EVOLUTION

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EVOLUTION Powered By Docstoc
					  Unit 3 Evolution
Reference Chapters: 15, 16, 17
         I. Vocabulary to Know
► Evolution:   A change in populations over a long
  period of time
► Variation: different genes=different characteristics
  (i.e. different colors of birds)
► Speciation: Changes in the relative frequencies of
  gene variations in a population that leads to the
  formation of new species
► Adaptation: process whereby a species becomes
  better suited to live in its habitat
► Fitness: ability of an organism to survive and
  reproduce in its specific environment
         I. Vocabulary to Know
► Genepool: genes of all members of a
 population
                                  An example of
                                  Evolution


    Glyptodon
(a CAR- sized mammal during the
Ice Age, found in South America
and related to today’s modern
armadillo)


                                        Armadillo
                                  (a cat sized mammal found in
                                  South America, Texas, Mexico &
                                  Florida)
               TIME LINE THEORIES
Greeks          Bonnet          Lamarck -         Darwin
theorize        observes        evolution         publishes On
organisms’      fossils don’t   occurs            the Origin of
form is         resemble        through:          Species;
related to      modern          A. the Use or     proposes
its function    organisms -     Disuse of         Natural
                must come       acquired traits   Selection
                from a          B. Desire to      and Fitness
                previous era    Change




 300 B.C.      1769 A.D.           1809               1859
           II. Lamark vs. Darwin
► A.Jean-Baptiste
  Lamarck
   His theory was that if a
    species used or didn’t use
    certain organs that would
    acquire (gain) or lose
    certain traits during their
    lifetime and those traits
    would be passed on to
    their offspring
   i.e. Giraffe needs long
    neck to eat, so it grows a
    longer neck
  II. Lamark vs. Darwin

► B.   Charles Darwin
   Traveled around the
    world for 5 years on
    the HMS Beagle from
    1831-1836
   Noted characteristics
    of hundreds of animals
    and plants
   Stopped at the
    Galapagos Islands
                  Charles Darwin
► Whileon the Galapagos
 Islands, Darwin observed:
   Each island had a different
    climate
   Each island was inhabited
    by finches (type of bird)
   Each island also had other
    species of birds that had
    similar characteristics as
    the finches on that island
   Differences between
    Finches found on different
    islands
                         Finches
►   What differences do you see?
►   What hypotheses can be made by the differences between
    finches, and the observations Darwin made while at the
    Galapagos Islands?
              Charles Darwin
► Based  on the different adaptations and similar
  characteristics of the finches from the different
  Galapagos islands he was curious if the finches
  were once members of the same species (came
  from a common ancestor)
► Remember speciation? Why would this be a good
  example of speciation?
    As a finch adapted to its environment, species
     diversity also increased
Finches
                   Hypothesize…
► What  might
 have occurred
 that changed         ----- Original
                            Population
                                         New
                                         Population
 the size of
 beaks from the
 original to the
 new
 population?
                 Hypothesize…
► What   might         ----- Original     New
 have                        Population   Population

 occurred
 that changed
 the size of
 beaks from
 the original
 to the new
 population?
                 Hypothesize…
► What   might         ----- Original     New
 have                        Population   Population

 occurred
 that
 changed
 the size of
 beaks from
 the original
 to the new
 population?
      Charles Darwin
► 1859   - Darwin published On
  the Origin of Species
► Proposed   how evolution works
  through Natural Selection
► Natural Selection - a process
  by which individuals who are
  best fit (adapted) to live in
  their environment survive and
  reproduce successfully
  (survival of the fittest)
      III. Theory of Evolution
►A   scientific explanation for the unity and
  diversity of life
► Evolution cannot act at the individual level,
  but instead in a species’ population over time
► Variation of populations allow for evolution
  to occur and therefore new species emerge
  (come about) as well
► If all cells come from pre-existing cells… then
  all species come from pre-existing species
► Recall what a SCIENTIFIC THEORY is…
     A. Evidence
     Supporting
      Evolution
(Change over time)
1. Fossil Record
        Compare/Contrast
         organisms and
         how they changed
         over time




Fossilized remains of Fairies. This is a joke!
        Lets use that fossil record…
►   Which of the following
    fossils (W, X or Y) is the
    youngest? Why?

►   Which layer of earth is the
    oldest? Why?

►   Based on these layers of
    earth, what might a
    paleontologist (scientist
    who studies fossils) use to
    determine what caused a
    mass extinction?
       Reading Sedimentary Rock
Where is the oldest layer?


Where is the youngest
layer?

Where are the most simple
organisms?


Where are the most
complex organisms?
      A. Evidence Supporting Evolution
                  (Common Ancestry)
1. Biogeography
     distribution of
      biodiversity over
      space and time
     Similar organisms
      are found all over
      the world
     Supported by
      Continental Drift
      Theory
      A. Evidence Supporting Evolution
                      (Common Ancestry)
2. Homologies
(Similar characteristics of different species)
     Anatomical Structures
       ► Structures evolved from a
           structure of a common ancestor
       ► Ex: arms of humans similar to
           insectivores
     A. Evidence Supporting Evolution
                (Common Ancestry)
2. Homologies
      A. Evidence Supporting Evolution
                      (Common Ancestry)
2. Homologies
(Similar characteristics of different species)
     Anatomical Structures
        (Homologous structures)
      A. Evidence Supporting Evolution
                      (Common Ancestry)
3. Homologies
(Similar characteristics of different species)
     Molecular
       ► Organisms share similar
           molecular make-up
       ► e.g. DNA
     A. Evidence Supporting Evolution
                   (Common Ancestry)
3. Homologies
     Developmental (Embryonic)
      ► Organisms are similar
         during development
      ► Common cells and tissues
         (embryonic cells) growing
         in similar ways produce
         the homologous
         structures.
A. Evidence Supporting Evolution
           (Common Ancestry)
3. Vestigial Organs
   a body structure in a present-day
    organism that no longer serves its original
    purpose, but was probably useful to an
    ancestor
   Ex. Pelvic bones in baleen whales,
    appendix in humans, limbs in snakes
    A. Evidence Supporting Evolution
                (Common Ancestry)
3. Vestigial Organs
     Top 10 signs of Evolution in Modern Man
                 http://listverse.com/2009/01/05/top-10-signs-of-evolution-in-modern-man/




1.    Goose Bumps
2.    Jacobson’s Organ
3.    Junk DNA
4.    Extra Ear Muscles
5.    Plantaris Muscle
6.    Wisdom Teeth
7.    Third Eyelid
8.    Darwin’s Point
9.    Coccyx
10.   Appendix
               B. Natural Selection
► “Survival   of the Fittest” is only part of NS
   Not only must the organism survive, it must also attract a
    mate and successfully reproduce
► Fitness
   Linked to reproductive success
   The more offspring an organism has that reach maturity, the
    more fit it is
   NOT necessarily the strongest or fastest; not linked to
    physical strength
► ThisNatural Selection produces changes within a
  population… but how?
   Cricket Discussion Questions
When it comes to crickets, what does fitness
    mean?
Is calling good or bad for a cricket's fitness?
Give some examples of selection at work in
    this cricket story.
How does selection favor calling? How does
    selection favor not calling?
 B. Natural Selection-application
► Throughout  the history of the earth, a lot of
 catastrophic events have happened (i.e.
 theory of the meteor hitting earth during
 the dinosaurs, hurricanes, etc.). Why does
 life continue?
    I. Elements of Natural Selection
►   Variation
     Allows a population to become better suited for their environment
      over time (AKA: evolution)
     Ex. Giraffe
►   Inherited variation
     Can be physical or behavioral
     Which of the following is and is not genetically passed on?
        ► Eye  color
        ► Big muscles
        ► Hair/fur color
        ► General size (ht/wt)
        ► Sense of humor
        ► Left or Right handedness
 I. Elements of Natural Selection
► Remember     carrying capacity?
   What happens when a population produces more
    offspring than the carrying capacity of their
    habitat?
   Which offspring will live and which will die?


► The   result is differential reproductive success
   The best adapted organisms will successfully
    reproduce, therefore pass on their genes
  I. Elements of Natural Selection
► Adaptation
► How   is adaptation related to Natural Selection?
   Adaptation is driven by NS because the
    adaptations that help an organism survive and
    reproduce will be passed onto further generations
  II. Natural Selection Wrap-up
► How   does NS affect diversity?
   ANSWER: It increases diversity because
    organisms that are best suited for their
    environment have greater fitness.


► How   does NS affect (natural) extinctions?
   ANSWER: If a population is not able to adapt to
    its environment, it will eventually become
    extinct
 III. Other Evolutionary Mechanisms
► Genetic  Drift – change in the frequency of a gene
  variant in a population
   Scientists consider Genetic drift to be a random change in
    a population
     ► When  would the frequency of a gene variation increase?
     ► ANSWER: When the variation is favored, or improves the
       population’s fitness
► Gene  Flow – transfer of genes from one population
  to another
   Immigration brings new genes or gene variations to a
    population’s gene pool
   Emigration removes gene variants from a population’s
    gene pool
 III. Other Evolutionary Mechanisms
► Mutation  – random change to a sequence of DNA;
  the fuel for NS
   Creates a new variation, and if that variation increases
    the fitness of that organism, the adaptation is passed on,
    changing the characteristics of the population over time
► These  mechanisms cause a new trait to arise in a
  single organism, therefore a new variation
   Hypothesize what would happen to that organism if the
    new variation improves its fitness?
   What would happen if it decreases its fitness?
 III. Other Evolutionary Mechanisms
► Genetic   Equilibrium
   Gene frequency in a population remains constant and
    therefore the population will not evolve.
     ► 5 Conditions required:
          There must be random mating
          The population must be very large
          There can be no movement into or out of the
           population
          No mutations
          No Natural Selection
   Hypothesize what would happen to an organism in
    genetic equilibrium?
   Which of the 5 conditions would be easiest to change for
    an animal that lives in the Savannah of Africa?
                       Let’s Discuss
► Whatfactors do you think
 might influence speciation?
   Environmental Pressures?
   Physical separation
    (isolation)?
     ► Example?
     ► Galapagos   Finches
IV. How about the Environment?
► The environment places selective pressure on
  organisms
    Ex. Giraffe and tall trees
    Ex. Plants retain more water due to extended periods of
     drought
► Due   to these selective pressures, the frequency of
  traits that make an organism better adapted will
  increase in future generations
► Decreases diversity in a population because the
  unsuccessful variants are eliminated
               Reminders
► Quizover Evolution vocabulary and notes
  tomorrow!
► Exam next Thursday (10/21) over Evolution!
        V. Mechanisms of Speciation
   1. Behavioral Isolation
     When two species are capable of interbreeding, but
      have differences in courtship rituals or other behavioral
      strategies
     i.e. eastern and western meadowlark live in similar
      areas but have different mating songs
   2. Geographic Isolation
     Separation of populations by barriers (i.e. rivers,
      mountains, bodies of water)
 3. Temporal Isolation
       Organisms reproduce at different times of the year
    V. Mechanisms of Speciation
   1. Behavioral Isolation - Examples
            VI. Human Intrusion
► Artificial    Selection – nature provided the
  variation, and humans selected those variations that
  they find useful or most beneficial
► i.e. selecting only the best chickens to mate

Welsh Terrier         Otterhound          Airedale Terrier




                +                   =
        Artificial Selection
                               Liger




Tiger   +   Lion   =
          C. Patterns of Evolution
► 1. Five   types
    A. Extinction due to Natural Selection
      ►Can happen with only 1 food source, live in
        rare habitat or reproduce slowly.

    B. Mass extinctions
      ► allow for surviving species (DIVERSITY!) to
       rapidly evolve because now new habitats are
       available
    C. Adaptive radiation
      ►A single species has evolved into several
        different forms that live in different ways
       C. Adaptive Radiation




  The polar bear diverged
from the black bear due to
   geographic isolation
         D. Convergent Evolution
► Unrelated organisms
 begin to resemble one
 another over time
► How?
 Common Environment

 Same Adaptations
              E. Coevolution
► Twospecies influence each other’s
 evolution due to a symbiotic relationship
   What will happen if…
 Example: Humming
 birds and plants with
   long-tube flowers
         Build a Beast Activity
► Get out a piece of paper.
► You will have 1 minute to find a partner.
  Write both names on your paper in the top
  right corner.
► You will have 10 minutes to read the
  directions and roll your dice to determine
  the adaptations your beast must have to
  survive. Write the answers to A-E on your
  sheet of paper.
► For the rest of class, you will need to draw
  your beast on the legal size sheet of paper
  provided.
          Build a Beast Activity
► After  our quiz tomorrow, you will work with
  your partner again to write a paragraph
  describing the beast you have built, and
  color your picture.
► This activity will be turned in for a grade.
► All directions MUST be followed.
     A. Evidence
     Supporting
      Evolution
(Change over time)
1. Fossil Record
        Compare/Contrast
         organisms and
         how they changed
         over time




Fossilized remains of Fairies. This is a joke!
        Lets use that fossil record…
►   Which of the following
    fossils (W, X or Y) is the
    youngest? Why?

►   Which layer of earth is the
    oldest? Why?

►   Based on these layers of
    earth, what might a
    paleontologist (scientist
    who studies fossils) use to
    determine what caused a
    mass extinction?
       Reading Sedimentary Rock
Where is the oldest layer?


Where is the youngest
layer?

Where are the most simple
organisms?


Where are the most
complex organisms?
 III. Other Evolutionary Mechanisms
► Mutation  – random change to a sequence of DNA;
  the fuel for NS
   Creates a new variation, and if that variation increases
    the fitness of that organism, the adaptation is passed on,
    changing the characteristics of the population over time
► These  mechanisms cause a new trait to arise in a
  single organism, therefore a new variation
   Hypothesize what would happen to that organism if the
    new variation improves its fitness?
   What would happen if it decreases its fitness?
        The Hands of a Primate




Pick up your pencil between your thumb and your index finger
              Tasks – Choose 8
► Remove one shoe
► Put your shoe on again and tie the laces
► Put on a jacket or sweater
► Unbutton a button and button it again
► Unscrew a bottle cap
► Write your name and address
► Comb your hair
► Take off your wristwatch and put it back on again
► Unzip & Zip your backpack
► Open and close a zip-loc baggie
► Take out an earring and put back in
► Get a piece of tape from the tape dispenser
           Review Questions
► How   do species evolve?
► How do organisms and the environment
  affect each other?
► How is evolution studied?
► How does evolution explain similarities and
  differences in living things?

				
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