BIOL 3350 1st Edition Lecture 13 Outline of Last Lecture I. Outcomes of Natural SelectionII. Selection in natural populationsa. ADH is Drosophilab. Desert sand and nearby ancient lava flowsIII. OverdominanceIV. Cystic FibrosisV. UnderdominanceVI. Mutation as a force of evolutionVII. Modeling mutationa. Irreversible mutationsb. Reversible mutationsc. EquilibriumVIII. Most mutation are deleteriousOutline of Current Lecture I. Maintenance of Deleterious Mutation: Sickle-Cell AnemiaII. Migration = Gene FlowIII. Nature of Gene FlowIV. Genetic Consequences of migrationV. Migration rate (m)VI. Lake Erie Water SnakesCurrent LectureI. Maintenance of Deleterious Mutation: Sickle-Cell Anemiaa. sickle-cell anemia is the result of a point mutation where a thymine has been exchanged for an adenineb. This is a missense mutations (non-synonymous)c. By just changing one base, the codon has been changed – changed glutamate to valined. This changes the structure of the hemoglobin molecule that makes it less able to carry oxygen – red blood cells collapse in on themselvesII. Migration = Gene Flowa. Migration in terms of evolutionary changes involved incorporation of new genes into a receiving populationb. There can be a change of allele frequencies in both populationsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.III. Nature of Gene Flowa. Zygotic gene flow – when an animal moves from one habitat to anotherb. Ex: mountain lions grow up and move thousands of miles to another habitatc. Gametic gene flow – haploid gametes moved. Ex: marine coral throughout their gametes all at one time to disperse theme. Integration of migrant alleles - Migration can act to conserve genetic variationf. Gene flow can act to increase the frequency of alleles much faster than mutationg. Migration allows for evolution to act at a much higher rateIV. Genetic Consequences of migrationa. Migration is homogenizing variability between populations- increases variability within a population but makes both populations more similar to each otherb. Slows down the rate at which populations because genetically differentiated form one anotherc. New combinations of pre-existing traits can be generated by recombination with introduced genotypesi. When mix two population, their genetic frequencies become very similar ii. Population 1 – allele A1 and A2 are fixed at firstiii. Population 2 – allele B1 and B2 are fixed at firstiv. Through recombination – the population have increased the variability of their genomes; migration can increase genetic variabilityv. Migration can cause evolutionary changed. Can cause deviations from HWE until new equilibrium is reachedV. Migration rate (m)a. m = the number of migrants per generation / the # of individuals on the island; thus, the proportion of the island population that is made up of migrantsVI. Lake Erie Water Snakesa. This is co-dominant situationb. Plain – homozygousc. Heavily banded – homozygousd. Intermediate banding pattern – heretozygouse. Scientists wanted to know if migration can impede natural selectionf. Mainland snakes are mostly bandedg. Island snakes are mostly solidh. A lot more plain snakes on the islandsi. More similarities with island populations to the mainland populations with the islands closest to the mainlandj. This difference is b/c the habitats on the mainland and islands are differentk. Island shores are sandy – plain snakes survived much betterl. Mainland shores are rocky – banded snakes survived
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