Evolution

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Evolution

• Sec. 16.1

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Darwin and Natural Selection

• Evolution Change in a population over time
• Galapagos Islands
• -located off the west coast of South America
• -Darwin studied species of animals and plants
  and found that species varied between islands

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GALAPAGOS ISLANDS
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SPECIES VARIATION BETWEEN ISLANDS
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Mathus

• Discovered that the human population growth
  outpaces the food supply

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Darwin discovered species compete for survival

• Food
• Space
• Finding mates
• Escaping predators
• Shelter

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SURVIVAL OF THE FITTEST

• ONLY THE BEST FIT FOR THE ENVIRONMENT SURVIVE TO
  REPRODUCE!

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DARWINS DISCOVERIES

• EACH GENERATION OF NEW SPECIES SHOWS VARIATION IN
  TRAITS THROUGH
• 1. ARTIFICIAL SELECTION
• 2. NATURAL SELECTION

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ARTIFICIAL SELECTION

• BREEDING ORGANISMS WITH SPECIFIC TRAITS TO
  PRODUCE OFFSPRING WITH IDENTICAL TRAITS

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DOG BREEDING EX. OF ARTIFICAIL SELECTION
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NATURAL SELECTION

• PROCESS OF SELECTION WHICH OCCURS IN NATURE
• ORGANISMS WITH CERTAIN VARIATIONS SURVIVE,
  REPRODUCE AND PASS VARIATIONS TO NEXT GENERATION
• ORGANISMS WITHOUT THESE VARIATIONS ARE LESS
  LIEKLY TO SURVIVE AND REPRODUCE.

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NATURAL SELECTION
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Natural Selection
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ADAPTATIONS

• VARIATIONS THAT AID ORGANISMS IN SURVIVAL IN
  THEIR ENVIRONMENT
• Ex thorns on plants, distinct coloration of
  animals
• Darwin believed adaptations occurred over many
  generations.

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Structural Adaptations

• Changes in an organisms appearance or physical
  traits

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MIMICRY

• Structural adaptation that allows one species to
  resemble another
• Harmless species often adapt to look like harmful
  to protect themselves from predators

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CAMOUFLAGE

• STRUCTURAL ADAPTATION THAT ENABLES SPECIES TO
  BLEND WITH THEIR SURROUNDINGS
• Prevents species from being seem by predators.

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PHYSIOLOGICAL ADAPTATIONS

• Changes in an organisms metabolic processes
• Ex penicillin-resistant bacteria pesticide
  resistant insects and weeds

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INDIRECT EVIDENCE OF EVOLUTION

• Fossils
• Anatomy
• Embryology
• Biochemistry

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1. Fossils

• Provide record of early life
• Ex Camels

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2. Anatomy

• Homologous structures structures with common
  evolutionary origin
• - can be similar in structure, function, or
  both
• - believed structures are evidence of
  evolution from an common ancestor

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Homologous StructuresEx Forelimbs
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2. Anatomy

• Analogous Structures features that do not have
  a common evolutionary origin but are similar in
  function.
• Ex Butterfly wing and Bird wing

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Analogous Structures
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2. Anatomy

• Vestigial Structures structures that have no
  function now but did in an ancestor
• A structure becomes vestigial when it is no
  longer needed.

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Vestigial Structure
Appendix is no longer used in humans so it is
considered a vestigial structure. (need when we
ate more of a plant based diet)
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3. Embryology

• Easy to distinguish adult bird and mammal but
  difficult to distinguish embryos.
• Embryo earliest stage of growth and development
  of an organism
• Suggest evolution of common ancestors

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Embryology
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4. Biochemistry

• Compares DNA and RNA of different species to
  determine evolutionary relationships

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MECHANISMS OF EVOLUTION

• SEC. 15.2

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POPULATION GENETICS

• GENE POOL ALL THE ALLELES OF A POPULAITONS
  GENES
• ALLELE FREQUENCY PERCENTAGE OF A SPECIFIC ALLELE
  IN A POPULATION
• GENETIC EQUILIBRIUM WHEN THE ALLELE FREQUENCY
  REMAINS THE SAME OVER GENERATIONS

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CHANGES IN GENETIC EQUILIBRUIUM

• GENETIC DRIFT
• NATURAL SELECTION
• STABILIZING SELECTION
• DIRECTIONAL SELECTION
• DISRUTIVE SELECTION

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GENETIC DRIFT

• ALTERATION OF ALLELIC FEQUENCIES BY CHANCE
  EVENTS COMMONLY OCCURS IN SMALL POPULATIONS
• Ex Amish Settlement in PA
• 1 in 14 (short arms, legs, extra fingers and
  toes)
• 1 in 1000 in US population in general

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STABILIZING SELECTION

• Favors average sized individuals

Small cannot compete for food large are seen by
predators. SEE 1
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DIRECTIONAL SELECTION

• Favors extreme variation

See 3 Elephants with longer trunks are able to
reach food/water more easily.
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DISRUPTIVE SELECTION

• Favors either extreme

See 2 Marine Limpets with white, tan and dark
brown shells. The white and brown are camouflaged
as rocks while tan are easily seen.
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EVOLUTION OF SPECIES(SPECIATION)

• SPECIES Groups of organisms that look alike and
  can interbreed to produce fertile offspring
• SPECIATION The evolution of a new species
• Occurs when members of a population can no longer
  interbreed and produce fertile offspring.

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Geographic Isolation

• Physical barrier divides population

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REPRODUCTIVE ISOLAION

• GENETIC MATERIAL BECOMES TO DIFFERENT TO MATE.
• BEHAVIOR MAY MATE AT DIFFERENT TIMES OF YEAR
• POLYPLOIDY INDIVIDUALS WITH AN EXTRA SET OF
  CHROMOSOMES CANNOT MATE SUCCESSFULLY

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REPRODUCTIVE ISOLATION
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GRADUALISM VS. PUNCTUATED EQQUILBRIUM

• Gradualism
• Believes change will happen slowly over many
  generations

• Punctuated
• Change is rapid and then long periods of
  equilibrium occur between

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PATTERNS OF EVOLUTION

• Adaptive radiation
• Ancestors evolve into an array of species to fit
  the environment
• Divergent evolution
• Species becomes increasingly distinct from
  original ancestor
• Convergent evolution
• Unrelated species that occupy similar
  environments in different parts of the world
  undergo similar natural selection

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ADAPTAVIE RADIATION
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DIVERGENT EVOLUTION
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CONVERGENT EVOLUTION