Evolution
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Evolution. 3/27/12. Objective: Introduce origins theories Do Now: Hand in popular science questions Do Later: Read sections 13.1-3. Diversity of life. Estimated 10 million species on earth Phylogenetic trees show relationships. Origins Theories. Lamarck Spontaneous generation

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3 27 12
3/27/12

  • Objective: Introduce origins theories

  • Do Now: Hand in popular science questions

  • Do Later: Read sections 13.1-3


Diversity of life
Diversity of life

  • Estimated 10 million species on earth

    • Phylogenetic trees show relationships


Origins theories
Origins Theories

  • Lamarck

    • Spontaneous generation

      • Simple organisms are more recent

      • Complex organisms are older, gained complexity over time

    • Theory of Acquired Characteristics

      • Characteristics acquired by parents get passed on to offspring



Origins theories2
Origins Theories

  • Catastrophism

    • Rapid, catastrophic events shape geology and extinction

  • Gradualism

    • Slow change of geologic features and life forms over time

Georges Cuvier

Charles Lyell


Origins theories3
Origins Theories

  • “Descent with modification”

    • Species have natural variation

    • Certain characteristics are favored over time


Natural selection
Natural Selection

  • Condition 1: Variation

    • Populations must have variation in traits for selection to occur


Natural selection1
Natural Selection

  • Condition 2: Competition

    • “Survival of the fittest”

      • Scarce resources, avoiding predators, etc.

    • Only the best adapted species survive


Natural selection2
Natural Selection

  • Condition 3: Inheritance

    • Favorable traits are passed on to offspring

    • Genetic inheritance


Natural selection3
Natural Selection

  • Theory of Natural Selection

    • Heritable traits that confer an advantage in survival and reproduction will increase in frequency in a population.

    • Gradually a population will change as a result of natural selection.


Artificial selection
Artificial Selection

  • Selection performed by a conscious agent.

    • Dog breeding

    • Crop selection


4 2 12
4/2/12

  • Objective: To examine speciation and evidence for natural selection

  • Do now:

    • Discuss with a partner – What is a species?

    • Come up with a definition in pairs

  • Do later: Read 13.5-6 in text

    • On separate paper: Pg. 275 #1, 3-7, 12


Species
Species

  • A species is a group of organisms that are able to interbreed and produce fertile offspring.

Mules are the offspring of a male donkey and a female horse. They are sterile.


Hybrid species
Hybrid Species

Zebra + horse  zebroid (sterile)

Tiglons can occasionally reproduce with difficulty.


Speciation
Speciation

  • How do new species come to be (speciation)?

    • 1) Population is separated

    • 2) Each population changes due to natural selection

    • 3) Differences accumulate to make interbreeding impossible


Evidence for natural selection
Evidence for Natural Selection

  • Biogeography

    • Geographic distribution of species

Why do all marsupials live in Australia?


Evidence for natural selection1
Evidence for Natural Selection

  • Homologous Structures

    • Anatomically similar structures in groups of related organisms

    • May serve different functions


Evidence for natural selection2
Evidence for Natural Selection

  • Molecular Biology

    • DNA sequencing can confirm the relationship between two species

      • Few genetic differences = closely related

      • Many genetic differences = distantly related

98.5% similar


4 3 12
4/3/12

  • Objective:

  • Do Now:

    • Pick two evidences for evolution and explain (in writing) how they show “descent with modification”. (3 minutes)

  • Do Later:


Evidence for natural selection3
Evidence for Natural Selection

  • Vestigial Structures

    • Structure that is no longer used in an organism

    • Artifact of a useful structure in an ancestor


Vestigial structures
Vestigial Structures

  • Whale pelvis


Vestigial structures1
Vestigial Structures

  • Human Coccyx


Vestigial genes
Vestigial Genes

  • Vestigial genes – organisms have genes in their DNA that are no longer active

  • Chicken teeth

    • Genes for teeth can be turned back on in chickens


Transitional forms
Transitional forms

  • Fossil evidence of an intermediate form between a present day species and an ancestor.


Transitional forms1
Transitional Forms

  • Archaeopteryx – transitional form between dinosaurs and modern birds

Archaeopteryx – between dinosaurs and aves (birds)


Transitional forms2
Transitional forms

  • Tiktaalik

    • Transitional form between aquatic and land animals

    • “lobe finned fish”


Transitional forms3
Transitional Forms

Basilosaurus – intermediate between land mammals and whales

whale


Comparative embryology
Comparative Embryology

  • Early stages of development are similar across the animal kingdom


4/6

  • Objective: To discuss pesticide and antibiotic resistance

  • Do later: Popular Science – Pesticide and antibiotic resistance


Pesticide resistance
Pesticide Resistance

  • Application of pesticides selects for pesticide resistance

Red = pesticide resistant

White = wild type (‘normal’)


Pesticide resistance1
Pesticide Resistance

  • Colorado Potato Beetle

    • Agricultural pest

    • Resistant to all major classes of insecticides


Pesticide resistance2
Pesticide Resistance

  • Can you think of any ways to combat pesticide resistance?

    • Pesticide rotation

    • Natural predators

    • Diversifying crops

The fungus Beauveriabassianais toxic to many beetles but non-toxic to humans

Diversifying crops can limit the spread of pests


Antibiotic resistance
Antibiotic Resistance

  • Use of antibiotics selects for antibiotic resistant bacteria.

    • Drug resistance evolves over time.


Antibiotic resistance1
Antibiotic Resistance

  • Methicillin-Resistant Staph Aureus (MRSA)

    • “Staph infection”

    • Resistant to many classes of anti-staphylococcus drugs


Antibiotic resistance2
Antibiotic Resistance

  • Extensively Drug Resistant Tuberculosis (XDR-TB)

    • Lung disease

    • Resistant to three or more major anti-TB drug classes

    • High mortality (50% +)


Antibiotic resistance3
Antibiotic Resistance

  • Solutions?

    • Limit prescription of antibiotics

    • Limit use of antibiotics in agriculture

    • Use full prescriptions

    • Vary prescriptions


4 17 12
4/17/12

  • Objective: To examine varieties of selection

  • Do Now:

    • With a partner, describe the differences between natural selection, artificial selection, and sexual selection. Provide an example of each.

  • Do later:

    • Read 13.13 and 13.17 in text


Stabilizing selection
Stabilizing Selection

  • Selection that favors intermediate phenotypes

Stabilizing selection regulates birth weight


Directional selection
Directional Selection

  • Selection that favors extreme phenotypes in one direction

Peppered moths


Disruptive selection
Disruptive Selection

  • Selection that favors extreme phenotypes in both directions

Galapagos iguanas


Practice time
Practice time!

  • With a partner, come up with an example of stabilizing and directional selection.

  • Challenge: Can you think of an example of disruptive selection?


Popular misconceptions
Popular Misconceptions

  • Natural Selection does not createany traits.

    • It only selects on existing traits.

Where do new traits come from?


Popular misconceptions1
Popular Misconceptions

  • Natural Selection is not goal oriented

    • Simpler organisms are older, but not less fit.


Popular misconceptions2
Popular Misconceptions

  • Natural Selection is subject to constraints

    • Advantageous traits often come with trade-offs


4 20 12
4/20/12

  • Objective: To learn about hypotheses for the origin of cells

  • Do Now: In your notes, make a T chart to compare the conditions of early and modern Earth

  • Do Later: Read Ch. 15.1-3 in text



Evidence for early life
Evidence for Early Life

  • Stromatolites – 3.5 billion years old

    • Oldest fossils

    • Single celled organisms

    • Grow in mats that harden into rock


Cell theory
Cell Theory

  • Cell theory

    • All living things are composed of cells and their products

    • New cells arise from the division of older cells

    • Cells are the basic building blocks of life

    • Where did the first cells come from?


Miller s experiment
Miller’s Experiment

  • Stanley Miller (1953)

    • Hydrogen gas (H2)

    • Ammonia (NH3)

    • Methane (CH4)

    • Water vapor

    • Spark

  • Product? Amino acids.


Synthesis of nucleic acids
Synthesis of Nucleic Acids

  • Clay minerals catalyze the synthesis of DNA and RNA polymers

Montmorillonite


Meteorite delivery
Meteorite Delivery

  • Murchison meteorite (1969)

    • Found in Victoria, Australia

    • Over 100 amino acids

      • L-amino acids

    • Nitrogenous bases (DNA/RNA)

    • Potential for extraterrestrial life


Formation of protocells
Formation of Protocells

  • Lipids in water spontaneously arrange into vesicles

    • Hydrophobic effects

    • Can also be catalyzed by clay


Chicken egg problem
Chicken-Egg Problem

  • DNA is needed to make proteins, and proteins are needed to make DNA

    • Which came first?


Rna world
RNA World

  • 1989 – Discovery of catalytic RNA

    • RNA has a sequence of bases like DNA

    • RNA can catalyze reactions like proteins

Ribosomes contain RNA to help catalyze protein synthesis


Prokaryotic life
Prokaryotic Life

  • Oldest species on earth are prokaryotes

    • No membrane bound organelles


Eukaryotic life
Eukaryotic Life

  • Eukaryotic cells have membrane bound organelles


Mitochondria and chloroplasts
Mitochondria and Chloroplasts

  • Mitochondria and chloroplasts have unusual properties

    • Double phospholipid membrane

    • Mitochondrial/Chloroplast DNA


Endosymbiont theory
Endosymbiont Theory

  • Primitive prokaryotes became eukaryotic organelles


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