both homozygotes. Overdominance leads to the population that evolves to a stable polymorphic equilibrium, which means that both alleles are maintained. The evolutionary genetics of sickle-cell anemia have three general messages about evolution: overdominance maintains genetic variation, population genetic theory makes testable predicts about evolution, and humans (like all other species) are still evolving by natural selection.