Transcript Today: 5/29/2000

Today’s Plan: 10/15/09
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Bellwork: Pre-lab (15 mins)
Begin Natural Selection labs (40 mins)
Notes (25 mins)
Pack/Wrap-up (last few mins of class)
Today’s Plan: 10/16/09
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Bellwork: Vocab Quiz (20 mins)
Finish Notes(25 mins)
Finish Lab (the rest of class)
Pack/Wrap-up (last few mins)
Today’s Plan: 10/19/09
• Bellwork: Finish Natural Selection (15
mins)
• Q&A Time (10 mins)
• Natural Selection Quiz (as needed)
• If you finish early, work on missing
homework, finishing the lab, or getting
ahead (the rest of the period)
• Pack/Wrap-up (last few mins of class)
Today’s Plan: 4/7/08
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Bellwork: Finish Notes (15 mins)
Q&A Time (5 mins)
Change Through Time Quiz (as needed)
When you finish, Finish the natural
selection labs, then work on the
classification Intro Activity (the rest of the
period)
• Pack/Wrap-up (last few mins of class)
Evolution Historical Perspective
• Before Darwin:
– Jean Baptiste de Lamarck believed that
organisms could change their bodies to fit the
environment. Giraffe example. What is wrong
with this idea?
– Charles Lyell was building roads through rock,
and discovered evidence that the earth was
much older than the church believed. Found
fossils in strange places
Charles Darwin
• Originally trained for the church
• Studied science at school, and was a
member of several scientific societies
(Geology, zoology, etc.)
• Read Lyell’s work
• Took a job on the HMS Beagle as a
naturalist traveling to South America and
the Galapagos Islands for 5 years.
Darwin (cont.)
• Wasn’t the only one working on how species
change over time. Another naturalist, Alfred
Russel Wallace, was working with insect
populations and simultaneously &
independently had the same ideas as Darwin.
• Darwin studied his collections and evidence
over a very long period of time. When his
hypothesis was formulated, he waited to
publish his findings until he realized that
Wallace was about to publish and get all of
the credit.
Darwin’s Evidence
• Same species living on different islands w/
different habitats had different adaptations.
• Noticed homologous (seen in different
groups of descendants-ex. Hands/feet in
primates) and analagous(same structure but
different function structures in animals-ex.
Wings/forelimbs).
• Had read Thomas Malthus’ which said that
food produces arithmetically while
populations produce geometrically-There
will be competition for resources.
More Evidence
• Vestigial Structures-once had a function but
now reduced in size and function
• fetal development
• Fossil evidence
Natural Selection
• In On the Origin of Species, Darwin
proposed “descent with modification” as a
mechanism for species change. This later
became known as natural selection.
• Organisms with favorable adaptations will
survive to reproduce longer and therefore
pass on more favorable traits and their
descendants will outnumber others. This
takes lots of time. Eventually, as a result of
this, species change (much different from
Lamarck)
Types of Natural Selection
• Stabilizing-selecting for individuals with
“middle” phenotypes.
• Disruptive-selecting for individuals with
phenotypes in the outer limits
• Directional-selecting for individuals with
phenotypes toward one limit or the other
• Artificial-humans select for traits using
selective breeding
Making Species
• Requires isolation and evolution in different
directions
• Originally thought to be slow and gradual
(gradualism), now known to be stable, with
short bursts of evolution (punctuated
equilibrium)
• Isolation can be because of a physical or
behavioral barrier.
– Physical requires geographic isolation.
– Behavioral requires non-mating because of
unrecognizable courtship rituals.
Directions of Evolution
• Species can evolve from a common
ancestor in different directions (adaptive
radiation), or come from different ancestry
and move in similar directions (convergent
evolution)
• Coevolution-evolution at the same time in
response to another species
– the red queen hypothesis
Genetic Equilibrium
• Evolution works on genes to change whole species
or populations of species over time, not on
individuals.
• Gene Pool=all of the genes of a population
• Gene frequency=# or % of a certain allele in a
population (p+q=1, p=dominant, q=recessive)
• Using the present phenotypes, we can sometimes
calculate the frequency of genes in the population.
This helps us determine if populations are
evolving or in equilibrium.
• Hardy-Weinberg Theory for equilibrium:
– p2+2pq+q2=1
– where p^2=homozygous dominant,
q^2=homozygous recessive and pq=heterozygotes
About Hardy-Weinberg
• Theoretical and requires certain conditions
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No immigration and emigration
Random mating
No net mutation
No selection
Large population
• Has been shown to exist over time when the above
conditions are met, however many populations
don’t exist under these stable conditions
• In other words, if the theory is an inequation,
population change is occurring.
Changes in equilibrium
• Selecting mechanisms cause gene frequencies to
change.
• Immigration and Emigration mean that organisms
bring in and take out new genes, which influences
frequencies.
• Catastrophic events that drastically reduce the
gene pool also cause change (this is one example
of genetic drift, which effects small populations
more than large ones. Why?)
Disclaimer
• Evolution is a theory. It is not religion, not law, and not a
hypothesis.
• Evolution is based on scientific principles and evidence.
Creationism is not based upon these principles and is
therefore not a science.
• Belief in God is based on faith, not science. Faith and
science are two very different matters. Science does not seek
to prove or disprove the existence of God. You do NOT have
to believe in evolution, but it is a requirement of this course,
set by the state. You must therefore learn it, and will be
tested on it on the EOC.
• If you have faith-based questions, I urge you to seek the
advice of a minister, rabbi, priest, etc. This is their area of
expertise, and they are far more qualified than I to help you.
• If you have science-based questions, you are welcome to
speak to me, because this is my area of expertise.
Practice EOC Question
• Which statement describes an exception to
the cell theory?
– Cells arise from previously existing cells
– The Cell is the basic unit of function in animals
– Mitochondria and chloroplasts can reproduce
within the cell
– The cell is the basic structure of plants
Practice EOC questions:
• Which of the following is a reactant in
photolysis?
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Electron
Oxygen
Proton
water
• After performing a monohybrid cross, it is
important to analyze the results with a Punnett
square. Each box of a Punnett square
represents–
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A possible phenotype
A possible genotype
One individual
Two possible genotypes
Practice EOC question
• Consider the following:
– Mitochondria resemble bacteria
– Mitochondria contain DNA and ribosomes
– The ribosomes in mitochondria resemble those
in bacteria
• What would be a logical interpretation of
these findings?
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There are many coincidences in nature
Mitochondria might one day become bacteria
Mitochondria evolved from a type of bacteria
Cells evolved from mitochondria