Transcript Evolution Pt 2

Unit: Evolution and
Classification
Objectives:
1. Define and describe natural selection.
2. Explain how adaptations and genetic changes lead to
speciation over time.
2/2 Bell Work
Mr. Dodgers is arranging a world hacky sack
tournament. There are 657 contestants, and it is a
single-elimination tournament. There are an odd
number of people so one player gets a bye on the first
round and automatically advances.
 How many matches will he have to arrange to
determine the champion?
2/2 Schedule
 Grade Reports and Letter Home due THURSDAY
 Natural Selection Simulation
 Finish Gen 3 today if possible
• Open House WEDNESDAY 5-7
Assignments:
1. Why It Matters – Dogs LATE
2. Beans Evolution Lab and Report LATE
3. Dir Rdg Ch 16 “Evolution” due TODAY
4. Grade Reports and Letter Home due THURSDAY
2/3 Bell Work
Take a close look at the following sentence.
“Please give $1 to help stop child abuse in the front office.”
 Fix the sentence to reflect what the author probably
intended.
2/3 Schedule
 Natural Selection Simulation
 Finish testing today if possible
• Open House TONIGHT 5-7
Assignments:
1. Why It Matters – Dogs LATE
2. Beans Evolution Lab and Report due LATE
3. Dir Rdg Ch 16 “Evolution” LATE
4. Grade Reports and Letter Home due THURSDAY
2/5 Bell Work
Put in math symbols to make the following equation true.
18 X 12 / 2 + 3 = 111
2/5 Schedule
 Notes Ch 17.1 “Genetic Variation”
 Work
 Natural Selection Sim
 Natural Selection Wksht due MONDAY
 Missing assignments
Assignments:
1. Dir Rdg Ch 16 “Evolution” LATE
2. Grade Reports and Letter Home due TODAY
3. Natural Selection Simulation due MONDAY
4. Natural Selection Wksht due MONDAY
Ch 17.1 “Genetic
Variation”
Objectives
1. Describe how microevolution is studied.
2. Describe how phenotypic variation, genetic variation,
and genetic change are measured.
1. Review where phenotypic variation originates.
Breeding “Improved”
Goats
Imagine that you are in charge of a goat ranch. The cost of
fencing is really high, so you must implement a breeding
program that will produce shorter-legged goats within the
next 20 years. Write down how you would meet this goal.
Population Genetics
Microevolution : evolution of populations at the genetic level
 Studying changes in numbers and types of alleles is
population genetics.
Phenotype Variation and
Change
Gene Pools: particular combination of alleles in a
population at any one point in time.
 Variation and change are measured in terms of the
frequency of alleles.
 A frequency is the proportion of a group that is of one type,
can be tracked over time.
Phenotypic Variation
Phenotype variation: traits have a variety of “looks”
Depends on how many genes affect it, and the type of
dominance.
 1 gene “R” and “r”
 Complete dominance = Red flowers and white flowers
 Codominnce = Red and white spotted flowers
 Incomplete dominance = Red flowers, pink flowers, and
white flowers
Phenotypic Variation
Pheotype variation: traits have a variety of “looks”
 Polygenic characters are influenced by several genes.
Examples include human eye color and height.
 Study by measuring each individual and then analyzing
the distribution.
Phenotype Variation
 Examples
Phenotypic Variation
 A distribution is an overview of the relative frequency and
range of a set of values.
 A normal distribution, or bell curve, is one that tends to
cluster around an average value in the center of the
range.
Genotype Frequencies Vs.
Allele Frequencies
Sources of Genetic
Variation
Evolution cannot proceed with no variation. The major
source of new alleles is mutation in germ cells.
 New alleles appear slowly.
 Only mutations in egg and sperm are passed on to
offspring.
Mutation Brainstorm
Put these in your notebook.
1. Give an example of a beneficial and a harmful mutation.
2. Discuss how the two mutations would most likely be
affected by natural selection.
2/8 Bell Work
Shadow drove into the Speedy Service Station and pulled up
to the pumps. “Fill it up please,” said Shadow. “This may
sound strange,” said the owner, “but I’d rather fill up two cars
from out of town than one car from this town.” Shadow
looked at the man and replied, “I know just what you mean.”
 Why does his statement make sense, economically
speaking?
2/8 Schedule
 Notes Ch 17.2 “Genetic Change”
 QL: Alleles the Next Generation
 Work
 Missing assignments
 Dir Rdg Ch 17 due TBA
Assignments:
1. Dir Rdg Ch 16 “Evolution” LATE
2. Grade Reports and Letter Home LATE
3. Natural Selection Simulation due TODAY
4. Natural Selection Wksht due TODAY
Ch 17.2 “Genetic
Change”
Objectives
1. Describe the the Hardy-Weinberg principle.
2. Explain how sexual reproduction effects evolution.
3. Identify the importance of population size on survival.
4. Describe the limits and patterns of natural selection.
Equilibrium and Change
Stability vs Change
 Genetic equilibrium: no genetic change
 Changes can be measured in genotype or allele
frequency
Equilibrium
Equilibrium
Change
Equilibrium and Change
Hardy-Weinberg Principle
 Predicts frequencies of alleles and genotypes will not
change unless at least one of five forces acts.





gene flow
nonrandom mating
genetic drift
mutation
natural selection
Equilibrium and Change,
continued
Gene Flow
 Gene flow occurs when genes are added
to or removed from a population.
 Can be caused by migration.
Nonrandom Mating
 Limits or preferences of mates
Equilibrium and Change,
continued
Genetic Drift
 Chance events can cause rare alleles to be lost, especially
when populations are small.
Mutation
 Mutation can add a new allele to a population.
Equilibrium and Change,
continued
Natural Selection
 Natural selection acts to eliminate individuals with certain
traits and their alleles become less common.
Sexual Reproduction and
Evolution
Benefits of Sexual Reproduction in Evolution
 Creates chances to recombine alleles and increase
variation.
 Mating patterns or behaviors can influence the gene pool.
 Females sometimes select mates based on the male’s size, color,
ability to gather food, etc.
birds of paradise
Sexual Reproduction and
Evolution
Influencing the Gene Pool
 Inbreeding: individuals either self-fertilize or mate with
others like themselves.
 Inbreeding is more likely if a population is small because
all members are likely to be closely related.
European royal families often
suffer from hemophilia.
Poodles are prone to seizures.
Population Size and
Evolution
Population Size
 Strongly affects the probability of genetic change.
 Allele frequencies are more likely to remain stable in
large populations than small.
QL: Alleles the Next
Generation
 Collect class data, lab sheet as desk groups.
 Everyone gets 2 blocks.
 Purple (P) is dominant to white (p)
 Without looking, pass one of your blocks to someone else
every generation. RANDOM “MATING”!
 Keep track of genotypes and phenotypes for 5 generations.
 Answer questions and keep for tomorrow.
Natural Selection and
Evolution
How Selection Acts
 Natural selection causes evolution by acting on individual
survival.
 Less “fit” individuals are less likely to pass on their
genes.
Natural Selection and
Evolution
Results of Selection
 The result of natural selection is that each allele’s
frequency may increase or decrease depending on the
effects on survival and reproduction.
 The ENVIRONMENT does the selection.
2/9 Bell Work
Draw 4 rectangles. Put 9 X’s in the four rectangles so that
there is an odd number of X’s in each.
 How is this possible?
X
X
X
X
X
X
X
X
X
 Hint: Can overlap rectangles
2/9 Schedule
 Notes Ch 17.2 “Genetic Change”
 QL: Genetic Risk and Hardy-Weinberg Problems
 Work
 Missing assignments
 Dir Rdg Ch 17 due TBA
Assignments:
1. Natural Selection Simulation LATE
2. Natural Selection Wksht LATE
3. Hardy-Weinberg Wksht due THURSDAY
Natural Selection and
Evolution
Natural selection is indirect
 It acts only to change the relative frequency of alleles that
exist in a population.
 It acts on genotypes by removing unsuccessful phenotypes
from a population.
Hardy-Weinberg Equation
The H-W Equation can predict frequency of alleles and
genotypes.
 Allele Frequency: p + q = 1
 Genotype Frequency:
Hardy-Weinberg Equation
Albinism is a rare homozygous recessive trait.(aa). The
characteristic symptom is a lack of pigment. The average human
frequency of albinism in North America is only about 1 in 20,000.
 The frequency of homozygous recessive individuals (aa) in a
population is q². Therefore the allele frequency is…
 q² = 1/20,000 = .00005
 q = .007 or 1 in 140 people
 Therefore the dominant allele frequency is…
 p=1–q

p = 1 - .007 p = .993
2/10 Bell Work
“Mr. Shady?” inquired Shadow. “I’m afraid I have some
some bad news. Your brother-in-law’s been murdered.”
“Oh no!” replied Shady. “I just saw Sam. I’m not surprised
though, he had a lot of enemies. He just got in fight with all
my sisters’ husbands over a business deal, and he owes
people a lot of money. Then there’s my sister’s brother who
just got out of jail who’d accused Sam of framing him…”
 As Shady rambled, Shadow arrested him on suspicion of
murder. Why?
2/10 Schedule
 Notes Ch 17.2 “Genetic Change”- Ch 17.3 “Speciation”
 Start Genetic Drift Lab
 Work
 Missing assignments
 Dir Rdg Ch 17 due FRIDAY
Assignments:
1. Natural Selection Simulation LATE
2. Natural Selection Wksht LATE
3. Hardy-Weinberg Wksht due THURSDAY
4. Dir Rdg Ch 17 due FRIDAY
Hardy-Weinberg Practice
Rabbits can be brown or white which is recessive. The
frequency of the BB genotype is .35.
 What is the frequency of the B allele?
 What are the chances any individual rabbit is
heterozygous?
Patterns of Natural
Selection
Three major patterns affect the distribution of polygenic
characters over time.
 These patterns are:
 directional selection
 stabilizing selection
 disruptive selection
Patterns of Natural
Selection, continued
Directional Selection
 In directional selection, the “peak” of a normal
distribution moves in one direction along its range.
 Eliminated one extreme phenotype, making them less
common.
Patterns of Natural
Selection, continued
Stabilizing Selection
 In stabilizing selection, the bell-curve shape becomes
narrower. Both extreme phenotypes eliminated.
 Not very common in nature.
Patterns of Natural
Selection, continued
Disruptive Selection
 In disruptive selection, the bell curve is “disrupted” and
pushed apart into two peaks.
 Average phenotype eliminated.
Kinds of Selection
Ch 17.3 “Speciation”
Objectives
 Define species and speciation.
 Explain why studying extinction is important in
understanding evolution.
Species?
Describe differences that let you distinguish between dogs
and cats.
Defining Species
Multiple Definitions for Species
1. Species: group of natural populations that can
interbreed and usually produce fertile offspring
 based on the biological species concept.
Defining Species
Multiple Definitions for Species
 Other definitions may be used for fossils or asexual
organisms.
 Useful characteristics:
 physical features
 ecological roles
 genetic relatedness.
Forming New Species
Divergence
 Each population of a species lives in a different place.
 Offspring that are adapted to each.
 Eventually can lead to the formation of new subspecies
and then species.
Forming New Species,
continued
Speciation: forming new species by evolution from
preexisting.
 Evolutionary forces result in a population that has
unique features and is reproductively isolated.
 Reproductive isolation: two populations can no longer
interbreed to produce future offspring.
Genetic Drift Lab
How does population size affect the alleles?
 Use populations of 5, 10, and 20… how many alleles
from each “person”? ________________
 Model 4 generations in each population group.
 Generation 2-4 use the “gene pool” ratios from the
generation before.
Roles
1st = On task
2nd = Hands on
3rd = Secretary
2/11 Bell Work
Rearrange the letters in the words below to discover what they
detect.
the detectives
2/11 Schedule
 Notes Ch 17.3 “Speciation”
 Genetic Drift Lab – Finish Pop 10 TODAY
 Work
 Missing assignments
 Dir Rdg Ch 17 due FRIDAY
Assignments:
1. Natural Selection Simulation LATE
2. Natural Selection Wksht LATE
3. Hardy-Weinberg Wksht due TODAY
4. Dir Rdg Ch 17 due FRIDAY
Forming New Species,
continued
Mechanisms of Isolation
 Any of the following mechanisms may contribute to the
reproductive isolation of populations:
 Geography
 Ecological Niche
 Mating Behavior and Timing
 Polyploidy
 Hybridization
Red wolves are grey wolf-coyote
hybrids.
Extinction: The End of
Species
Extinction: a species fails to produce any more descendants.
 More than 99% of all of the species that have ever lived
become extinct.
1. Tasmanian wolf
2. Dodo bird
3. Yangtze River
Dolphin
Extinction: The End of
Species
 Many cases of extinction are the result of environmental
change.
 If a species cannot adapt fast enough to changes, the
species may be driven to extinction.
2/12 Bell Work
Heigh ho, it’s off to school you go…Disney released its first
full-length animated film in 1938.
 Name the film.
2/12 Schedule
 “Spell of the Albino”
 Genetic Drift Lab – Finish data today, due TUESDAY
 Work
 Missing assignments
 Dir Rdg Ch 17 due TODAY
Assignments:
1. Natural Selection Simulation LATE
2. Natural Selection Wksht LATE
3. Hardy-Weinberg Wksht LATE
4. Dir Rdg Ch 17 due TODAY
“Spell of the Albino”
 What are albinos?
 Have you ever seen any? Where?
 Albinos are relatively rare in nature. Why do you think this
is?
 Do you think culture selects for certain groups of people and
against others? How? Why? Think “beauty”…
2/17 Bell Work
Scheming Suzie is trying to get out of going to school
because she “just doesn’t have time for classes”. Her
reasoning is below…
What is the flaw in her
argument?
Activity
Days
Sleep (8 hrs/day)
122
Weekends
104
Eating (3 hrs/day)
45
Summer vacation
60
“Fun” (2 hrs/day)
30
TOTAL
361
2/17 Schedule
 Rat Island Work Day 2/2
 Questions? Problems yesterday?
 Due THURSDAY
 Work
 Missing assignments
Assignments:
1. Natural Selection Wksht LATE
2. Hardy-Weinberg Wksht LATE
3. Dir Rdg Ch 17 LATE
4. Genetic Drift Lab LATE
Ch 16-17 Test THURS-FRI
depending on schedule
Rat Island Project
 2 days in class to create a “comic book” for 6-10 year olds
AND do Hardy-Weinberg #2. DUE END OF CLASS
2/13!!
 Work in partners or by yourself.
 Follow the checklist…these are things you will be graded on!
 Draw a block from the pouch to determine your island.
Block
Island
White
A
Black
B
Blue
C
Yellow D
2/13 Schedule
 Finish Rat Island AND Hardy-Weinberg #2
Rat Island Project
 DUE END OF CLASS 2/13: “comic book” for 6-10 year
olds AND do Hardy-Weinberg #2.
 Follow the checklist…these are things you will be graded on!
Block
Island
White
A
Black
B
Blue
C
Yellow D
Adaptation Overview
 Variation - The naturally-occurring differences among
individuals in a species.
 Adaptations - naturally-occurring (and usually
genetically controlled) differences that give some
individuals advantages in their particular environment.
 The organisms with Adaptations are more likely to be
Naturally Selected and pass on their genes.