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Microevolution and macroevolution Microevolution is evolution that occurs within a population or a change in the gene pool over a succession of generations Macroevolution is evolutionary change on a grand scale, encompassing the origin of novel designs , evolutionary trends, adaptive radiation, and mass extinction O. Experiencing the Hardy-Weinberg Equilibrium formula. J. How do we know that a population is changing? Macroevolution novel designs like feathers & wings, upright posture in humans trends like increasing brain size in mammals adaptive radiation is seen in flowering plants *mass extinction like the dinosaurs Hardy-Weinberg Theorem Before we can look at microevolution we must consider the H-W theorem A few definitions first: Population- all the members of a single species occupying a particular area at the same time species- organisms that share a common gene pool, interbreed with one another gene pool- total of all the genes of all the individuals in a population P 394 for gene frequenciies in iText Hardy-Weinberg Theorem Describes a nonevolving population. It states that the frequencies of alleles and genotypes in a population’s gene pool remain constant over the generations unless acted upon by agents other than sexual recombination. So sexual shuffling of alleles due to meiosis and random fertilization have no effect on the overall genetic structure of a population. 5 conditions that must be met to maintain equilibrium population must be very large population must be isolated from others no mutations random mating must occur no natural selection can occur Causes of microevolution • genetic drift • gene flow • mutations • nonrandom mating • natural selection If any of these occur then equilibrium is NOT present in the population! Genetic drift- changes in a gene pool of a small population due to chance. 2 situations that can lead to genetic drift: 1. bottleneck effect- disasters such as earthquakes or floods reduce the population drastically, killing victims unselectively, reduces variability 2. founder effect-a small number of individuals colonize an isolated island, lake, or some other new habitat Gene Flow -population may gain or lose alleles by gene flow, genetic exchange due to the migration of fertile individuals or gametes between populations ex. – humans moving around the world Mutations -a change in an organism’s DNA Nonrandom mating or assortive mating individuals selecting mates because of a particular phenotype ex. cardinals with the brightest red feathers Natural Selection differential success in reproduction because an organism is more fit for their environment O. Getting the Hardy-Weinberg Equilibrium Formula. Write this down in your journal. Test on Evolution (14,15,16) on Wed.(if on field trip) or Thursday if going to be present Study Guide answers online Quiz answers online Study this weekend! wildflower population two colors of flowers A – pink, a – white 500 plants = 1000 genes 20 white plants = 40 a alleles the other 480 are pink = 320 are AA=640 A alleles 160 are Aa =160 A alleles, 160 a alleles So the frequency of gene A is 800/1000 = .8=80% the frequency of gene a is 200/1000 = .2 =20% p = frequency of gene A q = frequency of gene a p+q=1 If you consider genotypic frequencies AA = 320/500=.64=64% Aa = 160/500= .32=32% aa = 20/500=.04=4% Hardy-Weinberg equation: p2 + 2pq + (frequency of (frequency of AA genotype) Aa genotype) For wildflowers q2 = 1 (frequency of aa genotype) .64 + .32 + .04 = 1 Problem: Maple syrup urine disease (MSUD) is autosomal recessive and causes intellectual and physical disability, difficulty feeding, and a sweet odor to urine. In Costa Rica, 1 in 8000 newborns inherits the condition. What is the carrier frequency of MSUD in this population?