Evolution Notes 3/10-3/12
Evolution Notes 3/10-3/12 BIOL 337
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This 4 page Class Notes was uploaded by Carolina Arreola on Saturday March 14, 2015. The Class Notes belongs to BIOL 337 at San Francisco State University taught by Routman in Spring2015. Since its upload, it has received 95 views. For similar materials see Evolution in Biology at San Francisco State University.
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Date Created: 03/14/15
Evolution Notes 31015 Selection amp Gene Flow Gene ow spreads alleles around and selection just increases the frequency of the dominant allele Suppose there are 2 different populations one population favoring Cap A39s and the other population favoring little a39s This is called local adaptation adapting to your local environment How does gene ow interact with this Selection trying to increase the frequency of a particular allele and gene ow decreasing it It39s harder to adapt to your local situation of gene ow is occurring and migrants are constantly adding a different allele In the less polluted areasless industrial areas the White moths are more prevalent and vice versa with the dark moths Bison Beulariamoths have a higher gene ow because they y around a lot more The ability to adapt to local places is inhibited by gene ow Factors that affect evolution 1 PhenotypeEnvironment Interaction Ecology How phenotypes interact with the environment to determine an individual39s tness 2 Genetic Architecture Genetic architecture refers to the genetic quotmake upquot of the phenotype such as the number of loci and the number of alleles per locus How many genes are affected How do these alleles interact with one another to form a particular phenotype this is called gene action Additive Gene Action A situation in which the effect of an allele is independent of it39s genetic context genetic context just means the other alleles that are there When this is the case you can predict the phenotype by adding up the different alleles very predictable AA Aa aa ex 1 07 04 gt If the heterozygote is half way we know it is additive gene action A 05 a 02 Heterozygote is equal to 050207 NonAdditive Gene ActionThe effect of an allele DEPENDS on it39s genetic context Dominance Refers to nonadditive gene action Within the same locus AA Aa aa Dominance W 6 6 9 Complete W 6 7 9 Partial W 6 10 6 Over W 6 4 6 Under Epistasis sub category of nonadditive gene action The fetal hemoglobin is turned on in the fetus and then gets shut off at birth A mutation in the fetal hemoglobin locus gets continually expressed in the adult creating an adaptation to malaria 3Population Structure The factors that determine how gametes come together to form zygotes Many factors affect this such as Population Size N Mating system will determine if two Cap A39s will get together more less frequently Geographic structure of populations 4 History It39s the history of the population that has set up the current conditions Complex traits traits or phenotypes that are affected by multiple loci and or the environment The eld that studies complex traits is called quotQuantitative Geneticsquot We study complex traits by studying the frequency of those traits in the population we will study traits that have a continuous distribution Mm Frequency in population XAxis Traits Look Ilma39s graph for details 10 75 5 25 O 510105 Thursday March 12 2015 Evolution Notes 3 types Of SGIGCtiOH Graphs on the right describe what the selection does to a trait and the graph on the left is what the selection IS Directional Selection When one extreme of a phenotype is higher in fitness than the rest of the phenotypes The variance of the parent generation will be greater or equal to the offspring generation Mp Mean of parental generation 2 Mean of Offspring Mo Fitness Frequency Trait Trait Stabilizing Selection When the mean phenotype has the highest fitness Individuals who have a phenotype that is higher or lower than the mean have lower fitness lt Mean of Offspring Fitness Frequency lt Mean of Parents Trait Trait Disruptive Selection When individuals with the mean trait value have lower fitness Not very common lt Mean of Parents Fitness Frequency lt Mean of Offspring 1 Trait Trait Thursday March 12 2015 Truncation Selection Atype of selection that divides the population into breeders and non breeders based on their phenotype Mp Mean of Parents 5g Threshold 7g Ms 9g lt Mp Fitness Frequency lt Ms green lt Threshold Trait ltMp TraIt Selection Differential SMsMp 9g5g4g lt This is the difference between the average phenotype in comparison to the rest of the population Response to Selection R R MoMp RS hA2 Heritability hA2 Phenotypic similarity between parents and offspring on avaerage in a population Didn39t get the notes for the last 10 minutes of class
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