Transcript Warm Up 2/24

Warm Up 2/24
 Open
Ended Response Question on
Biology
 Counts as a grade!!!
 Do your best!
 Remember – Analyze, Prove, and Explain!
 Turn
in Your Reading Guide 16-1 and 16-2
to the class folder!!!
Question…..
 How
many alleles does each individual
carry for a particular trait?
 So how many alleles for tongue rolling do
we have in this class?
Question…..
 How
many alleles does each individual
carry for a particular trait? 2
 So how many alleles for tongue rolling do
we have in this class? # of people x 2
Evolution in our lives
Why Do Dogs Bark?
We tend to take it for
granted that a dog barks-but in the wild, canines
hardly ever do, instead
whining or yipping or
howling. A few studies
have examined why this
is, and the current
conclusion is that dogs
bark, well, for us.

Evolution in our lives
The most feared and panic-causing insect in New York isn't the
cockroach--it's the bedbug. In the late 1990s, after a half-century of
"relative inactivity," the bedbug suddenly reappeared, stronger than
ever. Turns out the bedbug had evolved in ways that make it much
harder to eradicate, including a thick, waxlike exoskeleton that repels
pesticides, a faster metabolism to create more of the bedbug's natural
chemical defenses, and dominant mutations to block search-anddestroy pyrethroids.
You almost have to admire the little monsters.
 Evolution
and Islands
Ever since Charles Darwin formulated his
hypothesis on how the finches of the Galapagos
Islands evolved into 13 species, islands have been a
prime target for the study of evolution. By their
very nature, islands are isolated and are essentially
a living laboratory of evolution.
 Today you will create your own Evolution Island.
Take some notes in your notebook.
 Title:
I
Population Genetics
will begin checking notebooks for grades
– do your warm-ups, take notes
Allele Frequencies and Gene Pools
 The
number and type of alleles in a population is
constantly changing.
 Evolution occurs when there is a change in the
allele frequency of a population
Evolution
 Changes
in allele frequencies can occur in a
number of different ways:
 1) Mutation
 2) Genetic Drift
3) Gene Flow
4) Natural Selection
Evolution Island
 Read the summary and answer the introduction
questions.
 Work together in your team but answer your own
questions.
 This will be turned in for a GRADE.
 You will turn in all the labs but one
be chosen to be graded.
will randomly
Evolution Island



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

How many alleles in the population?
200
How many Y alleles in the population?
130
What is the allele frequency for Y?
0.65 or 65%
A change of allele frequency in a population
is called
evolution
Evolution Island
 How
many beads make up and
individual?
2
 Why?
 Each individual has 2 alleles – each bead
represents an allele.
Allele Frequency
Sample Population
48%
heterozygous
black
16%
homozygous
black
36%
homozygous
brown
Frequency of Alleles
allele for
brown fur
allele for
black fur
percentage
RELATIVE FREQUENCY is often expressed as a __________________.
EX: In this population
Dominant B allele (black) = 40%
Recessive b allele (brown) = 60%
Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006
NOTHING to do with
RELATIVE FREQUENCY has _________
whether an allele is
DOMINANT or _____________
RECESSIVE
____________
In this population, the recessive allele is more frequent.
Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006
EVOLUTION
Mutation
 Mutation
- a heritable change in the genetic code
(DNA)
 Mutations
or harmful
are random events, they may be helpful
Evolution Telephone
 Line
up (single file) along the window-side
of the room.
 I am going to start a message by
whispering it to the first person.
 We will take turns passing the message.
 You cannot repeat the message.
Evolution Telephone
 Did
the message stay the same from
beginning to end?
 What caused the changes?
 Small mistakes in DNA (mutations) can
change populations over time, like the
mistakes in the message we passed along
EVOLUTION
Genetic Drift


Allele frequencies can change randomly through generations
because of chance. This process is called genetic drift
The appearance of coywolves in the northeastern North
America indicates a population of wolves that suffered
hunting, poisoning, habitat destruction, and near extinction
after early colonization and population of North America by
humans. This led to isolated wolves taking coyotes for mates
in Southern Canada. These hybrids survived have been able
to breed during the last 400 years leading to a population of
reproducing hybrids that have an affinity for surviving and
even thriving among human populations. This is evolution's
way of deriving new species through genetic drift.
EVOLUTION
Gene Flow
 Allele frequencies change when individuals leave a
population (migration) or enter a population.
 This movement of individuals is called gene flow.

Gene flow is the transfer of alleles from one
population to another population through
immigration of individuals. In this example,
one of the birds from population A immigrates
to population B, which has fewer of the
dominant alleles, and through mating
incorporates its alleles into the other
population.
EVOLUTION
Natural Selection
 Natural Selection - the differential survival and
reproduction of individuals in a population based on the
traits they posses
 Selection Pressure
- Those factors that influence the
direction of natural selection
Natural Selection in Action

The warrior ants in Africa are probably one of the most
impressive examples of adaptation. Within any single
colony, ants emit a chemical signal that lets the others
know they all belong to the same compound. Or, put more
simply, a signal that says "Don't attack me, we're all family."
However, warrior ants have learned how to imitate the
signal from a different colony. So if a group of warrior ants
attacks a colony, they will be able to imitate that colony's
signal. As a result, the workers in the colony will continue on,
now under the direction of new masters, without ever
realizing an invasion has taken place.
Evolution Island
 Let’s
begin the lab…