Transcript of Warm Up With your partner, write a sentence (20 words or less) using two of the following terms to...
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- Warm Up With your partner, write a sentence (20 words or less)
using two of the following terms to show your knowledge of genetic
engineering: * Transgenic Organisms, Recombinant DNA, Recombinant
Bacteria, Selective Breeding, PCR, Gel Electrophoresis, Genetically
Modified
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- Changes Over Time SOL: BIO 8 a-e
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- Theory of Evolution Science is made up of many ideas, theories,
and laws. Many of these ideas have gone through many changes
throughout the years. Our job as life-long learners is to examine
all the evidence concerning a particular topic. Evolution is part
of the Core Knowledge curriculum for Biology. The origin of life is
a sensitive subject for many people. There are many theories
concerning the change in things over time. You may hold a different
view than what will be presented as part of the Core Knowledge
curriculum. Out goal is to explore the theory of evolution from a
scientific standpoint, not to discount any other theories on the
origin of life.
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- Charles Darwin The Father of Evolution
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- History During Darwins Time(1809 - 1875) most people believed
the Earth was only a few thousand years old. They also believed
that neither the planet nor its living species had changed over
that thousand years Darwins ideas were shocking and radical
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- HISTORY Darwin was influenced by many explorers and great
thinkers who were starting to challenge views about the world Some
new ideas that were influential to Darwins discoveries were:
Taxonomy of Carolus Linnaeus Lyells Principles of Geology
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- Carolus Linnaeus (1707 1778) Believed in the Fixity of Species
or that all species have remained unchanged throughout the history
of the Earth. Binomial System of Nomenclature
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- Charles Lyell Father of Geology Suggested that layers of rock
form slowly and are moved up by the forces beneath Earth His
theories suggested that the Earth is millions of years old.
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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 Lyell How did his ideas influence Darwin? If the Earth
could change over time, might life change as well? The changes
(evolution) Darwin would later suggest would have been possible
only if the Earth were extremely old
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- Knowledge Check Who was Linnaeus? Who was Lyell? If Lyell
looked at fossils in a cross section of sediment, would the fossils
more towards the surface be older or younger than those below?
Why?
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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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- Darwins Voyage Darwin explored and collected specimens whenever
The Beagle landed ashore He noticed the diversity of organisms as
he traveled and noticed how animals and plants seemed remarkably
suited for their environment
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- One stop that was important to the development of Darwins
theories was the Galapagos Islands These islands are just west of
South America and were particularly interesting because although
they are very close together, they have dramatically different
climates Because they were formed by volcanoes, they range from
barely at sea level to 1500m above sea level
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- Darwins Observations Land Tortoises Shell shape varied from one
island to another Hood Island Tortoise: Long neck and curved shell
allows this tortoise to reach the high vegetation
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- Isabela Island Tortoise: Dome shaped shell and short neck as
vegetation is closer to the ground
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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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- Knowledge Check What was the name of the boat on which Darwin
traveled? What unique observation did Darwin make about the
landscape of the Galapagos Islands? What observations did Darwin
make regarding the organisms living on the island?
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- Charles Darwins Theory of Evolution by Natural Selection
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- 1. Heritable Variation: Members of a population have heritable
variations. (Inheritance of traits)
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- 2. Overpopulation: 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. Survival of the Fittest: Some individuals have adaptive
characteristics that enable them to survive and reproduce better
than other individuals (survival of the fittest). Fitness: Ability
of an organism to survive and reproduce
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- 4. Adaptation: An increasing number of individuals in
succeeding generations have these adaptive characteristics
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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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- He finally decided to publish his essay, 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 publicationAfter publication
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- Knowledge Check What was the name of Darwins book? On what
islands did Darwin make observations that lead him to develop his
ideas about natural selection? Explain how natural selection can be
observed in a population.
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- How does Evolution work? Evolution is governed by the
principles of genetics It is a change in successive generations of
organisms, due to: 1. random mutation 2.Adaptation 3.Natural
selection 4.Extinction
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- MUTATIONS Genetic mutations and variety produced by sexual
reproduction allow for diversity within a given population.
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- Mutations are inheritable changes because a mutation is a
change in the DNA code
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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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- A mutation may result in change that is: 1. Favorable; improves
a species ability to exist in its environment
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- 2. Unfavorable; does not improve a species ability to exist in
its environment.
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- 3. Neutral; 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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- Knowledge Check What are the 3 types of changes that mutations
can result in? What is an adaptation? (HINT: It is a NOUN)
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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 This leads to competition for resources and
individuals 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 wild dog Coyote Fox WolfJackal
Thousands to millions of years of 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 terrierEnglish springer spaniel Mini-dachshund Golden
retriever Hundreds to thousands of years of breeding (artificial
selection) Ancestral dog
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- Extinction 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, and eventually the species becomes
extinct.
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- Knowledge Check What is another name for natural selection?
What is artificial selection? What can lead to extinction in a
population?
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- WARM UP Explain how each process below can lead to evolutionary
change. Heritable Variation Overpopulation Survival of the Fittest
Adaptation
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- EVIDENCE FOR EVOLUTION
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- Darwin argued that living things have been evolving on earth
for millions of years, and evidence could be found in: the fossil
record, the geographical distribution of species homologous
structures of living organisms Similarities in early development
(embryology)
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- Fossil Record Darwin saw fossils as a record of the history of
life on Earth By comparing fossils from older rock layers with
fossils from younger layers, scientists could document the fact
that life on Earth has changed over time.
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- The study of fossils provides strong evidence for evolution.
Hominid skulls Petrified Trees
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- Scorpion in amber Ice Man
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- Distribution of species On his voyage, Darwin discovered many
species of finches, all similar but distinctly different from one
another based on where they were found He eventually concluded that
these finches had descended with modification from a common
ancestor as populations adapted to different environments (adaptive
radiation)
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- Allopatric Speciation Geographic isolation/separation can lead
to speciation (emergence of a new species)
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- Homologous Structures Structures that have different mature
forms but develop from the same embryonic tissues are called
homologous structures; these structures provide support to Darwins
theory of evolution Darwin noted striking anatomical similarities
among the body parts of animals with backbones; the limbs of
reptiles, birds and mammals vary in form and function, yet they are
all constructed from the same basic bones
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- Homologous Structures HumanCatWhaleBat
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- Not to be confused with Analagous Structures Structures in
different species that have the same appearance, structure, or
function but have evolved separately, thus do not share a common
ancestor. For example, birds and some insects have wings and both
species use these for the same function, to fly. However, birds and
insects evolved separately; they do not share a common
ancestor.
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- Vestigial Structures Homologous structures 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. They are
vestiges, or traces of homologous structures 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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- Why do these structures hang around ? Although they serve no
purpose, one argument states that since these organs do not affect
an organisms ability to survive and reproduce, natural selection
would not cause their elimination.
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- Similarities in Embryology 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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- Summary of Darwins Theory Individual organisms differ, and some
of this variation is heritable Organisms produce more offspring
than can survive, which leads to competition for limited resources
Organisms best suited to their environment survive and reproduce
most successfully (and pass their traits on) causing a species to
change over time (natural selection) Species alive today are
descended with modification from ancestral species