Viable offspring offspring capable of reproduction Population geographically

Viable offspring offspring capable of reproduction

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Viable offspring= offspring capable of reproduction - Population= geographically isolated group of individuals from same species Populations of organisms evolve as a result of environmental changes - Some alleles confer survival or reproductive advantage to an individual 12.4 Scientists can test evolution - Counting alleles allows you to calculate their frequencies - Hardy-Weinberg equilibrium= hypothetical situation where allele frequencies do NOT change between generations - Allele frequencies: p+q=1 - p= frequency of dominant allele - q= frequency of recessive allele - Genotype frequencies: p 2 +2pq+q 2 =1 - p 2 = frequency of homo. dom. Genotype - 2pq= frequency of het. genotype - q 2 = frequency of homo. rec. Genotype - Compare to real populations to see if evolution is occuring Hardy-Weinberg equilibrium Assumptions - Natural selection does not occur - Mutations do not occur - Population is infinitely large - Individuals mate randomly - Individuals do not migrate Allele frequencies always change - In real populations, the assumptions of Hardy-Weinberg are always violated-- evolution is occuring! 12.5 Natural selection can shape populations
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- Different types of natural selection have distinct effects on the phenotypes in a population - Directional selection= favors one phenotype over another - Disruptive selection= favors extreme phenotypes (rare) - Stabilizing selection= favors intermediate phenotypes (most common) 12.6
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  • Spring '16
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