Transcript 16 & 17-Patterns of Evolution

PATTERNS OF EVOLUTION
Chapter 16 & 17
http://www.baystatereplicas.com/images/repro_dino_pecksrex3.jpg
POLYGENIC
_______________
traits are
controlled by two or
more genes.
A bell shaped curve is
typical of polygenic traits
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
The ___________
FITNESS of individuals near
each other will not be very different, but
fitness may vary from one end of curve
to the other.
Where fitness varies,
NATURAL SELECTION
________________
can act!
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
Natural selection can affect the
distribution of phenotypes in 3 ways:
______________________
DIRECTIONAL selection
STABILIZING selection
______________________
DISRUPTIVE selection
______________________
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
• DIRECTIONAL SELECTION
KEY
Low mortality,
high fitness
Food becomes scarce.
High mortality,
low fitness
Individuals at _____________
ONE END of the curve
have higher fitness than individuals in
middle or at other end.
Graph shifts as some individuals fail to survive at one end
and succeed and reproduce at other
EXAMPLE OF DIRECTIONAL SELECTION
Beak size varies in a population
Birds with bigger beaks can feed
more easily on harder, thicker
shelled seeds.
Suppose a food shortage causes
small and medium size seeds to
run low.
Birds with bigger beaks would be
selected for and increase in numbers
in population.
http://www.animalbehavior.org/ABS/Stars/ONI/Podos_-_finch_graphic.jpg
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
• STABILIZING SELECTION
Individuals in _____________
CENTER of the curve
have higher fitness than individuals at
either end
Graph stays in same place but narrows as more organisms
in middle are produced.
STABILIZING SELECTION
Section 16-2
Male birds use
their plumage to
attract mates.
Male birds in the
population with
less brilliant and
showy plumage
are less likely to
attract a mate,
while male birds
with showy
plumage are more
likely to attract a
mate.
Stabilizing Selection
Key
Low mortality,
high fitness
High mortality,
low fitness
Selection
against both
extremes keep
curve narrow
and in same
place.
Male birds with
showier, brightlycolored plumage
also attract
predators, and are
less likely to live
long enough to
find a mate.
The most
fit, then, is the male
bird in the middle-showy, but not too
showy.
Brightness of
Feather Color
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
EXAMPLE OF STABILIZING SELECTION
Human babies born with low birth
weight are less likely to survive.
Babies born too large have difficulty
being born.
Average size babies are selected for.
http://www.animalbehavior.org/ABS/Stars/ONI/Podos_-_finch_graphic.jpg
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
• DISRUPTIVE SELECTION
EXTREMES of the curve
Individuals at _____________
have higher fitness than individuals in middle.
Can cause graph to split into two.
TWO DISTINCT
Selection creates __________________PHENOTYPES
EXAMPLE OF DISRUPTIVE SELECTION
Suppose bird population lives in area
where climate change causes medium
size seeds become scarce while large
and small seeds are still plentiful.
Birds with bigger or smaller beaks
would have greater fitness and the
population may split into TWO
GROUPS. One that eats small
seeds and one that eats large seeds.
http://www.animalbehavior.org/ABS/Stars/ONI/Podos_-_finch_graphic.jpg
Large scale evolutionary patterns and processes
that occur over long periods of time =
Macroevolution
________________________
1.
2.
3.
4.
5.
_______________________
Mass extinction
Adaptive radiation (Divergent_evolution)
_______________________
Convergent evolution
________________________
Coevolution
________________________
Punctuated equilibrium
________________________
Mass Extinctions
At several times in Earth’s history large numbers
of species became extinct at the same time
Caused by several factors:
• erupting volcanoes
• Plate tectonics (continents were moving)
• Changing sea levels
• Asteroids hitting the Earth
The 6th Extinction
• Global climate change
Example:
At the end of the _________________
MESOZOIC Eramore than HALF of all plants and animals
were wiped out… including the dinosaurs
http://www.changbi.com/file_img/webzine/dinosaur02_02.jpg
Effects of mass extinctions:
Opens
habitats and provides opportunities
_____________
for ______________species
remaining
After mass extinctions there is often a
___________________
burst of evolution that produces many
__________________
new species
EX: Cenozoic era that followed
= “_______________”
Age of Mammals
Mammals species
increased dramatically
Image from: BIOLOGY by Miller and Levine; Prentice Hall Publishing©2006
When a single species or small group of
species has evolved through
___________________
natural selection into diverse forms
that live in different ways =
____________________________________
adaptive
radiation OR divergent evolution
Ex:
Galápagos finches
More than a dozen species evolved from one species
http://www.pbs.org/wgbh/evolution/library/01/6/image_pop/l_016_02.htm
Sometimes different organisms
evolution in different places or at
different times but in
_________________________
ecologically similar
environments…and end up looking
very similar.
Process by which unrelated
organisms come to resemble each
other = _______________________
convergent evolution
Example:
Sharks, penguins,
dolphins have all
developed
________________
streamlined
bodies
and appendages to
move
through water.
http://www.painetworks.com/photos/ii/ii1971.JPG
The process by which two
species evolve in response
to changes in each other
over time
= __________________
coevolution
Bozeman Biology Coevolution
http://biology.clc.uc.edu/courses/bio303/coevolution.htm
How fast does evolution operate?
Darwin believed evolution
happened slowly over a
long time
If biological change is
at a slow pace, it is
called
_____________.
gradualism
http://animals.timduru.org/dirlist/dino/FlyingDinosaurus-Pterodon-fossil.jpg
Fossil record shows evolution
happens more inbursts
_____.
Pattern of a long stable period
interrupted by a brief
period of more
rapid change
Punctuated
=____________
Equilibrium
Rapid evolution after long periods of equilibrium
can occur for several reasons:
1) Happens when a small population is
____________
ISOLATED from the main population OR
2) A small group ________________to
a new
MIGRATES
environment (like Galápagos finches)
http://www.pbs.org/wgbh/evolution/library/01/6/image_pop/l_016_02.html
http://tolweb.org/tree/ToLimages/blank_map.250a.gif
ARE THERE ANY CONDITIONS IN
WHICH EVOLUTION WILL NOT
OCCUR?
IS THERE A WAY TO TELL IF THIS IS
HAPPENING?
HARDY-WEINBERG
PRINCIPLE
__________________________
Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006
Hardy & Weinberg
Who?
Godfrey Hardy
1877-1947
Wilhelm Weinberg
1862-1937
They developed an equation that predicted the relative
frequency of alleles in a population based on the frequency
of the phenotypes in a population.
Gene Frequency & the
Hardy-Weinberg Equation
The Hardy-Weinberg Equation
p2 + 2pq + q2 = 1
p2 = the frequency of homozygous dominant genotype
2pq = the frequency of heterozygous genotype
q2 = the frequency of homozygous recessive genotype
HARDY-WEINBERG PRINCIPLE
= allele frequency in a population
will remain __________
constant unless one
factors cause the
or more ________
frequency to __________.
change
In a situation in which allele
frequencies remain constant
( = Genetic
_________________
equilibrium )
populations will NOT EVOLVE!
5 CONDITIONS REQUIRED TO
MAINTAIN GENETIC EQUILIBRIUM
FROM GENERATION TO GENERATION
Random mating
1. _________________________
Large population
2. _________________________
movement in or out
3. No
_________________________
No mutations
4. _________________________
No natural selection
5. _________________________
RANDOM MATING
= ____________of
ALL members the population must
have an equal opportunity to produce
offspring
If some organisms are more likely to
reproduce than others, the alleles in the
population change.
http://ideiasemdesalinho.blogs.sapo.pt/arquivo/Peacock%20with%20its%20tail%20fanned%20out_Tony%20Ruta.jpg
http://www.wasatchcomputers.net/gallery/elk_fight.jpg
LARGE POPULATIONS
In small populations, changes can
chance instead of
happen due to _________
natural selection.
http://evolution.berkeley.edu/evosite/evo101/IIIDGeneticdrift.shtml
NO MOVEMENT IN OR OUT
Organisms take their alleles with them
where ever they go.
http://evolution.berkeley.edu/evosite/evo101/IIIC4Geneflow.shtml
NO MUTATION
Mutations add new alleles to gene pool.
http://evolution.berkeley.edu/evosite/evo101/VADefiningSpecies.shtml
NO NATURAL SELECTION
If some organisms are more likely to
survive than others, the alleles in the
population change.
Evolution vs. Genetic
Equilibrium
In some populations,
these
conditions
may be met or nearly met over long
periods of time, and little or no
________
evolution occurs.
difficult
BUT in most populations it is _______
for ____
ALL conditions of Hardy-Weinberg
to be met.
In MOST populations . . .
EVOLUTION happens !
http://www.educa.rcanaria.es/fundoro/00.corsi.htm
LATEST DISCOVERIES IN SCIENCE:
WAS LAMARCK RIGHT AFTER ALL?
Can ACQUIRED TRAITS be inherited?
?
http://www.geocities.com/arnold_schwarzenegger_pictures
REMEMBER: EPIGENETICS
Prader-Willi syndromeBorn floppy and pale; Mildly retarded;
Obesity;Tiny hands and feet; Short stature
Underdeveloped sex organs,
Spectacular temper tantrums especially if
refused food
Angelman syndrome spontaneous laughter, jerky movements,
severe retardation; and other motor and
mental symptoms.
Both missing same piece of chromosome #15
Prader- Willi- paternal piece missing
Angelman – maternal piece missing
Difference is due to genomic imprinting
http://www.angelman.org/angel/
GENOMIC IMPRINTING
Addition or removal or “methyl tags” may be
influenced by environment
• Twins start with same methyl tags but become
more different with age
• Agouti rats – changing diet of pregnant mom can
change expression of genes
VIDEO
http://www.precisionnutrition.com/wordpress/wp-content/uploads/2009/12/Figure-3-Agouti-mice.jpg
SO WHAT?
• If things you do can change the way your genes
are expressed , then …..
maybe you can inherit some acquired traits!
• Can your choices affect your kids’ and grandkids’
epigenome?
http://www.naturepedic.com/blog/wp-content/uploads/2010/11/BPA_free_logo.jpg
http://www.knowabouthealth.com/wp-content/uploads/2010/06/mcdonalds_.jpg
http://emilyscarenhealth.wordpress.com/2011/10/04/attention-a-must-read-for-smokers/
Chapter 16 – Evolution of Populations:
The students will be able to:
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•
•
•
•
•
•
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Explain Darwin’s observations of population variation
Compare contributions of scientists to our understanding of a changing population
(9-12.S.1.2)
Predict the results of complex inheritance patterns involving multiple alleles and genes
(9-12.L.2.1A)
Predict inheritance patterns using a single allele (9-12.L.2.1)
Evaluate changes in gene frequencies in populations to determine if Hardy-Weinberg
equilibrium exists or evolution has occurred (9-12.L.2.1A.)
Describe how genetic recombination, mutations, and natural selection lead to
adaptations, evolution, extinction, or emergence of new species (9-12.L.2.2)
(Directional, stabilizing, disruptive selection, Genetic drift, Founder effect)
Use comparative anatomy to support evolutionary relationships (9-12.L.2.2)
(homologous structures, embryology)
Predict the impact of genetic changes in populations (9-12.L.2.2)
(mutation, natural selection, artificial selection, gene shuffling)
Predict the results of complex inheritance patterns involving multiple alleles and genes
(9-12.L.2.2) (SYNTHESIS)
LIFE SCIENCE:
Indicator 2: Analyze various patterns and products
of natural and induced biological change
• 9-12.L.2.2. Students are able to describe how genetic
recombination, mutations, and natural selection lead to
adaptations, evolution, extinction, or the emergence of new
species.
• Examples:
•
behavioral adaptations, environmental pressures, allele
variations, bio-diversity
• Use comparative anatomy to support evolutionary relationships.
LIFE SCIENCE:
Indicator 3: Analyze how organisms are
linked to one another and the environment.
• 9-12.L.3.1. Students are able to identify factors that
can cause changes in stability of populations,
communities, and ecosystems.
• Predict the results of biotic and abiotic interactions.
• Examples:
Tolerances (temperature, weather, climate)
Migration
Fluctuation in available resources (water, food, shelter)
Cooperation and competition in ecosystems
SOUTH DAKOTA ADVANCED STANDARDS
LIFE SCIENCE
Indicator 2: Analyze various patterns and products of
natural and induced biological change.
• 9-12.L.2.1A. Students are able to predict the results of complex
inheritance patterns involving multiple alleles and genes.
• Examples: human skin color, polygenic inheritance
• Relate crossing over to genetic variation.
• Evaluate changes in gene frequencies in populations to see if
HardyWeinberg equilibrium exists or evolution has occurred.
SOUTH DAKOTA
CORE SCIENCE STANDARDS
LIFE SCIENCE:
Indicator 2: Analyze various patterns and products
of natural and induced biological change.
9-12.L.2.2. Students are able to describe how
genetic recombination, mutations, and natural
selection lead to adaptations, evolution,
extinction, or the emergence of new species.
(SYNTHESIS)
Core High School Life Science
Performance Descriptors
High school students
performing at the
ADVANCED level:
predict how traits are transmitted from parents to
offspring;
High school students
performing at the
PROFICIENT level:
predict the impact of genetic changes in populations
(mutation, natural selection and artificial selection,
adaptation/extinction);
predict how life systems respond to changes in the
environment;;
High school students
performing at the
BASIC level
identify DNA as the structure that carries the genetic
code;
identify that genetic traits can be transmitted from
parents to offspring;