Download 7) NATURAL SELECTION: the process by which forms of life having

7) NATURAL SELECTION: the process by which forms of life having
traits that better fit a specific environmental pressure, such as predators,
changes in climate, or competition for food or mates, will tend to survive
and reproduce in greater numbers than others of their kind, thus
ensuring the continuance of those favorable traits in succeeding
generations.
8) NICHE: The role of an organism in the ecosystem. What it
eats, how it gets food, and how it interacts with other
organisms.
9) CHROMOSOME: Threadlike strands of DNA and protein
located in the cell’s nucleus; they carry the genes
10) GENE: The basic unit of heredity carried by the
chromosomes; code for features or traits of organism.
E.Q. What is Darwin’s theory on evolution?
Write two
to three
questions
here that
are
answered
by the
notes!
Evolution refers to changes in inherited characteristics of a species over time.
B) Darwin’s model of evolution
1) Darwin hypothesized that plants and animals he saw in the Galapagos
Islands originally came from Central and South America.
2) Darwin reasoned that members of a population best able to survive
and reproduce will pass their traits to the next generation; over time,
separate species can evolve.
C) Darwin hypothesis became known as the theory of evolution by natural
selection – organisms with traits best suited to their environment will more
likely survive and reproduce.
D) Variation of inherited traits within a population makes an individual different
from other members of its species; (an adaptation is a variation that makes
an organism better suited to its environment.)
1) When environmental changes occur (biotic and/or abiotic), organisms
best suited to the change will be more likely to reach the age of
reproduction. This is why variation of traits is important in a population
(for example, Darwin’s Finches).
The breeding of animals or plants by humans to
enhance one or more traits = Selective Breeding
A change in the
environment could
apply new pressure
on a population – if
the pressure
continues, in time, the
population will have
different traits than it
did before the
pressure.
Deforestation occurs for many reasons: trees or derived charcoal are used as, or sold, for
fuel or as timber, while cleared land is used as pasture for livestock, plantations of
commodities, and settlements. The removal of trees without sufficient reforestation has
resulted in damage to habitat, biodiversity loss and aridity. It has adverse impacts on
biosequestration of atmospheric carbon dioxide. Deforested regions typically incur significant
adverse soil erosion and frequently degrade into wasteland.
Beak size and shape impacted the type of food a finch
could obtain.
Small beaks good for
gathering grass seeds
Large beaks to crack
large seeds.
1
2
3
1) According to
“substantial scientific
evidence” what animal did
domestic dogs evolve
from?
1) Substantial scientific
evidence suggests that the
domestic dog evolved from
the wolf.
2) Today there are about
__ distinct breeds of dog,
most of which came into
existence in the last __ __.
2) 400, 200 years.
3) What is “the selective
breeding of organisms to
produce offspring with
desirable traits” known as?
3) The breeding of organisms
to produce offspring with
desirable traits is known as
selective breeding.
EQ: What is Darwin’s theory on evolution?
Summary
Step1: answer the essential question:
Step 2: answer each question you created for each chunk of information
Step 3: End with any past knowledge that you can combine with these notes
AND/OR
any question that you have that the notes did not answer
The origin of species – how d new species come into this
world?
Selective pressure = drought. In wet years, grass thrives
(small seeds) which favors finches with small beaks. Dry
years favors large beaked finches eating larger seeds.
The original species of finches settled on all islands. Each
island had different selective pressures that favored different
traits to develop.
On an island with sparse algal growth, small size has an
advantage because less food is needed to reach the
reproduction age.
Table of Contents (the TOC)
Unit 2, Population Diversity
Date
10/
10/29
Description
Pg #
Adaptations help populations
1
Genetics
2
We will now list some features and traits that vary in humans.
COPY THIS LIST INTO YOUR NOTEBOOK.
NB 3) Class Features/Traits
FEATURES
TRAITS
2
P7
xx
xx
xx
xx
xx
xx
xx
xx
Is there variation in our population with regards to these four features?
Which trait occurred most often for each feature?
Are any traits linked?
Typical Larkeys
What are some
of the ways that
the larkeys differ
form one
another?
Legs-short and long
Eyes- red and grey
Fur-solid, stripped,
and spotted
Tail-bushy and bare
The walkingsticks had only one feature
we investigated – color. We started with
a population of 48 walkingsticks. The
population was composed of equal
numbers of thee different traits – brown,
green-brown, and geen. In addition to
the walkingsticks there were birds that
preyed on the insects for food.
•  In what way did the population
change?
•  What factors in the environment
affected the change in the
walkingstick population?
•  How did variation help the
walkingstick population survive?
•  Was there more or less variation in
the walkingstick population after 5
generations?
•  Is there variation in the yammer of larkeys?
•  How might a predator have an impact on the
population of larkeys?
•  What trait might disappear from the population
after five generations?
Inside the nucleus is
the inheritance
messenger, DNA.
(Deoxyribonucleic
acid). DNA molecules
are huge containing
millions of atoms.
In order to fit inside the
nucleus, they are coiled
and coiled again into
structures called
CHROMOSOMES - the
______________
structures that carry the
message of inheritance.
This drawing shows the
nucleus of a cell from
our animal, the larkey.
Notice that there are
eight chromosomes,
looking a little bit like
bent hot dogs of
different lengths.
If you look closely, you
will see that these two
chromosomes are the
same, these two are
the same, and so on.
Chromosomes always
come in pairs. So our
larkey actually has four
pairs of chromosomes
rather than eight
different ones.
Now look at the dark
areas. Both
chromosomes in a pair
have dark areas exactly
the same location. The
dark areas are called
alleles.
Note: Alleles are not really dark. The dark color is used to represent
the location of the alleles on the chromosomes
The two alleles on the paired
chromosomes work together.
Together they constitute a gene.
Summary
•  Nuclei contain chromosomes.
•  Chromosomes come in
almost identical pairs.
•  Chromosomes have specific
active locations called alleles.
•  The two alleles in identical
locations on paired
chromosomes constitute a
gene
A gene (two alleles working
together) controls a trait.
This gene could be the one that
determines the larkey’s eye
color, or perhaps the pattern of
its fur. Let’s say it determines
eye color.
The larkey has four features of
interest to us. Each feature is
controlled by one gene. Each of
the four genes is on a different
chromosome (although they could have
all been on the same chromosome).
The gene location for
appendages (legs) is these
two alleles on this pair of
chromosomes. The alleles
are labeled with the letter A
for appendages.
Find the gene locations
for eye color (letter E),
fur pattern (letter F), and
tail shape (T).
Notice that some of the
alleles are labeled with
uppercase letter and
some are lowercase
letters. Both upper and
lowercase letter Es are
alleles for eye color.
Alleles don’t all have
equal influence in
determining traits. Moreinfluential alleles are
dominant alleles, and
they are represented by
an uppercase letter.
Less-influential alleles
are called recessive
alleles, and they are
represented by a
lowercase letter.
The alleles are the code
that determines the traits
of the larkeys. The chart
at the bottom is the
genetic code for one of
the 32 larkeys we
viewed previously.
The alleles for legs is aa,
eye color = Ee, fur
pattern = FF, and tail
shape = tt;
The alleles for legs is aa,
eye color = Ee, fur
pattern = FF, and tail
shape = tt;
The combination of
alleles in an organism's
chromosomes is the
organism’s genotype.
The genotype lists the
paired alleles that are
particular to that
organism.
Let’s look at the
genotype of our larkey to
see what is dominant
and what is recessive.
•  Two recessive alleles
for leg length (aa)
•  One dominant and one
recessive allele for eye
color (Ee)
•  Two dominant alleles
for fur pattern (FF)
•  Two recessive alleles
for tail shape (tt).
The parents of a Larkey both have red eyes. Is it possible for
them to produce an offspring with grey eyes? In your
notebook use a Punnet Square to prove or disprove this grey
eye question. (The alleles for eyes are E or e.)
The parents of a Larkey both have red eyes. Is it possible for
them to produce an offspring with grey eyes? In your
notebook (under NB3) use a Punnet Square to prove or
disprove this grey eye question. (The alleles for eyes are E
or e.)
Female Ee
E
Male Ee
e
E
E E
E
e
E e
e e
e