Populations Genetics of Humans

Christine Langhoff

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Essay from the year 2002 in the subject Biology - Genetics / Gene Technology, grade: 2.1 (B), Oxford University (New College), la...

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Essay from the year 2002 in the subject Biology - Genetics / Gene Technology, grade: 2.1 (B), Oxford University (New College), language: English, abstract: The aim of population genetics is to model the dynamics of evolutionary change within and between populations i.e. a group of individuals who exist together in time and space and are capable of interbreeding. In human DNA approximately 0.08% of the nucleotide base pairs varies among individuals and thus populations genetics has been trying to establish why this is so. Four basic evolutionary forces responsible for genetic diversity in populations have been identified: mutation, natural selection, genetic drift and gene flow. Mutations are copying errors during DNA replication and transcriptions, which introduce new alleles into the population. Natural selection is the differential transmission of alleles into the next generation due to the consequences of functional differences on an individual's survival and reproductive success. Genetic drift is the differential transmission of alleles into the next generation as a result of random sampling and has the greatest potential impact in small populations. Gene flow spreads alleles from one population into another via migration, making them more genetically similar to each other, and countering genetic differentiation by drift. I am going to examine the contribution of genetic drift, gene flow and natural selection to the levels of diversity and composition of genetic polymorphisms in different human populations. Further I am going to examine why some populations have greater diversity than others and compare the patterns of genetic diversity of humans and chimpanzees.