Transcript File - Biology and Botany/Ecology Class!

Homework:
Read this
Chapter
Introduction
Animation
John Levasseur
Springfield Central High School
Biology
1)
2)
3)
4)
Discuss the history of the Theory of
Evolution.
Explain why Evolution is the key concept
and central theme of the science of life.
Discuss the four factors that Darwin
recognized for Evolution via natural
selection.
What is the significance of
Darwin's Galapagos finches? (This question comes
right from the 2007 Biology MCAS.)
Evolution is the key concept in biology and one of the greatest ideas in
science history. Every unit and every topic that we study in biology relates
to the concept of evolution.
• Galileo's challenging the Aristotelian's view
The Greatest
of the universe as up held by the church.
Scientific Advances
Discuss the great
scientific discoveries
and why evolution is
the key concept of
biology.
• Newton's Three Laws of Motion.
•Law of Conservation of
Mass by Lavoisier
•Dalton's Atomic Theory
• Darwin's Theory of Evolution via Natural Selection
• Einstein's Theory of Relativity
The Ancient Greeks
The earliest recorded proponent of evolution was an ancient
Greek philosopher Anaximander who lived 2500 years ago.
The great Greek philosopher and father of Western
science, Aristotle is credited by Charles Darwin as one who
pointed the way toward the explanation of life's unity
through natural selection.
Eighteenth Century Scientists
Georges-Louis, Comte de Buffon (1707 - 1788) was an
early scientist who questioned the similarities between
apes and humans and offered common ancestry as an
explanation.
Jean-Baptiste Lamarck (1744 - 1829) Charles Darwin
himself credited Lamarck's writings and ideas as an
early inspiration.
Discuss the
history of the
theory of
evolution.
Erasmus Darwin (1731 -1802), Charles Darwin's
Grandfather, Erasmus Darwin was a famous poet and
naturalist. Erasmus Darwin's poetry was known for its
use of sexual and natural imagery; Erasmus Darwin used
poetry to state his view that life had evolved.
Nineteenth Century Scientists who formed the idea of Natural Selection
Alfred Wallace (1823 - 1913), thought of natural
selection independently of Charles Darwin. The first
paper published on the topic of evolution by natural
selection was jointly written by Darwin and Wallace.
Charles Darwin (1809 - 1882) The publication of
Darwin's book On The Origin of Species
revolutionized the scientific view of life. Darwin
called his explanation of the way evolution works
"Natural Selection".
Discuss both Darwin and Wallace and the story of
how each explained evolution as a function of
“Natural Selection”.
After years of observations and experiments, Charles Darwin proposed the
Theory of Evolution via Natural Selection.
The Beagle Voyage and The Galapagos Finches
As a young man, Darwin had sailed around the world on a voyage
of exploration aboard the ship HMS. Beagle collecting fossils and
specimens of organism from the different places he visited.
•Discuss the aspects of Darwin's
life story that led him to the
Theory of Evolution.
•Discuss Darwin’s Beagle
voyage.
Charles Darwin and Natural Selection (Cont.)
The Beagle Voyage and The Galapagos Finches
Of key importance was the collection of birds, (finches) Darwin made in
the Galapagos Islands.
Darwin collected a variety of finches from the different Galapagos Islands.
Darwin noticed that the form of the beaks
from the different species of finches that
he collected varied from Island to Island
and from feeding habit to feeding habit.
Darwin reasoned that the Galapagos
Islands, which were geologically new
islands, must have been populated by a
few common ground finches from the
South American mainland.
This population of the common ground finch must have diversified to
survive on different types of food in the new environment of the Galapagos
Islands. Adaptation for survival in the Galapagos Islands produced the
variety of different species Darwin found there.
Why was Darwin’s stop at the Galapagos Islands so critical to the
development of Darwin’s theory of Natural Selection?
What is the significance of Darwin's finches?
Darwin realized the struggle for survival due to the difficulties (or selection
pressure) caused by nature must be selecting for heritable trait variations
that will allow one organism within a population to out-reproduce the other
members of the population. Darwin published these ideas in his book On
The Origin Of Species in 1859.
New species must therefore arise by natural environmental selection
pressure which forces organisms to adapt to a dynamic or changing
environment or become extinct.
Darwin had been collecting data about this theory since the late
eighteen thirties and initially wrote an outline of his idea in 1844.
However, it was not until Alfred Wallace wrote to Darwin with a similar
explanation for evolution that Darwin was motivated to write his now
famous book the On The Origin Of Species in which Darwin forever
changed the way science views life.
What is “Natural Selection”?
Who was Alfred R. Wallace?
Explain the Theory of Natural
Selection.
Are evolution and Natural
Selection synonymous?
Imagine a population of beetles:

Individuals within a
population have variation. 
2. Some variants are “better”
than others.
3. The traits are heritable.
4. The “better” individuals will
have more success
reproducing and more
offspring.

Natural selection is one of
the basic mechanisms of
evolution along with:
◦mutation
◦migration

◦genetic drift
◦Symbiosis
There is variation in traits.
There are green and brown beetles.
1.
http://biologyreview.tumblr.com/
There is differential reproduction.
Since the environment can’t support unlimited
population growth, not all individuals get to
reproduce to their full potential. In this
example, green beetles tend to get eaten by
birds and survive to reproduce less often than
brown beetles do.
There is heredity.
The surviving brown beetles have brown baby
beetles because this trait has a genetic basis.
End result:
The more advantageous trait, brown
coloration, which allows the beetle to have
more offspring, becomes more common in
the population.
See BioReview for These notes
Also review Comparison between Lamarck and Darwin
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1. Competition for survival and opportunities to
reproduce between the members of a population.
2. Variation of traits between organisms within a
population.
3. The traits that have variation within the
population must be heritable traits, that is the
traits must be able to be passed to the next
generation.
4. Organisms must be able to better adapt to
their environment by the inheriting beneficial
variations of these heritable traits.
Explain Darwin’s 4 Factors
For Natural Selection.
List the 4 factors for
natural selection.
An essay by theologian and economist Thomas Malthus
helped Darwin see that members of a population
compete with each other for survival.
Malthus wrote in his, An Essay On the Principle of
Population, that humans are in a competition for
limited resources and that over-population increases
this competition which in turn leads to human
suffering and vice.
Darwin recognized that organisms in nature are in a competition for
limited resources and that there is a tendency for organisms to overproduce offspring or seeds to ensure survival.
Darwin knew that due to competition between organisms within a
population some members of the population will be more successful than
other members.
•What is “Malthusian Doom”?
•How did “Malthusian Doom” help both Darwin and Wallace see that
competition within a population lead to natural selection?
•Where do we see Malthusian Doom today?
•What are the strengths and weaknesses of the idea of Thomas
Malthus?
Fitness is the term Darwin used to describe the ability to compete for
resources and opportunities to reproduce.
The fitness of an organism determines the ability to out-compete similar
organisms in the same population for survival and reproduction.
Competition means there will be winners and losers.
For Darwin the "winners" were those organisms in a population better
suited for survival in a particular environment which allowed them to have
more of their offspring survive than a member of the population less
suited for survival.
Competition for survival between members of a population is the
first factor needed for evolution via natural selection.
What is “fitness” in a
Darwinian sense?
It is clear to all observers of nature that organisms of the same species are
not identical.
Examples: No two oak trees,
(Quercus alba), nor any two
whitetail deer, (Odocoileus
virginianus), or any
individuals of other species
are identical.
Here is an amazing fact.
Variation of any trait between members of any population will always
graph into a normal distribution of the trait (a bell-curve) if you sample
enough members of the population.
•What is variation?
•Why will any trait graph into a
bell curve?
Let’s see if we can test the statement that variation of any trait between
members of any population will always graph into a normal distribution of
the trait (a bell-curve) if you sample enough members of the population.
Think of our population as Central High School sophomores
You can pick any random trait, like height and graph that trait.
Is there variation in the height of the sophomores? Of course there is.
There will be a tallest and a shortest and every one else in-between
with the majority of sophomores having some average height.
How tall will the tallest be? How tall will the shortest be?
What will be the
average height?
Amazing! The data of
our sophomores'
heights fits this
graph.
Explain this
demonstration of a
trait always
graphing into a bell
curve.
Remember that Darwin had
collected finches from the
Galapagos islands, and these
birds inspired him to think that
the variety of finch species found
in the Galapagos was due to
variations of one species of finch
evolving into a variety of similar
species.
Here is a graph actually generated from data collected on the beak
depths of a population of finches in the Galapagos Islands.
Notice how real data
Here we see a
does not fit perfectly to
the results of
the mathematical ideal,
survey of one
but the data does
species of
follow the pattern.
finch from
those same
islands.
Explain this demonstration of Darwin’s
Finches beak size graphing into a bell curve.
Variation between members of a population is the second factor needed
for evolution via natural selection.
Variation within a population not only exists but it can be measure and
graphed.
Organisms within a population have variations.
Sometimes a variation helps an organism obtain
necessities for survival within the organisms’
environment.
Other times a variation limits an organism’s
ability to obtain the necessities of life.
While most times a variation neither helps
nor hurts an organism’s ability to obtain
necessities.
Discuss how variation within a
population can lead to natural
selection?
Organisms have the means of passing
traits from one generation to the next.
Heritable traits is the third factor
needed for evolution via natural
selection.
The variations between organisms within a population are inheritable
traits and are passed on from one generation to the next.
If an organisms within a population has a heritable variation that
increases that organism’s change for reproduction. Then generation after
generation that variation will become.
Note that Darwin recognized this fact
but did not know how the inheritance
of traits worked. This was not
understood until after Mendelian
genetics was adapted.
•Explain why heritable traits is one of
Darwin's prerequisites for Natural
Selection.
Before we consider the ability of populations of organisms to adapt
naturally to their environment , we will consider the ability of humans to
select for traits in agricultural crops and animals.
Artificial Selection
Another observation that sparked Darwin's thinking was the breeding of
farm animals and agricultural crops. Darwin was a pigeon breeder and
was interested in livestock and dogs that had been bred by humans.
Darwin knew that farmers select breeding
mates by choosing traits that the breeder
wants to enhance in the next generation.
Darwin called the selection
of traits done by breeders
artificial selection.
Explain artificial selection.
Notice the variation in these two types of dogs, (Canis
domesticus, aka. Canis lupus familiaris).
Dogs were bred by humans from the
wolf, (Canis lupus),
Consider if these dogs
would be in the same
species if they were in
nature and not bred by
humans from the wolf.
What differences in the two dogs above do you notice? Remember both
were bred by humans from a common ancestor, the wolf (Canis lupus)
Would these two dogs be the same species in nature? Would they mate
to produce fertile offspring?
Darwin questioned that if humans can select traits and breed animals to
be better adapted to some human want such as gentle disposition, more
meat, better eggs; why can't nature select for traits better suited for
survival in a particular environment, such as warmer coat, better
camouflage, beak form better suited for acquiring food?
Explain why these dogs bred by human would be separate species
if found in nature and not artificially selected for.


Why do
organisms
need to adapt
to their
environment?

Natural Selection
◦ Darwin realized the struggle for
survival due to difficulties (or
selection pressure) caused by
nature must be selecting for trait
variations that will allow one
organism within a population outreproduce the other members of
the population.
◦ New species must therefore arise
by natural environmental selection
pressure which forces organisms to
adapt to a dynamic or changing
environment or become extinct.
Natural selection is a mechanism of
change in populations that allows for
adaptation to better survive in a
particular environment. Nature
selects the trait by chance and by
reproductive success, (fitness).
A population’s change over time
through adaptation to a dynamic
environment is the fourth factor
needed for evolution via natural
Animation
selection.
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If the heritable trait variations within a
population are normally distributed then there
must be three possible changes to the
population due to natural selection.
Recall that all random variations of any trait
can be measured and graphed in a bell curve.
The three forms that nature can select for on a
population are:
◦ Stabilizing: all members become more alike
because the extremes of variation
disappear.
◦ Disruptive: members of one population
diverge because the average form of the
trait is detrimental for survival.
◦ Directional: members of a population
appear very different over time since one
extreme is more beneficial for survival than
the other extreme driving the population to
have a new average for the trait.
Animation
Explain stabilizing, disruptive and directional selection.
http://en.wikipedia.org/wiki/Genetic_drift



Genetic drift or allelic drift is the change in the frequency of a gene
variant (allele) in a population due to random sampling.
◦ One gene may have multiple forms, called alleles.
Genetic drift is an evolutionary process, which leads to changes in allele
frequencies over time.
◦ Genetic Drift may cause gene variants to disappear completely, and
thereby reduce genetic variation.
 In natural selection gene variants become more common or less
common depending on their reproductive success.
◦ The changes due to genetic drift are based on happenstance and not
driven by environmental or adaptive pressures, and may be beneficial,
neutral, or detrimental to reproductive success.
The effect of genetic drift is larger in small populations, and smaller in large
populations.
◦ Luck effects small populations more than large populations
See
Tutorial

We see
bottlenecks
in
endangered
species,
migration to
new land

masses like
Hawaii or the
Galapagos or
Pennsylvania.


http://en.wikipedia.org/wiki/Founder_effect
The Founder Effect is the
loss of genetic variation that
occurs when a new
population is established by
a very small number of
individuals from a larger
population.
As a result of the loss of
genetic variation, the new
population may be
distinctively different, both
genetically (DNA) and
phenotypically (appearance),
from the parent population
from which it is derived.
In extreme cases, the
founder effect is thought to
lead to the speciation and
subsequent evolution of new
species.
The founder effect is a
special case of genetic drift
Homework:
Read this Chapter
The Modern Synthesis between Darwin's Natural Selection and Contemporary
Understanding of DNA
Ecology
In Darwin's day, biology, geology, and environmental science were all
wrapped into one study called "Natural History". Today "Natural History"
would be called "Ecology" in which we study how organisms interact with
each other and their environments. Our understanding of how organisms
interact and depend on each other and the environment has grown greatly
since Darwin's era. Darwin used competition as the interaction driving
evolution; however, today scientists look at other interactions, such as
cooperation, as a relationship that drives evolution.
Biochemistry
The understanding of the chemistry of living things has been incredibly
expanded since the time of Darwin. The discovery of DNA and how that
molecule codes for the proteins that cause the variations between members
of a population alone stands as a great advancement in science since
Darwin.
Animation
•What are ecology and biochemistry?
•What is the Modern Synthesis?
Cell Biology
A great understanding of the cell and cell organelles have allowed scientists
to explain the origins of common ancestry more fully.
Genetics
Darwin did not know the mechanism of how organisms inherit their traits,
genetics.
Anatomy and Physiology
Discoveries in the structure and development of organisms shine light on the
unity of life.
Knowledge From the Other Natural Sciences that Relate to Evolution
Fossil discoveries and the ability to date fossils have added support to
Darwin’s Theory.
Note how ecology, biochemistry, cell biology, genetics,
anatomy and evolution are our remaining units this year.
•What are: cell biology,
genetics, anatomy and
physiology?
•What will we be studying
this year?
We can think of the class as a cycle.
Talk about what we’re going to talk about, talk
about it then talk about what we talked about
Introduction
evolution
Ecology
Anatomy
and
Physiology
Explain how
this biology
class can be
thought of
as a cycle.
Chemistry
of life
Genetics
Cells
DNA is a molecule that stores information chemically about how to build proteins; proteins
are the molecules in living things that really do the work of life. DNA has sections of
information known as genes that hold the information for just one protein. DNA and
genes can change through copying mistakes called mutation, which cause changes in
proteins.
The changes in the proteins cause changes and variations in organisms. Sometimes those
variations will be a benefit to the organism. Other times a variation will be a detriment to
the organism. Most times a variation will neither help nor hurt an organism.
Organisms in a population compete for resources and opportunities to pass on genes
(have offspring). Those organisms within a population with the genetic phenotype that
produces the protein variations that benefit or increase the organism’s fitness (ability to
gather resources and on pass genes), will have more offspring than those organisms with
variations that are less favorable for survival in their environment.
The beneficial variations due to increased number of the genes that cause those variations
will become more frequent in the next generation.
Evolution happens as a population’s genes and the gene frequencies change over time. A
change in genes means a change in proteins, which could allow for changes in the
organism's biochemistry or appearance. These changes have been the result of nature
favoring one type of gene, (protein) over another for survival in a certain
environment. Evolution causes organisms to become better adapted for survival in an
environment.
Explain this paragraph in your own words.
Are biology and science the same thing?
What is science?
What are the studies and explanations in science limited to?
Why can the study of science be a paradox?
What is the key concept of science?
What does the word dynamic mean?
What things in nature are dynamic?
What is biology?
What is the key concept of biology?
Should we include supernatural topics in the study of natural science?
Who was Stephen Jay Gould and what is his principle of NOMA?
Who was Charles Darwin?
Was Darwin the first person to propose that living things evolve?
What is artificial selection?
What is natural selection?
What is the HMS Beagle and how does it relate to the topic of evolution?
What are the four factors need for evolution via natural selection?
What is the significance of Darwin's finches from the Galapagos islands?
Answer at least three of these questions.