BIOLOGY 1M03 Chapter 15: Chapter 15- Human Genetic Diveresity.docx
8 Sep 2014
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Damage to this gene prevents normal development of some psychological machinery necessary for language. Mutation can maintain deleterious genes in populations, but only at a low frequency. Selection-mutation balance selection can maintain variation within populations if heterozygotes have higher fitness than either of the two homozygotes. Causes of genetic variation selection that favours different genes in different environments creates and maintains variation among groups. 2 example: hemoglobin: hemoglobin s is most common in tropical africa, around mediterranean. Earth example: mitochondrial dna: indicates human species underwent a worldwide population expansion about 100 000 years ago example: invention of agriculture, led to expansions of farming peoples from middle east into europe, from. Sforza (stanford university) argued that patterns of genetic variation preserve a record of these expansions: human populations expand and move away from each other. 3: as they move farther apart, they become more genetically isolated from one another and accumulate genetic differences.
