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EVOLUTION of POPULATIONS. B-SC: Students will demonstrate an understanding of the history of life on Earth. . defintions. gene pool : combined genetic information of all members of a particular population

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Evolution of populations

EVOLUTION of POPULATIONS

B-SC: Students will demonstrate an understanding of the history of life on Earth.


Defintions
defintions

  • 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



Sources of genetic variation
Sources of Genetic Variation frequency of alleles in a population

  • 2 main sources due to sexual reproduction (homologous chromosome independently assort in meiosis)


Sources of genetic variation1
Sources of Genetic Variation frequency of alleles in a population

  • MUTATIONS

    +/- changes phenotype

    +/- changes fitness


2 gene shuffling
2. Gene Shuffling frequency of alleles in a population

2. Gene Shuffling

  • Cause of most heritable differences

  • Humans have 8.4 million different combinations of genes


Single gene traits
Single Gene Traits frequency of alleles in a population

  • When a single gene controls a phenotype

  • There are only 2 alleles: dominant & recessive



Polygenic traits
Polygenic Traits in allele frequencies which leads to evolution

  • Controlled by 2 or more genes

  • Each gene has 2 or more alleles


Natural selection on polygenic traits
Natural Selection on Polygenic Traits in allele frequencies which leads to evolution

  • 3 different ways natural selection can affect phenotypes:

  • DIRECTIONAL SELECTION

  • STABILIZING SELECTION

  • DISRUPTIVE SELECTION


Directional selection
DIRECTIONAL SELECTION in allele frequencies which leads to evolution

  • When individuals at either end of the bell-shaped curve have an advantage the curve moves in direction of advantage


Stabilizing selection
Stabilizing Selection in allele frequencies which leads to evolution

  • When individuals near the mean of the graph have advantage (higher fitness) the bell shape becomes taller


Disruptive selection
Disruptive Selection in allele frequencies which leads to evolution

  • When individuals at both extremes have advantage (or middle has decreasing fitness)the middle decreases


Genetic drift
Genetic Drift in allele frequencies which leads to evolution

  • 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


Founder effect
Founder Effect in allele frequencies which leads to evolution

  • when small sampling of large population colonizes new habitat & allele frequencies not representative of original population


Hardy weinberg principle
Hardy-Weinberg Principle in allele frequencies which leads to evolution

  • 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


5 conditions necessary to maintain genetic equilibrium
5 conditions necessary to maintain genetic equilibrium in allele frequencies which leads to evolution

  • Random Mating

  • Large Population

  • No Immigration or Emigration

  • No Mutations

  • No Natural Selection (all genotypes have same chance of survival)


Hardy weinberg equation
Hardy-Weinberg Equation in allele frequencies which leads to evolution


Classification
CLASSIFICATION in allele frequencies which leads to evolution

  • 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


Evolutionary classification
Evolutionary Classification in allele frequencies which leads to evolution

TAXONOMY

PHYLOGENY

  • discipline of classifying organisms & assigning each organism a universally accepted name

  • the study of evolutionary relationships among organisms


Taxonomy in allele frequencies which leads to evolution

Phyogeny


Cladograms
Cladograms in allele frequencies which leads to evolution

  • diagram that shows evolutionary relationships among a group of organisms

  • an evolutionary tree of life


Quick lab
Quick Lab in allele frequencies which leads to evolution

page 453

Hand in for grading


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