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genetics kaht 2012
genetics kaht 2012

... also separate from one another. As a result, each sex cell ends up with one form of a gene for each trait that an organism shows. ...
Lecture 14 pdf - Institute for Behavioral Genetics
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... 2. Random mating. If individuals pick mates with certain genotypes, or if inbreeding is common, the mixing of gametes will not be random and genotype frequencies will change. 3. No natural selection. Differential survival or reproductive success among genotypes will alter allele frequencies. 4. Extr ...
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... Meiosis – Two successive divisions forming four haploid cells with ¼ the size as the original cell. Meiosis reduces chromosome number by half (2nn) to maintain the appropriate number of chromosomes for sexual reproduction. Results in gamete formation and introduces genetic variation (recombination) ...
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... 2. How do mutations change populations over time? a. Most mutations are harmful and cause species to become extinct b. Most mutations cause abnormal disease in species c. Mutations generally have no effect on a population since they are simple changes in DNA d. Mutation can produce adaptations in or ...
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... A maximum likelihood estimate of a parameter θ is the estimate of θ that maximizes the likelihood function. This provides an estimate of θ that “best explains” the observed data in some sense. For our example, we want to find the pAA and pBB that maximizes L(pAA,pAB). Sometimes it is possible to det ...
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... – Insecticides have been used to target mosquitoes that carry West Nile virus and malaria – Alleles have evolved in some populations that confer insecticide resistance to these mosquitoes – The flow of insecticide resistance alleles into a population can cause an increase in fitness ...
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... What was missing from Darwin’s explanation was an understanding of inheritance that could explain how chance variations arise in a population while also accounting for the precise transmission of these variations from parents to offspring. Just a few years after Darwin published The Origin of Specie ...
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Genetic drift



Genetic drift (or allelic drift) is the change in the frequency of a gene variant (allele) in a population due to random sampling of organisms.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces. A population's allele frequency is the fraction of the copies of one gene that share a particular form. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation.When there are few copies of an allele, the effect of genetic drift is larger, and when there are many copies the effect is smaller. In the early twentieth century vigorous debates occurred over the relative importance of natural selection versus neutral processes, including genetic drift. Ronald Fisher, who explained natural selection using Mendelian genetics, held the view that genetic drift plays at the most a minor role in evolution, and this remained the dominant view for several decades. In 1968, Motoo Kimura rekindled the debate with his neutral theory of molecular evolution, which claims that most instances where a genetic change spreads across a population (although not necessarily changes in phenotypes) are caused by genetic drift. There is currently a scientific debate about how much of evolution has been caused by natural selection, and how much by genetic drift.
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