Hardy Weinberg TheoremAllele frequencies in a population will remain constant between generations if only Mendelein segregation and recombination are at work-unrealistic conditions (populations change)need:- Large pop. Szno migrationno mutationsno natural selectionrandom matingMICROevolution: allele frequencies change through time-genetic drifChanges in allele freq due to chance (rand change), MOST sig. in SMALL POPULATIONS, allele freq. fluctuates between gen.>>>can lead to ALLELE FIXATION (loss of an allele from a population)BOTTLENECK EFFECT: only a few of the whole population surviveFOUNDER EFFECT: few members go to a new isolated population-natural selectionResults in alleles being passed to offspring in disproportionate numbers to the frequencies in parental generationleads to change in allele freq between generations (EVOLUTION)only acts on genetic variation when expressed as the phenotypeaccumulates and maintains favorable genotypes in populationsif environment changes, new set of phenotypes is now favorableONLY PROCESS OF MICROEVOLUTION THAT IS ADAPTIVEdirectional, stabilizing, diversifying/disruptive, balancing (heterozygote, negative-frequency-dependent)sexual reproduction INCREASES GEN DIV WITHIN A POPnatural selection works on that diversity which REDUCES PHENOTYPIC DIVERSITY-migration (gene flow)-mutationWhat mechanisms preserve genetic diversity?diploidyheterozygote advantageneutral variationSexual reproduction increases genetic diversity in the next generation (within a population)Natural selection works on the diversity and reduces PHENOTYPIC diversityWhy natural selection can’t make “perfect” organismshistorical constraints, adaptations=compromises, chance+nat sel, selection can only EDIT existing variationsWhat is gene flow?the movement of alleles into or out of a populationwhat evolutionary mechanism causes gene flow between two populations?migrationPossible outcomes of genetic drift?Fixation or loss of an alleleSampling error=small when sample size is largeFounder effect and the bottleneck effect are both examples of how ______ ________ can rapidly alter allele frequencies when the size of a population dramatically decreasesA. migrationB. Gene flowC. Genetic drifD. Natural selectionWhat is the frequency of an allele that has been eliminated in a population?0NEUTRALWhen mating is __________ inidividuals choose their mates without regard for their genotypes and phenotypesRANDOM Genetic drift can promote __________ variation, which are changes in genes and proteins that do NOT affect reproductive success.Which type of natural selection favors individuals with an extreme phenotype?directionalstabilizingdiversifyingbalancingWhich type of natural selection favors individuals with an intermediate phenotype?directionalstabilizingdiversifyingbalancingWhich type of natural selection favors the survival of more than 2 genotypes?directionalstabilizingdiversifyingbalancingWhat type of selection favors the survival of two or more different genotypes that produce different
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