Natural selection is the directional force of evolution and is known to have affected the genetic structure of our species. The classic example of selection involves adaptations in the hemoglobin genes of humans created to combat malaria parasites. The most widely known adaptation is the sickle cell hemoglobin. Many primates other than humans harbor similar malaria parasites. One such primate is the orangutan, an Asian ape. The main hypothesis of this study is that the alpha globin genes of orangutans are under natural selection and adaptations to malaria. This is significant because if orangutan alpha globin genes have evolved by natural selection, malaria may be an important selective pressure in primates other than humans. By extension, malaria may have been a major selective force in the lives of early hominids such as Australopithecus. Large-bodied predators are often considered to be selective agents among apes, but microscopic "predators" may in fact have had larger effects.

To test this hypothesis, DNA sequence data will be generated for two genes, alpha-2 globin and Dmd, from a large number of orangutans. Different measures of genetic diversity will be calculated from these two genes, which will be compared and contrasted to one another. The Dmd gene has been shown not to be influenced by natural selection in humans and will therefore be an index of non-selective evolution. If the diversity at the two genes is significantly different, natural selection will be inferred to be acting at the alpha-2 globin gene.

The data collected will also be used to make inferences about orangutan population history and inform conservation efforts. Some estimations will be population age, population size, migration rates, and mutation rates. These parameters will then be compared to published comparable estimates for modern humans and chimpanzees, enabling direct comparisons among the population histories of these primates

National Science Foundation (NSF)
Division of Behavioral and Cognitive Sciences (BCS)
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Mark L. Weiss
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Harvard University
United States
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