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Chapter 6

BIOL150 Chapter Notes - Chapter 6: Allele Frequency, Genetic Drift, Mathematical Proof

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Rebecca Rooney

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Chapter 6: Hardy-Weinbery Equilibrium and exceptions
6.1 Evolutionary Processes
-Natural selection only evolutionary process causes adaptations bcs only one in which changes in allele frequency
between generations reflects differences in the relative fitness of individuals in a population
-not all phenotypic traits represent adaptations
-Evolutionary processes which may act at the same time with natural selection, or in the absence
Genetic drift
Gene flow
Non-random mating
-Hardy-Weinbery principle: has mathematical proof that allele and genotype frequency stays unchanged in sexually
reproducing populations if the following conditions are met:
1. No natural selection, doesn't occur
2. low mutation rate
3. large population due to which genetic drift not a factor
4. no net movement of individuals
5. random mating
-Overall, no evolutionary change occurs strictly as a result of sexual reproduction.
-These conditions are very less likely to be met because natural selection does occur, mutations do happen, populations
can be small, individuals move between populations, and mating not always random. Therefore, any of these can change
the allele and genotype frequency.
Mutations: heritable change in the structure of genes and chromosomes
-mutations are ultimate source of genetic variation upon which natural selection acts
-term refers to the process of changing the material or already changed, both.
-Mutation affected by many factors: one of them being UV radiation
-a mutation can be beneficial or harmful or even can have no effect, neutral.
-a mutation that may be fit for one environment may not be for the other
-harmful mutations don't let the being survive for too long
-natural selection gets rid of the deleterious alleles from the gene pool, leaving behind the alleles that don't effect
reproduction, survival, ability to grow.
-mutation alters allele frequencies
Gene drift: changes in allele frequencies that occur in small populations as a result of chance
-allele recombination is random, probability plays a role in sexual reproduction
-few offspring's means that not all the parents alleles are passed on to the children, offspring's represent only a subset
of parents alleles.
-evolutionary equivalent of sampling error, with each successive generation representing only a subset of the gene pool
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