EVOLUTION

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EVOLUTION

• ITS ALL ABOUT
• CHANGE!!!

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EVOLUTION

• CHANGES IN
• POPULATIONS
• SPECIES
• GROUPS OF SPECIES
• CHANGES OVER TIME

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MODERN DAY IDEAS ABOUT EVOLUTION

• POPULATIONS OF ORGANISMS CAN CHANGE
• CHANGES ARE DUE TO CHANGES IN ALLELE FREQUENCIES
  FROM ONE GENERATION TO ANOTHER
• SOME TRAITS INCREASE IN FREQUENCY, SOME DECREASE
  IN FREQUENCY
• ADAPTIVE TRAITS INCREASE WHILE
• MALADAPTIVE TRAITS DECREASE OR POSSIBLY
  DISAPPEAR

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MODERN DAY EVOLUTION

• SUBDIVIDES THE STUDY INTO 2 BROAD AREAS
• MICROEVOLUTION DESCRIBES HOW POPULATIONS CHANGE
  FROM GENERATION TO GENERATION AND HOW NEW SPECIES
  ORIGINATE
• MACROEVOLUTION DESCRIBES PATTERNS OF CHANGE IN
  GROUPS OF RELATED SPECIES OVER TIME AND SHOWS
  EVOLUTIONARY RELATIONSHIPS OF SPECIES

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OPPOSING VIEWS ON ORIGIN OF LIFE

• CREATIONISM
• BIBLICAL ACCOUNT RECORDED IN GENESIS CHAPTER 1
• EVOLUTION
• SCIENTIFIC EXPLANATION

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CHARLES DARWIN

• FATHER OF EVOLUTION
• REARED IN CHRISTIAN FAMILY
• STUDIES THEOLOGY AND MEDICINE
• DISLIKED SCHOOL
• APPOINTED A NATURLIST ON HMS BEAGLE
• COMPLETED EXTENSIVE MAPPING, RECORDING, COLLECTING

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CHARLES DARWIN

• DID EXTENSIVE STUDY IN SOUTH AMERICA AND
  GALAPAGOS ISLANDS
• VERY INTERESTED IN FLORA AND FAUNA
• INFLUENCED BY WORKS HE READ ON BOARD SHIP
• PUBLISHED ORIGIN OF SPECIES BY NATURAL SELECTION,
  1859

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INFLUENCES ON DARWIN

• CUVIER
• FOSSIL RECORD, GLOBAL CATASTROPHES, REPOPULATION
• HUTTON AND LYELL
• AGE OF EARTH, PROPOSED A TIME FRAME FOR EVOLUTION
• MALTHUS
• STRUGGLE FOR EXISTENCE LED TO SURVIVAL OF FITTEST
• ERASMUS DARWIN
• ORGANISMS CHANGE IN RESPONSE TO ENVIRONMENT,
  CHANGES PASSED ON

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LAMARCKS THEORY, 1809

• FIRST WELL ORGANIZED THEORY OF EVOLUTION
• USE AND DISUSE
• INHERITANCE OF ACQUIRED CHARACTERISTICS
• ENVIRONMENT IS A FACTOR IN CHANGE - IMP. TO DARWIN

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DARWINS THEORY

• NATURAL SELECTION
• RESULTS FROM INTERACTION BETWEEN GENES AND
  ENVIRONMENT
• WEEDING OUT PROCESS, DOES NOT PRODUCE NEW TRAITS
  BUT ACTS UPON TRAITS THAT ALREADY EXIST
• SURVIVAL OF THE FITTEST
• INDIVIDUALS WITH BEST ADAPTIVE TRAITS SURVIVE
• THOSE WHO SURVIVE PASS ON THEIR ADAPTIVE TRAITS
  TO OFFSRPING

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DARWINS THEORY

• 8 POINTS COVERED ON HAND-OUT

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TYPES OF NATURAL SELECTION

• BASED ON LONG PERIOD OF TIME
• BASED ON INTERACTION OF GENES AND ENVIRONMENT
• BASED ON PREMISE THAT EACH ALLELES FREQUENCY MAY
• INCREASE
• DECREASE
• DISAPPEAR
• NATURAL SELECTION HAND-OUT ACTIVITY

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STABILIZING SELECTION

• MOST COMMON (AVERAGE) INDIVIDUALS HAVE SELECTIVE
  ADVANTAGE
• EXTREMES ARE SELECTED AGAINST

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DIRECTIONAL SELECTION

• ONE EXTREME HAS SELECTIVE ADVANTAGE
• AVERAGE AND OTHER EXTREME ARE SELECTED AGAINST

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DISRUPTIVE SELECTION

• ALSO CALLED DIVERSIFYING SELECTION
• BOTH EXTREMES HAVE SELECTIVE ADVANTAGE
• AVERAGE IS SELECTED AGAINST

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SEXUAL SELECTION

• DIFFERENTIAL MATING OF INDIVIDUALS
• USUALLY RELATES TO MALES BUT CAN RELATE TO
  FEMALES
• MALE COMPETITION FOR MATE
• FEMALE CHOICE OF MATE
• COMMON IN BIRDS AND MAMMALS

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MEASURING MICROEVOLUTION

• HARDY-WEINBERG EQUILIBRIUM
• ALLELE FREQUENCIES REMAIN CONSTANT FROM
  GENERATION TO GENERATION
• AT H-W EQUILIBRIUM, NO EVOLUTION IS OCCURRING
  THERE IS ZERO EVOLUTION

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H-W CONDITIONS

• IF THERE IS ZERO EVOLUTION, THE FOLLOWING
  CONDITIONS ARE BEING MET
• NO NATURAL SELECTION IS IN EFFECT
• NO MUTATIONS OCCUR
• NO GENE FLOW OCCURS POPULATION IS ISOLATED
• NO GENETIC DRIFT OCCURS POPULATION IS LARGE
• MATING IS RANDOM

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REMEMBER

• POPULATIONS EVOLVE, NOT INDIVIDUALS
• POPULATION NATURAL INBREEDING GROUP OF
  ORGANISMS IN A GIVEN PLACE AT A GIVEN TIME
• NATURAL POPULATIONS ARE FOREVER CHANGING DUE TO
  VARIATION FACTORS
• H-W CAN BE USED TO MEASURE CHANGES

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H-W EQUATIONS

• p q 1
• p all dominant alleles
• q all recessive alleles
• 1 whole population or 100
• Results in phenotype frequencies of a population
• Example In a population of mice, 80 have long
  tails, 20 have short tails.
• p .8 q .2 so p q 1 or 100

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H-W EQUATIONS

• p2 2pq q2 1
• p2 homo dominant genotypes
• 2pq hetero dominant genotypes
• q2 homo recessive genotypes
• 1 whole population or 100
• Example In the mice population listed before,
  where p .8 q .2
• .82 2 ( .8 x .2) .22 1
• .64 .32 .04 1
• 64 homo dom 32 hetero dom 4 homo rec

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H-W EQUATIONS

• PROBLEMS TO WORK
• LAB ACTIVITY

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PURPOSE OF H-W

• PREDICT OUTCOMES OF RANDOM MATING
• DETECT CHANGE IN POPULATIONS
• DETERMINE MAGNITUDE OF CHANGE
• DETERMINE DIRECTION OF CHANGE
• UNCOVER FORCES OF CHANGE

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MACROEVOLUTION

• DESCRIBES PATTERNS OF CHANGES IN RELATED SPECIES
  OVER LONG PERIODS OF GEOLOGIC TIME
• DETERMINE PHYLOGENY EVOLUTIONARY RELATIONSHIPS
  AMONG SPECIES AND GROUPS OF SPECIES

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MACROEVOLUTIONARY PATTERNS

• GRADUALISM EVOLUTION OCCURS BY GRADUAL
  ACCUMULATION OF SMALL CHANGES
• PUNCTUATED EQUILIBRIUM LONG PERIODS OF NO
  EVOLUTION INTERRUPTED BY SHORT SPURTS OF RAPID
  EVOLUTION

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MACROEVOLUTION

• RESULTS IN SPECIATION FORMATION OF NEW SPECIES
• SPECIES DEFINED GROUP OF INDIVIDUALS THAT CAN
  INTERBREED AND PRODUCE FERTILE OFFSPRING

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PROCESSES OF SPECIATION

• ALLOPATRIC SPECIATION RESULTS IN ISOLATION OF
  ORGANISMS BY GEOGRAPHICAL BARRIERS THAT PREVENT
  INTERBREEDING
• SYMPATRIC SPECIATION FORMATION OF NEW SPECIES
  WITHOUT GEOGRAPHIC ISOLATION, SUCH AS HYBRIDS

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MAINTAINING REPRODUCTIVE ISOLATION

• MAINTAINS SPECIES WHEN ORGANISMS ARE NOT
  SEPARATED BY GEOGRAPHICAL BARRIERS
• TWO METHODS
• PREZYGOTIC ISOLATION
• POSTZYGOTIC ISOLATION

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PREZYGOTIC ISOLATION

• HABITAT ISOLATION
• SEASONAL ISOLATION
• BEHAVIORAL ISOLATION
• MECHANICAL ISOLATION
• GAMETIC ISOLATION

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POSTZYGOTIC ISOLATION

• HYBRID INVIABILITY
• HYBRID STERILITY

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PATTERNS OF SPECIES EVOLUTION

• DIVERGENT SHARE A COMMON ANCESTOR BUT BECOME
  LESS SIMILAR OVER TIME
• CONVERGENT SHARE SIMILAR ECOLOGICAL CONDITIONS
  OR LIFESTYLES BECOME MORE SIMILAR OVER TIME
• PARALLEL SHARE COMMON ANCESTOR BUT HAVE SIMILAR
  EVOLATIONARY CHANGES
• CO-EVOLUTION EVOLVE IN RESPONSE TO ANOTHER
  SPECIES

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GEOLOGICAL TIME LINES

• OUTLINE STEPS IN EVOLUTION
• SHOW ADAPTIVE RADIATION RAPID EVOLUTION OF MANY
  SPECIES FROM A SINGLE ANCESTOR
• SHOW MASS EXTINCTIONS OF SPECIES PROBABLY
  CREDITED TO SUDDEN ENVIRONMENTAL CHANGES

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EVIDENCE TO SUPPORT EVOLUTION

• PALEONTOLOGY
• BIOGEOGRAPHY
• EMBRYOLOGY
• COMPARATIVE ANATOMY
• HOMOLOGOUS STRUCTURES
• ANALOGOUS STRUCTURES
• VESTIGIAL ORGANS
• MOLECULAR BIOLOGY