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Evolution of Populations
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DO NOW Is evolution random or non-random? Be prepared to discuss.
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DO NOW (1)Hand in Chapter 22 Homework and signed contract (place in folder marked with your class period) (2) Write your name and class period on your lab supply item and place it in the corner of the classroom in the spot marked with your class period (3) Put away bags and cell-phones – we will begin with the quiz
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Selection In Action Peppered moths Darwin’s finches Antibiotic-resistant bacteria Lactose tolerance in humans
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Modern Evolutionary Synthesis Darwin’s theory of evolution by natural selection lacked an explanation for the basis of heredity. Genetics helped explain this, creating a synthesis between the idea of Darwinian selection and Mendelian genetics.
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Evolution of Populations Population: localized group of individuals belonging to the same species Evolution happens on a larger level than the individual organism – evolution occurs at the level of populations.
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Population genetics: the study of genetic variability within populations Gene pool: combined aggregate of genes in a population at any one time Species: a group of populations that have the potential to interbreed and produce fertile offspring in nature
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Hardy-Weinberg principle states that allele and genotype frequencies will remain constant from generation to generation in the absence of other evolutionary influences
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Hardy-Weinberg Theorem Assumptions 1.Very large population size 2.No migration 3.No net mutations 4.Random mating 5.No natural selection
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Mechanics of Hardy-Weinberg p = allele 1 q = allele 2 p + q = 1 (100% of population) Note: This is for calculating frequencies of genotypes when there are only 2 alleles for a single locus
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Punnett Square for Hardy-Weinberg Females A (p)a (q) Males A (p)AA (p 2 )Aa (pq) a (q)Aa (qp)aa (q 2 ) p 2 + 2pq + q 2 = 1
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Microevolution
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Bottleneck Effect
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Genetic Drift
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Founder Effect
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Steps of The Scientific Method
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Experimental Method Only one variable must be tested at a time, with the result being compared against a control Independent and dependent variable
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Genetic Variation Within Populations Polymorphism Gene diversity Nucleotide diversity
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Geographic variation Cline
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Maintaining Genetic Variation In Populations Diploidy Heterozygote advantage Frequency-dependent selection Neutral variation
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Modes of Selection
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Intrasexual selection Direct competition among individuals of the same sex
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Intersexual selection Also known as mate choice, when members of one sex are choosy in selecting mates of opposite sex
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Balanced polymorphism Ability of natural selection to maintain stable frequencies of two or more phenotypic forms
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Heterozygote advantage When individuals that are heterozygous at a particular locus have a greater survivorship and reproductive success
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Frequency-dependent selection Survival and reproduction of any one morph declines if the phenotypic form becomes too common
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