Bio A02 Final Study Notes

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University of Toronto Scarborough
Biological Sciences

Biology FINALS Study Notes CHAPTER 22: THE MECHANISM OF EVOLUTION CHARLES DARWIN o Species change over time o Process that produce these changes is natural selection o Offspring not identical o INDIVIDUALS DO NOT EVOLVE. POPNS DO !! o No actual experiments just observations o Popn genetics help support arguments ALFRED RUSSEL WALLACE also proposed natural selection hypothesis MALTHUS argues: since popn growth > food production famine; thus, unchecked pop. Growth = famine o Darwin: death rates must be high NATURAL SELECTION: differential contribution of offspring to the next gen. by various genetic types belonging to same popn. POPULATION: group of individuals of a single species that live and interbreed in a particular geographic area at the same time For popn to evolve must have heritable genetic variation popn evolves when individual w diff phenotypes survivereproduce at diff. rates ADAPTATION: both processes by which characteristics appear to be useful to the owner that evolves AND the characteristics themselves GENE POOL: sum of all alleles found in a popn CHARACTERS: feats. Of a phenotype ie. eye colour TRAIT: specific form of a character iebrown eyes HERITABLE TRAIT: characteristic of an organism that is partly determined by its genes www.notesolution.comPOPN GENETICS 3 MAIN GOALS: 1. explain origin & maintenance of genetic variation 2. explain patters & organization of genetic variation 3. understand mechanisms that cause changes in allele freqs in popns rediscovered from Mendels work MENDELIAN POPN: local popn of individuals belonging to same species and exchanging genes with one another; describes genetic structure FREQUENCY: proportion of allelegenotype in gene pool HARDY-WEINBERG EQUILIBRIUM: eqn describes a model where allele freqs dont 2 2 change across gens. And genotype freqs can be predicted p + 2pq + q =1 ; FACTORS THAT MUST BE PRESENT : mating is random population size is infinite no gene flow no mutation natural selection MECHANISMS OF EVOLUTIONARY CHANGE: 1. mutations create genetic variation 2. gene flow change allele freqs 3. genetic drift causes BIG changes in SMALL popns popn bottlenecks: only few survive a random event founder effect: establishing a new popn in new region 4. non-random mating FITNESS: reproductive contribution of a phenotype to new gens relative to contribution of other phenotypes; determined by average rates of survival and reproduction of one with that phenotype
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