BIOL 1107 1nd Edition Lecture 34Outline of Last Lecture I. Gene Pool II. Allele FrequencyIII. ExamplesOutline of Current LectureI. Hardy-Weinberg II. Non-random mating III. Changes in allele frequency (definitions)Current LectureI. Hardy-Weinberg - Hardy-Weinberg accurately predicts population if:o No mutationso Random mating o No gene flow o Natural selection - When expectations are NOT met o AA Aa aa (0.25) (0.5) (0.25) A = 0.5 a = 0.5 II. Non-random mating - Does non-random mating occur in humans? No- When expectations are NOT meto AA – 5,000 – 2,400 AA -- 2,600o Aa—10,000—5,000 Aa -- 5,000o Aa—5,000—2,600 aa – 2,400 20,000 10,000 10,000 larger populationThese 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.A = 0.5 0.49 sizesA = 0.5 0.51- When expectations are NOT meto AA – 2 – 0 AA -- 2o Aa— 6 -- 3 Aa -- 3o Aa— 2 —2 aa – 0 This is why Hardy-Weinberg A = 0.5 0.3 0.7 doesn’t work for small populations a = 0.5 0.7 0.3III. Changes in allele frequency - Genetic drif- change due to random event - Founder effect- the reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.- Bottleneck- happens after natural disaster - Migration- causes change in allele frequency that also interferes with Hardy-Weinberg - Fitness- likelihood of passing on genes to the next generation - Natural selection- the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to bethe main process that brings about evolution- Directional selection: a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. Under directional selection, the advantageous allele increases as a consequence of differences in survival and reproduction among different phenotypes. The increases are independent of the dominance of the allele, and even if the allele is recessive, it will eventually become fixed.- Stabilizing selection: opposite of disruptive selection. Instead of favoring individuals with extreme phenotypes, it favors the intermediate variants. It reduces phenotypic variation and maintains the status quo.- Disruptive selection: describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.- Q: John is studying lizards with a maximum lifespan of eight years. How long will it take for John to see these lizards evolve?- A: He could see evolution if he compared lizards from one generation to lizards from another generation in a period of environment flux- Q: Mosquitoes have heritable variation for insecticide resistance (amount andkind); however, all mosquitoes require standing water for the development ofoffspring. To which of the following control methods would the mosquitoes be least likely to develop resistance? - A: (1) & (3) -> see answers on elc
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