Changes Over Time

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Changes Over Time

• Honors Biology
• Mawhiney

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• Standard BIO 8 a-e The student will investigate
  and understand how populations change through
  time. Key concepts include
• a) evidence found in fossil records
• b) how genetic variation, reproductive
  strategies, and environmental pressures impact
  the survival of populations
• c) how natural selection leads to adaptations
• d) emergence of new species and
• e) scientific explanations for biological
  evolution.

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Charles Darwin

• The Father of Evolution

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History

• Darwins World (1809 - 1875)
• Height of the British colonial period.
• Beginning of the Industrial Revolution.
• New Ideas
• Taxonomy of Carolus Linnaeus
• Lyells Principles of Geology

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Binomial System of Nomenclature
Carolus Linnaeus (1707 1778)
Believed in the Fixity of Species
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Charles Lyell

• Father of Geology

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Charles Lyells view of the process of formation
of sedimentary rock
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• Suggests that sedimentary rock is very old
  therefore the species that are represented in
  this rock must also be old.
• Most fossils are found in sedimentary rock.
• Older fossils will be found below younger fossils.

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Charles Darwin
At the age of 22, he joined a 5 year expedition
aboard the HMS Beagle to map the coast of South
America
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The voyage of the Beagle
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Charles Darwins Theory of Evolution
1. Members of a population have heritable
variations.(Inheritance of traits)
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2. In a population, more individuals are produced
than the environment can support. They compete
for food and shelter. (overpopulation- struggle
for survival).
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3. Some individuals have adaptive characteristics
that enable them to survive and reproduce better
than other individuals (survival of the
fittest).
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4. An increasing number of individuals in
succeeding generations have these adaptive
characteristics (natural selection)
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Darwin described his theory in the form of a long
essay which he called On the Origin of
Species.
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Concerned about the publics response to his
ideas(remember what happened to
Galileo) Arranged to publish his work AFTER
HIS DEATH !!
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Publication of On The Origin of Species in 1859
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Charles Darwin
At age 50 (1859)
At age 65 (1874)
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Charles Darwin
Before publication
After publication
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• Through his observations made in the Galapagos
  Islands, Charles Darwin formulated a theory of
  how species change over time, called natural
  selection.

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• Natural selection is governed by the principles
  of genetics.
• The change in the frequency of a gene in a given
  population leads to a change in a population and
  may result in the emergence of a new species.
• Natural selection operates on populations over
  many generations.

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Evolution

• A change in successive generations of organisms,
  due to random mutation and changes in the
  organisms surroundings

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• Evolution takes place through a set of processes
  that include
• mutation,
• adaptation,
• natural selection,
• extinction.

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Mutation

• Genetic mutations and variety produced by sexual
  reproduction allow for diversity within a given
  population.
• Many factors can cause a change in a gene over
  time.

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Mutation

• Mutations are important in how populations change
  over time because they result in genetic changes
  to the gene pool.

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• Mutations are inheritable changes because a
  mutation is a change in the DNA code

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Mutation- a change in the DNA

• A mutation may result in a
• 1. favorable change or adaptation in genetic
  information that improves a species ability to
  exist in its environment

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Mutation- a change in the DNA

• 2. an unfavorable change that does not improve a
  species ability to exist in its environment.

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Mutation- a change in the DNA

• 3. in a change in the genetic information that
  neither harms nor helps the species.

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Adaptation

• Adaptations are structures, functions, or
  behaviors that enable a species to survive.

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Adaptation

• Depending on the rate of adaptation, the rate of
  reproduction, and the environmental factors
  present, structural adaptations may take millions
  of years to develop.

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Natural Selection

• the survival and reproduction of the individuals
  in a population that exhibit the traits that best
  enable them to survive in their environment.
• The Survival of the Fittest

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Natural Selection

• Populations produce more offspring than the
  environment can support.

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Natural Selection

• The unequal ability of individuals to survive and
  reproduce leads to the gradual change in a
  population, generation after generation over many
  generations.

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Natural Selection

• Organisms with certain genetic variations will be
  favored to survive and pass their variations on
  to the next generation.

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• These five canine species evolved from a common
  ancestor through natural selection

African wilddog
Coyote
Wolf
Jackal
Fox
Thousands tomillions of yearsof natural
selection
Ancestral canine
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When humans choose organisms with specific
characteristics as breeding stock, they are
performing the role of the environment

• This is called artificial selection

Example of artificial selection in plants five
vegetables derived from wild mustard
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Artificial Selection in Animals Dog Breeding
German shepherd
Yorkshire terrier
English springerspaniel
Mini-dachshund
Golden retriever
Hundreds tothousands of yearsof
breeding(artificial selection)
Ancestral dog
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The evolution of insecticide resistance is an
example of natural selection in action
Chromosome with geneconferring resistanceto
insecticide
Additionalapplications of thesame insecticide
willbe less effective, andthe frequency
ofresistant insects inthe populationwill grow
Insecticideapplication
Survivor
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Extinction

• no longer in existence "the extinction of a
  species"

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• If a species does not include traits that enable
  it to survive in its environment or to survive
  changes in the environment, then the species may
  become extinct.

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Individuals die, a species becomes extinct.
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• Individuals of a population exhibit a range of
  variations in a trait as a result of the
  variations in their genetic codes.

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• The evidence for evolution is drawn from a
  variety of sources of data, including
• the fossil record,
• radiometric dating,
• genetic information,
• the distribution of organisms,
• anatomical and developmental similarities across
  species.

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Fossil Record

• Although there is not a complete record of
  ancient life for the past 3.5 billion years, a
  great deal of modern knowledge about the history
  of life comes from the fossil record.

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• The study of fossils provides strong evidence for
  evolution.

Petrified Trees
Hominid skulls
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Fossilized organic matter in a leaf
Ammonite casts
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Ice Man
Scorpion in amber
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Distribution of species

• Most marsupials live in Australia
• This supports the theory of continental drift.

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Distribution of species
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Geographic isolation can lead to speciation
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Species

• Organisms that can breed and produce FERTILE
  offspring.

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Adaptive Radiation

• where species all deriving from a common ancestor
  have over time successfully adapted to their
  environment via natural selection

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Homologous Structures 

•  Body parts in different organisms that have
  similar bones and similar arrangements of
  muscles, blood vessels, and nerves and undergo
  similar embryological development, but do not
  necessarily serve the same function e.g., the
  flipper of a whale and the forelimb of a horse.

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Homologous Structures
Human
Cat
Whale
Bat
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Vestigial Structures

• Features that apparently serve no function in an
  organism and are allegedly holdovers from an
  evolutionary past. Such features, though no
  longer useful, are presumed to have been useful
  in ancestral species.

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EX. Wings in flightless birds
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EX. appendix in humans, whale pelvis, tiny snake
pelvic and limb bones, and the eyes in
cave-dwelling salamanders and fish that are
completely blind.
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Developmental Similarities

• Many species have very similar embryonic
  development.
• The embryo of a chicken, a pig, and a fish are
  almost identical at certain points in their
  development.

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• Stephen Jay Goulds idea of punctuated
  equilibrium proposes that organisms may undergo
  rapid (in geologic time) bursts of speciation
  followed by long periods of time unchanged.
• This view is in contrast to the traditional
  evolutionary view of gradual and continuous
  change