Transcript Evolution - Fulton County Schools

Evolution
Chapter 16.1, 16.2, and 16.3
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Overall Theme of
Evolution
 Evolution Requires 3 elements:
 1. Variety
 2. Selection
 3. Time
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Variety
 For evolution to occur, there must be
ways for organisms within a species to
be different from each other
 Variety is generated through mutations
and sexual reproduction
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Evolution is now
considered a Theory
 What is the difference between a Theory
and a Hypothesis?
 Theory- a hypothesis that has been
confirmed by testing and has much evidence
backing it up
 Hypothesis- an educated guess that can be
tested
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Charles Darwin
 Charles Darwin took many
years to publish his theory of
evolution by natural
selection.
 Many of his ideas were first
inspired by his 1831 global
voyage on the ship called
the Beagle.
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Charles Darwin
(1809 – 1882)
 In l831, when Darwin was only 22 he
signed on as the ship’s naturalist aboard
the Beagle on a 5-year expedition around
the world.
 Darwin studied and collected many
different and unusual specimens which
contributed to his theory.
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Darwin’s Voyage to the
Galapagos Islands
 Some of Darwin’s most important
observations were made on the
Galapagos Islands.
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Animals of the
Galapagos Islands
Blue Footed Boobies in the Galapagos
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Galapagos Islands:
Finches
 Darwin observed
organisms with
slight differences.
 Example: Galápagos
finches with
different beaks
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Assumptions At That Time
 Species were fixed creations that
never changed and they were
arranged from least complex to most
complex.
 Earth is only a few thousand years
old.
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Darwin’s Book:
On the Origin of Species
 Darwin’s book stated:
1) Species change
2) Species evolved from a common
ancestor over time (implying a much
older Earth)
3) Natural Selection is the mechanism for
change
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The only picture in
Darwin’s book shows
Common Ancestry
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Who influenced
Darwin’s Ideas?
1. Jean Baptiste Lamarck (Biology)
2. Thomas Malthus (Economics)
3. Charles Lyell (Geology)
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Jean Baptiste Lamarck
 Lamarck proposed that organisms
change over time as they adapt to
changing environments.
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Jean Baptiste Lamarck
 He also incorrectly proposed that
changes due to use and disuse of a
characteristic would be passed on to
offspring.
 Example: A baseball player’s children would
inherit strong arm muscles
 Giraffe’s neck stretches
to reach food
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Charles Lyell
 Lyell studied fossils and rock layers
 His work showed that Earth’s history
was long enough for species to have
evolved gradually.
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Charles Lyell
 Lyell found evidence of long extinct
habitats
 Example: Fossil sea shells in the Andes
Mountains
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Thomas Malthus
 Malthus observed that human
populations were increasing faster than
the food supply.
 Darwin saw that all kinds of organisms
tend to produce more offspring than can
survive.
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Darwin’s Theory of
Natural Selection
1)
Overproduction- Organisms produce more
offspring than can survive. Leads to competition
for resources.
2)
Variety- Variation exists within every population.
3)
Selection- Having a particular trait can make
individuals more or less likely to survive and
reproduce offspring
4) Adaptation– Over time, the traits that improve
survival and reproduction become more
common.
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Artificial Selection
 A human practice of breeding
animals or plants that have
desired traits
 Example: Pigeon and Dog
breeders
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Artificial Selection
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Evidence for
Evolutionary Theory
1.
2.
3.
4.
5.
6.
Galapagos Finches
Transitional Fossils
Biogeography
Embryology
Homologous Structures
Biochemistry
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Galapagos Finches
 All Galapagos finch species are similar to
each other.
 Beak size and shape are different due to
different types of food.
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Transitional Fossils
 Traces of organisms that lived in the
past.
 Some fossils show a pattern of gradual
change from the past to the present
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Transitional Fossils
Tiktaalik roseae (Amphibian/Fish)
Fossils dated 375 million years old
Transitional Fossils
Archaeopteryx lithographica (Bird/Reptile)
Fossils dated 150 million years old
Transitional Fossils
Ambulocetus natans
Fossils dated ~ 50 million years old
Transitional Fossils
Rodhocetus kasrani
Fossils dated ~ 46 million years old
Transitional Fossils
Basillosaurus cetoides
Fossils dated ~ 40 million years old
Transitional Fossils
Physeter macrocephalus
Modern sperm whale
Fossils: Common Ancestry
 Darwin found fossils of
Giant extinct Armadillos
in South America that are
related to Modern day
Armadillos.
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Biogeography
 Study of the locations of organisms
around the world.
 Example: The Rhea, Ostrich, and Emu are
similar in size, shape, eating habits, and
habitat. However each species lives on a
separate continent. (Convergent Evolution)
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Biogeography
 Rhea (South America)
 Ostrich (Africa)
 Emu (Australia)
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Embryology
 Study of the first stage of development
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Homologous Structures
 Characteristics that are similar in
structure but different in function
 Homo = Same
 Same evolutionary history
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Homologous Structures
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Biochemistry
 Comparison of DNA or amino acid
sequences over time
 Most powerful evidence for a common
ancestor
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Biochemistry
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Common Cell Processes
 Cellular Respiration pathways are
similar processes in most species
 Mitosis process is the same in all
eukaryotes
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Vestigial Structures
 Structures that have
lost all or most of
their original function
in a species through
evolution
 Examples: Mole rat eyes, Manatee fingers, Human
wisdom teeth, Wale leg bone, Human Appendix
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Vestigial Structures
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Adaptations
 An inherited trait that is present in a
population because the trait helps
individuals survive and reproduce in their
environment.
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Adaptations
 Inuit people, who live in the extreme cold of the
Arctic, have short, stout bodies that conserve heat.
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Adaptations
 Masai people, who live in the arid lands of
eastern Africa, have tall, lean bodies that
disperse heat well.
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Adaptations
 Venus Fly Trap
 Lives in poor soil and acquires nutrients
from insects
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Adaptations
 Succulents have thick leaves that store
water to prevent drying out
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Adaptations
 Camouflage- blend in with the environment
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Adaptations
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Adaptations
 Mimicry- mimics or copies characteristics of others
Fly vs Honey Bee
Moth vs Lichen
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Adaptations
 King snake vs coral snake
Moth Eye Spot vs Owl Eyes
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Does Natural Selection
Occur Now?
 Yes, Bacteria reproduce very quickly
 Over decades of antibiotic use,
bacteria have developed resistance to
antibiotic medicines
 Mutations for antibiotic resistance
arise naturally and often in bacteria
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Antibiotic Resistance
 Today, nearly all bacteria are becoming
resistant to one or more antibiotics
 As bacteria become resistant, physicians
must switch to using different antibiotics.
 Example: Staph infections and Tuberculosis
are both more difficult to treat
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Misconceptions of
Evolution
 Evolution does not just add
complexity, it can take it away as well
 Example: A Tapeworm lacks many organ
systems
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Misconceptions of
Evolution
 Evolution does not “finish” with a “perfect
trait”
 The human eye has a blind spot due to
the Optic Nerve
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Evolution Can Add
Complexity
 Random mutation can lead to more
complex changes
 Example: The icefish is able to withstand
the Antarctic freeze because it has an
antifreeze protein in its blood that was
mutated from the typsinogen protein.
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2 Subgroups of Evolution
 Microevolution- refers to evolution as a
change in allele frequency in populations
 Macroevolution- refers to the appearance
of a new species over time
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Divergent
Evolution
Convergent
Evolution
See Page 383, Figure 8
new organisms
some similarities begin to
develop in same environment
common
ancestor
different
ancestries
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Adaptive Radiation or
Divergent Evolution
A special case of
divergent evolution when many niches
are available
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Gradualism vs.
Punctuated Equilibrium
Slow, even change
Long periods of no change
with bursts of rapid change
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Coevolution
 Populations are not isolated, and
often evolve in response to each
other
 Coevolution is when 2 species are
competing to “one up” each other
with adaptations
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Coevolution
 This moth species and this orchid species have
coevolved is a close relationship. The moth
feeds exclusively on the orchid, and the
orchid’s pollen is spread by the moth.
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