Lecture 3 bild3

Lecture 3 bild3 - o o P =f(A o Q=f(a o Hardy Weinberg...

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Lecture 3 P^2 + 2pq +q^2 =1 p+q=1 o AA Aa aa o P =f(A) o Q=f(a) o Hardy Weinberg Equilibrium (non-evolving) o 1. Allele frequency genotype frequency o 2. Genotype frequency allele frequency o 3. Change in allele frequency given selection o 4. Testing a real population if its in HWE or not Genetic drift o Sampling error Chances differences between a sample and the entire population Smaller sample –more sampling error o The bottleneck effect A sudden change in the environment may drastically reduce the size of a population The gene pool may no longer be reflective of the original population’s gene pool o The founder effect Occurs when a few individuals become isolated from a larger population as when a few individuals colonize an island Can affect allele frequencies in a population Gene flow o Consists of the movement of alleles among populations o Alleles can be transferred through the movement of fertile individuals or gametes o Gene flow tends to reduce differences between populations over time o Gene flow is more likely than mutation to alter allele frequencies directly o Gene flow can decrease the fitness of a population Mal adaptation In bent grass, alleles for copper tolerance are beneficial in populations near copper mines, but harmful to populations in other soils Windblown pollen moves these alleles between populations The movement of unfavorable alleles into a population results in a decrease in fit between organism and environment o Gene flow can increase the fitness of a population 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 o Gene flow is a homogenizing force
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Mixes things up until allele frequencies are the same across populations Summary Mutations are the ultimate source of genetic variability Recombination and sexual reproduction result in novel genetic combinations The Hardy-Weinberg law predicts stable allelic and genotypic frequencies in certain conditions Deviations from Hardy-Weinberg equilibrium are caused by mutation, migration, nonranmdom mating, small population size and selection. Summary 2 Selection and genetic drift tend to0 reduce genetic variation Mutation, diploidy, neutrality, gene flow, and balancing selection can maintain genetic variation in a population. Speciation Creation and maintenance of various species through evolutionary processes Species concepts Mechanisms of genetic isolation o Allopatric o Sympatric o Parapatric Mechanisms of genetic divergence o Drift o Natural selection o Sexual selection Secondary contact o Reinforcement o Hybridization Are species real entities or a product of the human desire to pigeonhole or classify How do we define them
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Lecture 3 bild3 - o o P =f(A o Q=f(a o Hardy Weinberg...

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