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					           EVOLUTION
 Evolution - change over generations
 Organisms change over time – this
  is a fact. How organisms have
  changed throughout earth’s history
  is theory.
 EVIDENCE OF EVOLUTION

 Fossils
 Comparative anatomy
 Embryology
 Biochemistry
 Genetics
 Direct observation
                 FOSSILS
 Fossils - a trace of an organism that lived
  long ago
 Fossil records- use radiometric dating or
  rock layers to date fossils
 Fossil records are incomplete:
      • soft tissues
      • weather
 Geographic distribution of species
    Similar organisms in different areas

 Fossils of extinct organisms
  COMPARATIVE ANATOMY
 Comparative anatomy- The study of
  structures of different organisms
 Homologous structures - similar
  structures modified between
  different organisms
     • The more similar the structures,
       the closer the relationship
       between two organisms
     • Example: a bat’s wing, a horse’s
       leg and a human forearm
Homologous structures
 Vestigial Organs - structures that have no
  function in present organisms, but may
  have been used in ancestors
    Example in animals

      • pelvic bone in some snakes and whales
    Examples of vestigial organs in humans

      • appendix
      • wisdom teeth
      • body hair
      • pointed canines
A transitional fossil
          EMBRYOLOGY

 Comparative embryology - the
  study of embryos (early stages
  of life) of different organisms
  The more similar the embryos,
   the more closely related two
   organism are
 • ex. human and pig embryos appear
   very similar to each other
BIOCHEMISTRY & GENETICS

 Chemicals (like proteins, DNA,
  mRNA etc) in different
  organisms show similarities.
 More similar chemicals means
  more closely related
 Example- Hemoglobin in
  chimpanzees is very similar to
  hemoglobin in humans
             GENETICS
 How are offspring genetically
  different from their parents? In
  other words, how can evolution occur
  from one generation to the next?
    Meiosis – remember, individuals can

     make lots of genetically different
     sex cells
    Mutations – DNA can change!

    Sex – combines two individuals’

     DNA together
 DNA sequences of all living
  things have many similarities
 Base sequences of DNA
  • DNA of humans and
    chimpanzees is 98%
    identical
  • DNA of humans and other
    mammals is 80% identical
Hemoglobin sequences in vertebrates
   DIRECT OBSERVATION

 Direct observation - evolutionary
  changes are happening NOW
  • Example - bacteria becoming
    resistant to antibiotics
Charles Darwin in 1859, the year The
  Origin of Species was published
CHARLES DARWIN
 Charles Darwin – an
  Englishman credited for first
  describing natural selection
  • HMS Beagle – a British
    survey ship on which Darwin
    was a naturalist. This ship
    sailed around the world in
    1831.
Figure 15–1 Darwin’s Voyage
Section 15-1
 Galapagos Islands – located 600
  miles west of South America. The
  islands have very different
  climates and thus the organisms
  adapt according to the
  environment.
    Giant tortoise, marine iguanas,

     and finches vary from island to
     island due to different
     environments
     Giant Tortoises of the
       Galápagos Islands

                               Pinta
                                             Tower
                          Marchena
    Pinta Island
    Intermediate shell
                                  James
             Fernandina

                                          Santa Cruz

              Isabela
                                     Santa Fe

                                                       Hood Island
                              Floreana      Hood       Saddle-backed shell




Isabela Island
Dome-shaped shell
A Galápagos Islands tortoise
 Artificial Selection – people chose
  particular species to breed
  (selective breeding)
  Artificial selection helped to explain
   that variations in species could make
   them better adapted.
  Dog breeders, farmers, gardeners

   have been using artificial selection
   for years.
                   Cockapoo
   Golden
   Doodle

                                     Himilayan
                   Cocker spaniel
                   and poodle




Golden retriever
and poodle                          Persian and
                                    Siamese
Tangelo = madarin   Broccoliflower = broccoli
orange and          and cauliflower
grapefruit
Artificial selection: diverse vegetables
       derived from wild mustard
   NATURAL SELECTION:
  The survival of the fittest
 Darwin wondered why there were so
  many different species of finches on
  the Galapagos Islands. He proposed
  the concept of natural selection.
 Natural Selection - the best adapted
  individuals in a population survive and
  reproduce offspring that are also well
  adapted
 The least adapted produce fewer
  offspring and are less likely to
  survive.
 Among the various traits that exist,
  certain ones may benefit a population
 The environment typically does not
  cause the variation!
  • Examples
     • Virus from outer space – kills blue-
       eyed people (but does not change a
       person’s eyes to blue)
     • Spadefoot toad – must bury itself in
       the ground and mate quickly when it
       comes to the surface, therefore, it
       has a loud croak and long toes!
     TYPES OF SELECTION
 Directional Selection – when
  individuals at one end of the curve
  have higher fitness than individuals in
  the middle.
    Example: birds with larger beaks

     are better able to survive food
     shortages than those with small and
     medium beaks
Figure 16–6: Graph of
Directional Selection
                            Key
    Directional Selection         Low mortality,
                                  high fitness
                                  High mortality,
    Food becomes scarce.          low fitness
 Stabilizing Selection - when
  individuals at middle of the
  curve have higher fitness
  than individuals at the ends.
    Example – average-sized

     babies are most likely to
     survive compared to really
     big and really small babies
Figure 16–7: Graph of Stabilizing
           Selection
                 Stabilizing Selection

          Key
                Low mortality,
                high fitness
                High mortality,      Selection
                low fitness        against both
                                  extremes keep
                                   curve narrow
                                   and in same
                                      place.




         Birth Weight
 Disruptive selection - when
  individuals at both ends of the
  curve have higher fitness
  than individuals in the middle.
    Example: due to small and

     large seeds, birds with small
     and large beaks are most fit
     compared to birds with
     medium beaks
           Figure 16–8: Graph of
           Disruptive Selection

                                            Disruptive Selection

                                         Largest and smallest seeds become more common.
                    Number of Birds




                                                                            Number of Birds
Key
                     in Population




                                                                             in Population
  Low mortality,                                       Population splits
  high fitness                                         into two subgroups
  High mortality,                                      specializing in
  low fitness                                          different seeds.


                                      Beak Size                                               Beak Size
Disruptive selection in a finch population
Types of selection
         Some vocab…

 Gene Pool - the entire collection
  of genes among a population
 Population - All organisms within
  a breeding group (same species)
 Gene Frequency - The number of
  times an allele appears in a gene
  pool
Figure 16–2: Relative Frequencies
            of Alleles
   Sample                   Frequency of
  Population                   Alleles
                              allele for   allele for
         48%                  brown fur    black fur
     heterozygous
         black


                  16%
               homozygous
                  black
        36%
     homozygous
       brown
 Changes in gene frequency
  mean that the population has
  evolved.
 An entire population evolves,
  not an individual!
 A specific gene may be
  “selected” for by the
  environment.
          GENETIC DRIFT
 Genetic Drift - rapid changes in gene
  frequency of a small, isolated
  population
   Example: in small populations, a

    recessive allele can become much
    more common
   In the Amish population, certain

    genetic disorders are more common
    than in the general population.
             Genetic Drift
     Sample of
Original Population
                  Founding Population A
                                               Descendants




                       Founding Population B
               Genetic Drift
     Sample of
Original Population                           Descendants
                      Founding Population A




                      Founding Population B
            OCEANIC ANGLER FISH
                      Sexual dimorphism




     The deep sea angler shows a very strange sexual
dimorphism. The male is very small and attaches itself to the
 body of the female. The teeth and the jaw recedes and the
 blood circulating of the two animals become one. The male
      spends the rest of his life attached to the female.
       ADAPTATIONS
 Adaptations - physical traits
  of a living organism that help
  it to survive in its
  environment
 Adaptations evolve by
  chance!
    TYPES OF ADAPTATIONS
 Structural – physical parts
   • Ex. woodpecker’s tongue, anglerfish,
     anteater’s snout, hummingbird’s beak
 Physiological – chemicals made by
  organism
   • Ex. poison venom of a snake, ink of a
     squid
 Behavioral
    Ex. migration of birds, mating dances
Buffalo Bill Dam on the
Shoshoni River at Cody,
Wyoming and those dots
are bighorns WALKING
      ACROSS IT.
       TYPES OF EVOLUTION
 Convergent Evolution – when species that are
  not closely related evolve similar traits (two
  species look like they are closely related and
  they are not)
   • Example: dolphins (mammals) and sharks
     (fish)
 Divergent Evolution – one species evolves into
  two or more species with different
  characteristics
    Example: lions and tigers evolved from a

     common ancestor
Liger
                 Speciation
 Speciation –evolution of two different
  species from one common ancestor.
 What keeps two species apart so that they
  evolve differently?
 Isolating Mechanisms – keep groups apart
    Geographic Isolation – geologic changes

     occur that isolate individuals of a
     population
        – Ex. Squirrels separated by Grand
          Canyon and Darwin’s finches separated
          by being on different islands
Squirrels in the Grand Canyon
Figure 15–14: Geographic Distribution
          of Living Species

                                      Beaver

                NORTH                 Muskrat
               AMERICA
                            Muskrat   Beaver and
                                      Muskrat

                                      Coypu

                                      Capybara

                                      Coypu and
           Capybara         SOUTH
                                      Capybara
                           AMERICA




                         Coypu
   Genetic Isolation – genes don’t mix right
       – Donkeys and horses make mules, but
         mules are sterile.
   Temporal isolation – timings off
       – Different species of skunks that mate
         at different times of the year.
   Behavioral isolation – behaviors don’t
    match
       – Certain species of lightning bugs use
         different blinking patterns to attract
         mates.
A male bower bird
builds a “bower” to
attract mates.
 Blue footed boobies doing their
  mating dance
 Birds of Paradise doing their mating
  dance
 Many different mating scenarios
 THEORY OF ORIGIN OF
        LIFE
 Theory - a major hypothesis that
  has withstood the test of time
  • Based on observations and
    evidence
  • The closest to a complete
    explanation that science can
    offer
  • 40 second evolution
  • Homer Simpson Evolution
   ORIGINAL ATMOSPHERE

 Hydrogen cyanide, carbon dioxide,
  carbon monoxide, nitrogen,
  hydrogen sulfide, and water
 No oxygen gas
       FIRST ORGANISMS
 Prokaryotes [bacteria] - first cells;
  have genetic material (RNA or DNA);
  starting 3.5 bya
 First prokaryotes were heterotrophs
  (eat food)
 Later, some became autotrophs (make
  own food)
    Chemosynthesis - using energy from

     chemicals to make food
   Photosynthesis - using CO2 and light
    to make food
     • Cyanobacteria put oxygen into
       atmosphere.
     • Oxygen drove some life forms to
       extinction, while other life forms
       evolved new ways to use oxygen
       (aerobic respiration).
     • Oxygen formed ozone layer-
       shielded earth from harmful UV
       and allowed an explosion of life
       (2.7 bya)
 A painting of early Earth showing
volcanic activity and photosynthetic
    prokaryotes in dense mats
           Other big steps…
 Eukaryotes (cells with nuclei) about 2.2 bya
 Plants and animals begin in water
 Multicellular organisms and sexual
  reproduction in plants and animals (aquatic
  life)
    Increased genetic diversity

 Plants and later animals colonize land around
  4.5 mya.
 First dinosaurs and then first
  mammals (245 mya)
 Dinosaurs go extinct around 65 mya
  and this allows for evolution of larger
  mammals.
 Extinctions are often followed by
  explosions of new life forms!
 Remember your eras: Precambrium.
  Paleozoic, Mesozoic, and Cenozoic.
       HUMAN EVOLUTION
 Did man come from Monkey?
   NO!

 Humans and monkeys evolved from a
  common ancestor that lived
  approximately 65 million years ago and
  was a tree dweller (roughly the size of
  a cat). This was not a monkey like the
  monkeys today.
          Figure 32–16: Human and
              Gorilla Skeletons
                                Comparing Human and Gorilla Skeletons

Modern Human                      Modern Human        Modern Gorilla
               Modern Gorilla
                                 Skull atop           Skull atop
                                 S-shaped spine       C-shaped spine

                                 Spinal cord exits    Spinal cord exits
                                 at bottom of skull   near back of skull

                                 Arms shorter than    Arms longer than
                                 legs; hands do not   legs; hands touch
                                 touch ground         ground during
                                 during walking       walking

                                 Pelvis is bowl-      Pelvis is long
                                 shaped               and narrow

                                 Thigh bones angled   Thigh bones angled
                                 inward, directly     away from pelvis
                                 below body
      Evolution of Primates
 Anthropoids developed into 3
  groups:
   New World Monkeys – includes

    squirrel and spider monkeys; have
    prehensile tail (can coil around
    branches) and lived in trees;
    found in central and S. America
 Old World Monkeys –
  include giant apes, baboons,
  and macaques; do not have
  prehensile tail, but spend a
  lot of time in trees; found in
  Africa and Asia
 Hominoids (great apes) –

  include orangutans, gorillas,
  chimpanzees, and humans
              HOMINIDS
 Hominid family includes modern humans
  and several distinctly different extinct
  species
 Bipedal – two-foot locomotion
    Freed hands to use tools

 Opposable thumb – allowed hand to
  grasp objects and tools
 Increased brain size
 Family that walks on all four
Comparison of Skulls of Human
         Ancestors
                                  Large brow
                                     ridge




                                   Large nose
     Large canine
            teeth                  Face protrudes
                                   forward
               Australopithecus afarensis           Homo erectus

                                                                                Round, high
                    Weak brow                           Large                   skull
                      ridge                              brain
                                                         case
                       Inflated
                       cheeks

                       Large
                       nose                                                       Even teeth
                                                                                 Strong chin
         Neanderthal                   Cro-Magnon                  Modern Homo sapiens




 Human Evolution Shockwave video
Australopithecus afarensis
 Very small brain capacity
 ~3.9-3.0 million years ago (mya)
 “Lucy”
 Bipedal apes that spent some
  time in trees
 Short (Lucy is 1m)
         Homo habilis
 “Handy man”
 ~2.5 mya
 Increased brain size
 Began to make and use tools
 1.3 meters tall (4 feet tall)
         Homo erectus
 “Upright man”
 ~ 1.8 mya - 250,000 years ago
 Taller
 Larger brain capacity
  (comparable to modern humans)
 Built fires
 Migrated out of Africa into China
  and Asia
 Homo sapiens (“wise man”)
 Homo sapiens neanderthalis
   Neanderthals

   Overlapped in existence with

    modern humans
   Heavier brow ridge

   Slightly larger brain capacity

    than modern human
   Lived ~200,000 – 30,000 years

    ago
 Homo sapiens sapiens
     First arose in Africa around
      100,000 years ago.
     Lived with Neanderthals for
      ~50,000 years.
     Tools, art, and buried dead with
      rituals
     One group became Cro-Magnon (in
      Europe) ~40,000 years ago.
     We are Homo sapiens sapiens

				
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