Evolution by wuyunyi

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									Evolution
 Sec. 16.1
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
GALAPAGOS ISLANDS
SPECIES VARIATION BETWEEN
ISLANDS
Mathus

• Discovered that the human population
 growth outpaces the food supply
   Darwin discovered species
     compete for survival
• Food
• Space
• Finding mates
• Escaping predators
• Shelter
SURVIVAL OF THE FITTEST

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

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

• BREEDING ORGANISMS WITH SPECIFIC
 TRAITS TO PRODUCE OFFSPRING WITH
 IDENTICAL TRAITS
DOG BREEDING: EX. OF
ARTIFICAIL SELECTION
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.
NATURAL SELECTION
Natural Selection:
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.
Structural Adaptations
• Changes in an
  organisms
  appearance or
  physical traits
                    MIMICRY
• Structural adaptation
    that allows one
    species to resemble
    another
•   Harmless species
    often adapt to look
    like harmful to protect
    themselves from
    predators
CAMOUFLAGE
     • STRUCTURAL
         ADAPTATION THAT
         ENABLES SPECIES TO
         BLEND WITH THEIR
         SURROUNDINGS
     •   Prevents species from
         being seem by
         predators.
PHYSIOLOGICAL ADAPTATIONS

• Changes in an organisms metabolic
  processes

• Ex: penicillin-resistant bacteria; pesticide
  resistant insects and weeds
      INDIRECT EVIDENCE OF
           EVOLUTION
• Fossils
• Anatomy
• Embryology
• Biochemistry
1. Fossils

• Provide record of early life
• Ex: Camels
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
Homologous Structures
   Ex: Forelimbs
2. Anatomy

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

• Compares DNA and RNA of different
 species to determine evolutionary
 relationships
MECHANISMS OF EVOLUTION
        SEC. 15.2
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
       CHANGES IN GENETIC
          EQUILIBRUIUM
• GENETIC DRIFT
• NATURAL SELECTION:
  – STABILIZING SELECTION
  – DIRECTIONAL SELECTION
  – DISRUTIVE SELECTION
            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
      STABILIZING SELECTION

• Favors average sized individuals

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

• Favors extreme variation
See #3
Elephants with
longer trunks are
able to reach
food/water more
easily.
         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.
      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.
        Geographic Isolation

• Physical barrier divides population
   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
REPRODUCTIVE ISOLATION
  GRADUALISM VS. PUNCTUATED
        EQQUILBRIUM
Gradualism               Punctuated
• Believes change will   • Change is rapid and
  happen slowly over       then long periods of
  many generations         equilibrium occur
                           between
    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
ADAPTAVIE RADIATION
DIVERGENT EVOLUTION
CONVERGENT EVOLUTION

								
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