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B-SC: Students will demonstrate an understanding of the history of life on Earth.
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gene pool: combined genetic information of all members of a particular population relative frequency: # of times an allele occurs in a gene pool compared with the # of times other alleles occur
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In genetic terms, evolution is any change in the relative frequency of alleles in a population
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2 main sources due to sexual reproduction (homologous chromosome independently assort in meiosis)
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1. MUTATIONS +/- changes phenotype +/- changes fitness
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2. Gene Shuffling Cause of most heritable differences Humans have 8.4 million different combinations of genes
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When a single gene controls a phenotype There are only 2 alleles: dominant & recessive
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Natural selection on single-gene traits can lead to changes in allele frequencies which leads to evolution
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Controlled by 2 or more genes Each gene has 2 or more alleles
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3 different ways natural selection can affect phenotypes: 1. DIRECTIONAL SELECTION 2. STABILIZING SELECTION 3. DISRUPTIVE SELECTION
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When individuals at either end of the bell-shaped curve have an advantage the curve moves in direction of advantage
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When individuals near the mean of the graph have advantage (higher fitness) the bell shape becomes taller
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When individuals at both extremes have advantage (or middle has decreasing fitness)the middle decreases
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seen in small populations may see a particular allele producing more offspring than would happen by chance over time a series of chance occurrences can make an uncommon allele common
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when small sampling of large population colonizes new habitat & allele frequencies not representative of original population
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states that allele frequencies in a population will remain constant unless 1 or more factors cause those frequencies to change when allele frequencies remain constant population is said to be in genetic equilibrium
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1. Random Mating 2. Large Population 3. No Immigration or Emigration 4. No Mutations 5. No Natural Selection (all genotypes have same chance of survival)
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Classification systems used to name organisms & to group them in a logical manner. Linnaeus (Swedish botanist ) developed binomial nomenclature: 2 part name for every species (Genus species) Man: Homo sapiens
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TAXONOMY discipline of classifying organisms & assigning each organism a universally accepted name the study of evolutionary relationships among organisms PHYLOGENY
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TaxonomyPhyogeny
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diagram that shows evolutionary relationships among a group of organisms an evolutionary tree of life
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page 453 Hand in for grading
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