Download Chapter 13-16 Evolution Teacher notes

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 13
How Populations Evolve
Modules 13.1 – 13.3
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
EVIDENCE OF EVOLUTION
Introduction to Evolution
• Aristotle and the Judeo-Christian culture
believed that species are fixed
• Fossils suggested that life forms change
– This idea was embraced by Lamarck in the early
1800s
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Early Ideas about Evolution
• Spontaneous Generation: idea that living
things could arise from nonliving things. Also
known as abiogenesis.
– Examples: eels and frogs “arising” from mud,
fleas and lice “arise” from sweat, mice “arose”
from garbage
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“Examples” of abiogenesis
• Jan Baptista van Helmont: places wheat grains
in a sweaty shirt, after 21 days the wheat is
gone and mice are present
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Disproving abiogenesis
• Francesco Redi: Experimented with meat and
maggots. Noticed that flies appeared around
decaying meat. Designed an experiment to
show that maggots do not “arise”
spontaneously from decaying meat.
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More “examples” of abiogenesis
• John Needham: boiled flasks of chicken, lamb
and corn broth for a few minutes to kill any
microorganisms then sealed flasks. After
several days opened flasks and found them
“teeming” with microorganisms.
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Disproving abiogenesis (again)
• Lorenzo Spallanzani: claimed Needham didn’t
boil the flasks long enough to kill all the
organisms originally present. Repeats
Needham’s experiment, but boils them much
longer.
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And the reply
• Needham argues that Spellanzani heated the
flasks so long that he destroyed the “vital
principle” in the air that was necessary to bring
about the generation of new organisms. (100
year debate about this)
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Finally disproving abiogenesis
• Louis Pasteur: French chemist, thought
microorganisms and their spores were present
in air and they became active when they
entered broth. His experiments and his
apparatus finally disprove abiogenesis
(spontaneous generation)
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• Jean Baptiste Lamarck
Figure 13.1x4
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• Lamarck was the first person to develop a
“Theory of Evolution”
• Had two parts to his evolutionary theory:
• Use and Disuse: If a body part was used it was
kept and became stronger and better
developed.
• Inheritance of Acquired Characteristics:
Characteristics/traits acquired during an
organisms lifetime could be passed onto their
children.
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Fig. 21.2a(TE Art)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
stretching
stretching
Proposed ancestor
of giraffes has
characteristics of
modern-day okapi.
Lamarck's theory: variation is acquired.
reproduction
August Weisman disproved Lamarck’s ideas
• Chopped off the tails of
mice and then bred them
together. All offspring
always had tails.
• This investigation
disproved Lamarck’s
Evolutionary “Theory”
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• Charles Darwin, 1859
Figure 13.1x1
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• The voyage of the Beagle
Great
Britain
Europe
North
America
Pacific
Ocean
Atlantic
Ocean
Africa
Galápagos
Islands
Equator
South
America
Australia
Cape of
Good Hope
Tasmania
Cape Horn
Tierra del Fuego
New
Zealand
Figure 13.1B
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• While on the voyage of the HMS Beagle in the
1830s, Charles Darwin observed
– Similarities between living and fossil organisms
– the diversity of life on the Galápagos Islands,
such as blue-footed boobies and giant tortoises
Figure 13.1A
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• Charles Lyell:
Wrote a book called
Principles of
Geology that talked
about gradualism,
slow constant
change over time,
and influenced
Darwin.
Figure 13.1x5
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Thomas Malthus
• Wrote an essay: On the
Principle of Population
• Said that the increase of
population is limited by
the means of subsistence
(resources)
• That population does
invariably increase
(exponentially) when the
means of subsistence
increase (more
arithmetically)
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More Thomas Malthus
• The growth of population is repressed, and
the actual population kept equal to the
means of subsistence, by misery and vice
• Influences Darwin’s view of the impact of
resources and the environment on the
potential for growth in a population.
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• Darwin also saw that
when humans choose
organisms with specific
characteristics as
breeding stock, they are
performing the role of the
environment
– This is called artificial
selection
– Example of artificial
selection in plants: five
vegetables derived from
wild mustard
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Figure 13.4A
– Example of artificial selection in animals: dog
breeding
German shepherd
Yorkshire terrier
English springer
spaniel
Mini-dachshund
Golden retriever
Hundreds to
thousands of years
of breeding
(artificial selection)
Ancestral dog
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Figure 13.4B
• These five canine species evolved from a
common ancestor through natural selection
African wild
dog
Coyote
Fox
Wolf
Jackal
Thousands to
millions of years
of natural selection
Ancestral canine
Figure 13.4C
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• Darwin became convinced that the Earth was
old and continually changing
– He concluded that living things also change, or
evolve over generations
– He also stated that living species descended
from earlier life-forms: descent with
modification
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• Darwin concluded that individuals best suited
for a particular environment are more likely to
survive and reproduce than those less well
adapted.
• Darwin saw natural selection as the basic
mechanism of evolution
– As a result, the proportion of individuals with
favorable characteristics increases
– Populations gradually change in response to the
environment
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• Darwin’s Evolutionary theory included the
ideas of:
• Overproduction: organisms produce more
offspring than the environment can support
• Competition: there aren’t enough resources for
all members of the population, so they all
compete with each other.
• Variation: organisms vary in many
characteristics, these variations can be
inherited
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• Adaptation: some variations provide organisms a
survival and reproductive advantage.
• Struggle for survival: organisms with the most
favorable adaptations are selected for in their
environment survive, reproduce and most likely
pass the adaptations on to their offspring.
Organisms without the adaptations are selected
against and may not survive (eliminates their
traits).
• Speciation: over time the population may become
a new species if enough new variations and
adaptations are accumulated.
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DARWIN’S THEORY AND THE MODERN
SYNTHESIS
Darwin proposed natural selection as the
mechanism of evolution
• Darwin’s and Mendel’s ideas were later combined into
what is now called the Modern Synthesis Theory. This
solved the two flaws in Darwin’s Theory:
• 1
Darwin couldn’t’ explain the source of variation. Today
we know that this is mutation.
(discovered by Hugo DeVries)
• 2
Darwin couldn’t’ explain how variations were passed
on from parent to offspring. This was explained by
Mendel’s investigations with pea plants.
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• Alfred Wallace:
worked in British
West Indies.
Performed
investigations and
came to conclusions
that were similar to
Darwin’s
Figure 13.1x6
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• The Origin of Species frontispiece
Figure 13.1x7
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• Charles Darwin, 1874
Figure 13.1x2
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Fig. 21.2b(TE Art)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
reproduction
reproduction
Some individuals
born happen to
have longer necks.
reproduction
Over many generations, longer-necked individuals
are more successful, perhaps because they can
feed on taller trees, and pass the long-neck trait
on to their offspring.
Darwin's theory: variation is inherited.
How do we know that evolution has taken place?
Many different examples of evolution exist. One of the best
of those examples are found in the fossil record.
Fossil: remains of a once living thing.
The study of fossils provides strong evidence for
evolution
• Fossils and the fossil record
strongly support the theory of
evolution
– Hominid skull
– Petrified trees
Petrifaction – process that petrifies
organisms. Die and fall in lakes with a
high mineral content. Minerals diffuse
into dead organism making them hard
as stone.
Figure 13.2A, B
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• Fossil perch
Figure 13.2x1
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• Barosaurus
Figure 13.2x3
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– Ammonite casts
– Fossilized organic
matter in a leaf
Figure 13.2C, D
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– Scorpion in amber
– Amber – tree sap
that is hardened
through time.
– “Ice Man”
– “frozen” organisms
Figure 13.2E, F
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• Mammoth tusks
Figure 13.2x4
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• The fossil record shows
that organisms have
appeared in a historical
sequence
• Most fossils are found in
sedimentary rock
• Many fossils link early
extinct species with
species living today
– These fossilized hind leg
bones link living whales
with their land-dwelling
ancestors
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Figure 13.2G, H
How can you tell if fossils and modern day
organisms are related?
• Comparative anatomy: look at anatomical
structures (skeleton).
– Look for homologous structures (homology):
these are body parts that have similar structure
and similar embryonic development, but may
have a slightly different function. Evidence of
common ancestry. (Divergent Evolution)
• Ex: human arm, bat wing, cat leg, whale flipper,
alligator leg, bird wing (see diagrams on next slide)
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A mass of evidence validates the evolutionary view
of life
• Other evidence for evolution comes from
– Biogeography
– Comparative
anatomy
– Comparative
embryology
Human
Cat
Whale
Bat
Figure 13.3A
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• May also look for analogous structures
(analogy): these are body parts that have the
same function, but a different structure and
embryological development. Organisms do
not have a recent common ancestor.
(Convergent Evolution)
– Ex: bird wing and insect wing
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Vestigial structures: something that used to serve
a purpose, but now does not.
ex: human appendix, wisdom teeth, hip bones
in whales.
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• Also look at:
• Comparative
embryology: look at
how the embryos of
different organisms
develop over time.
Similar development is
evidence that they
have a common
ancestor.
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• Comparative cytology: compare cell structures
• Comparative behavior: look at particular
behaviors and who performs what types of
behaviors.
• Comparative biochemistry: Look at the
molecular sequence of DNA, polypeptides and
RNA. Having a lot in common means that the
organisms being studied have a common
ancestor.
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– Molecular biology (comparative biochemistry)
Human
Rhesus monkey
Last common
ancestor lived
26 million years
ago (MYA),
based on
fossil evidence
Mouse
Chicken
Frog
Lamprey
80 MYA
275 MYA
330 MYA
450 MYA
Figure 13.3B
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Connection: Scientists can observe natural selection
in action
• Evolutionary Adaptations have been observed
in populations of birds, insects, and many other
organisms
– Example: camouflage adaptations of mantids
that live in different environments
Figure 13.5A
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• There are many different types of adaptations
that help animals. Examples include:
• Cryptic coloration (camouflage) helps the
organism “blend into” their environment. Can
be an advantage to either the prey OR the
predator.
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• Aposematic coloration (warning coloration):
organism produces a toxin (poison) and
“advertises” that it is poisonous with bright,
contrasting colors on their body. Ex: poison
dart frogs, monarch butterflies
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• Some organisms look like others that are
poisonous, this is known as mimicry. There are
two types of mimicry:
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• Batesian mimicry: where a nontoxic species
resembles a toxic one. Ex monarch and viceroy
butterflies, coral and king snakes.
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• Mullerian mimicry:
where two toxic
species resemble one
another. Ex
swallowtail
butterflies.
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• The evolution of insecticide resistance is an
example of natural selection in action. Gene for
insecticide/pesticide resistance is ALREADY in the
population.
Insecticide
application
Chromosome with gene
conferring resistance
to insecticide
Additional
applications of the
same insecticide will
be less effective, and
the frequency of
resistant insects in
the population
will grow
Survivor
Figure 13.5B
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Other examples of evolution
• Peppered Moth (industrial
melanism)
• Prior to industrialization in England
the light colored moth was the
predominant phenotype and the
trees were lighter in color due to the
presence of lichen (organism on the
bark).
• Dark colored moth found less
frequently (preyed upon more often,
more easily seen by predators).
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Peppered Moth continued …..
• After industrialization in England the
dark colored moth was the
predominant phenotype and the trees
were darker in color due to the
presence of pollution in the air
(pollution from machinery).
• Light colored moth found less
frequently (preyed upon more often,
more easily seen by predators).
• Idea of Industrial Melanism originally
proposed by H.B.D. Kettelwell.
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Populations are the units of evolution
• A species is a group of populations whose
individuals can interbreed and produce fertile
offspring
– Human populations tend
to concentrate locally, as
this satellite photograph
of North America shows
• The modern synthesis
connects Darwin’s theory
of natural selection with
population genetics
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Figure 13.6
Microevolution is change in a population’s gene
pool over time
• A gene pool is the total collection of genes in a
population at any one time
• Microevolution is a change in the relative
frequencies of alleles in a gene pool
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The gene pool of a nonevolving population remains
constant over the generations
• Hardy-Weinberg equilibrium
states that the shuffling of
genes during sexual
reproduction does not alter
the proportions of different
alleles in a gene pool
– To test this, let’s look at an
imaginary, nonevolving
population of blue-footed
boobies
Webbing
No webbing
Figure 13.8A
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• In most cases each gene contains two alleles. A
dominant allele and a recessive allele for each
gene.
• Use p for the frequency of the dominant allele
• Use q for the frequency of the recessive allele
• Frequency = how often something appears in a
population (gene pool)
• Frequency of the dominant allele + frequency of
the recessive allele = 1
• In other words p + q = 1
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• How many ways can allele combinations be
inherited? 3
• Homozygous dominant = pp, or p2
• Heterozygous = pq, or qp = 2pq
• Homozygous recessive = qq, or q2
• Therefore: p2 + 2pq + q2 = 1
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• Most of the time, you’re looking for the perfect
square in Hardy-Weinberg problems. Be careful
where you start.
• In a population of fuzzy bunnies, brow fur is
dominant over white fur. If the population is 64%
brown determine the frequency of both the
dominant and recessive alleles as well as all the
genotype frequencies for this population.
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• We can follow alleles in a population to observe
if Hardy-Weinberg equilibrium exists
Phenotypes
Genotypes
WW
Ww
ww
Number of animals
(total = 500)
320
160
20
Genotype frequencies
320/
500
= 0.64
Number of alleles
in gene pool
(total = 1,000)
640 W
Allele frequencies
800/
1,000
160/
500
20/
= 0.32
160 W + 160 w
= 0.8 W
200/
1,000
500
= 0.04
40 w
= 0.2 w
Figure 13.8B
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Recombination
of alleles from
parent generation
SPERM
EGGS
WW
p2 = 0.64
WW
qp = 0.16
Ww
pq = 0.16
ww
q2 = 0.04
Next generation:
Genotype frequencies
0.64 WW
Allele frequencies
0.32 Ww
0.8 W
0.04 ww
0.2 w
Figure 13.8C
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Connection: The Hardy-Weinberg equation is
useful in public health science
• Public health scientists use the Hardy-Weinberg
equation to estimate frequencies of diseasecausing alleles in the human population
– Example: phenylketonuria (PKU)
Ex: if 16% of the population in Rhode Island are
affected each year by cystic fibrosis, how many of
the people living in that state are expected to be
carriers of the disease?
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Five conditions are required for Hardy-Weinberg
equilibrium
• The population is very large
• The population is isolated
• Mutations do not alter the gene pool
• Mating is random
• All individuals are equal in reproductive success
• If ALL 5 Hardy-Weinberg conditions are met
(satisfied) it is possible the population is NOT
evolving (stays the same)
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There are several potential causes of
microevolution
• Genetic drift is
a change in a
gene pool due
to chance
(decreases the
population size
randomly)
– Genetic drift
can cause the
bottleneck
effect
Original
population
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Bottlenecking
event
Surviving
population
Figure 13.11A
– or the founder effect
– Part of the population is separated from the
original group (usually on an island, founding
population)
Figure 13.11B, C
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• Gene flow can change a gene pool due to the
movement of genes into or out of a population
• Mutation changes alleles
• Natural selection leads to differential
reproductive success
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Adaptive change results when natural selection
upsets genetic equilibrium
• Natural selection results in the accumulation of
traits that adapt a population to its environment
– If the environment should change, natural
selection would favor traits adapted to the new
conditions
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VARIATION AND NATURAL SELECTION
Variation is extensive in most populations
• Phenotypic variation may be environmental or
genetic in origin
– But only genetic changes result in evolutionary
adaptation
Natural selection “picks and chooses” the
variations that are adaptive for the environment,
directly chooses the phenotype and indirectly
chooses the genotype.
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• Many populations exhibit polymorphism and
geographic variation
Figure 13.13
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Connection: Mutation and sexual recombination
generate variation
A1
Parents
A1
A2
A3
MEIOSIS
A1
A2
A3
Gametes
FERTILIZATION
Offspring,
with new
combinations
of alleles
A1
A2
A1
A3
and
Figure 13.14
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Overview: How natural selection affects variation
• Natural selection tends to reduce variability in
populations
– The diploid condition preserves variation by
“hiding” recessive alleles
– Balanced polymorphism may result from the
heterozygote advantage
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Connection: Endangered species often have
reduced variation
• Low genetic variability may reduce the capacity
of endangered species to survive as humans
continue to alter the environment
– Studies have shown that cheetah populations
exhibit extreme genetic uniformity
– Thus they may have a
reduced capacity to
adapt to environmental
challenges
Figure 13.17
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The perpetuation of genes defines evolutionary
fitness
• An individual’s Darwinian fitness is the
contribution it makes to the gene pool of the
next generation relative to the contribution
made by other individuals
• Production of fertile offspring is the only score
that counts in natural selection
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There are three general outcomes of natural
selection
Frequency of
individuals
Original
population
Phenotypes (fur color)
Original
population
Evolved
population
Stabilizing selection
Directional selection
Diversifying selection
Figure 13.19
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• Stabilizing selection “chooses” a particular trait
(phenotype) that becomes the most common
one in the new population (most successful)
the “peak” becomes more narrow
• Directional selection: the peak (distribution of
phenotypes) shifts, or moves in a particular
direction.
• Diversifying (destabilizing/disruptive)
selection: the peak “splits” to opposite ends,
the more “extreme” phenotypes are chosen.
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Sexual selection may produce sexual dimorphism
• Sexual selection leads to the evolution of
secondary sexual characteristics
– These may give individuals an advantage in
mating
Figure 13.20A, B
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• Male and female lions
Figure 13.20x
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Natural selection cannot fashion perfect organisms
• This is due to:
– historical constraints
– adaptive compromises
– chance events
– availability of variations
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Connection: The evolution of antibiotic resistance
in bacteria is a serious public health concern
• The excessive use of antibiotics is leading to the
evolution of antibiotic-resistant bacteria
– Example:
Mycobacterium
tuberculosis
Figure 13.22
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BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 14
The Origin of Species
Modules 14.1 – 14.2
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Evolution Underground
• Evolution has generally been thought of as a
very gradual process
– However, examples of rapid evolution have been
observed
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CONCEPTS OF SPECIES
What is a species?
• Linnaeus used physical appearance to identify
species when he developed the binomial system
of naming organisms
– This system established the basis for taxonomy
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• But appearance alone does not always define a
species
– Example: eastern and western meadowlarks
Figure 14.1A
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• Similarities between some species and variation
within a species can make defining species
difficult
– Humans exhibit extreme physical diversity
Figure 14.1B
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• The biological species concept defines a species
as
– a population or group of populations whose
members can interbreed and produce fertile
offspring
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• A ring species may illustrate the process of
speciation
1
OREGON
POPULATION
Sierra
Nevada
COASTAL
POPULATIONS
Yelloweyed
Yellowblotched
2
Gap in
ring
Monterey
INLAND
POPULATIONS
Largeblotched
3
Figure 14.1C
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Reproductive barriers keep species separate
• Prezygotic and
postzygotic
reproductive
barriers prevent
individuals of
different species
from
interbreeding
Table 14.2
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• Courtship ritual in blue-footed boobies is an
example of one kind of prezygotic barrier,
behavioral isolation
• Many plant species have
flower structures that
are adapted to specific
pollinators
– This is an example of
mechanical isolation,
another prezygotic
barrier
Figure 14.2A, B
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• Hybrid sterility is one type of postzygotic
barrier
– A horse and a
donkey may
produce a hybrid
offspring, a mule
– Mules are sterile
Figure 14.2C
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MECHANISMS OF SPECIATION
Geographic isolation can lead to speciation
• When a population is cut off from its parent stock, species
evolution may occur
– An isolated population may become genetically unique as its gene
pool is changed by natural selection, genetic drift, or mutation
– This is called allopatric speciation
– Populations were both feographically and reproductively isolated
from each other.
Figure 14.3
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Islands are living laboratories of speciation
• On the
Galápagos
Islands,
repeated
isolation and
adaptation
have resulted
in adaptive
radiation of
14 species of
Darwin’s
finches
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Figure 14.4A
• Adaptive radiation happens when part of a
population is separated from the original, usually
on a group of islands too far to travel back from
• Over time the population may change and form a
new species different from the one on the
mainland.
• If the new population moves to different islands
within the island group it is possible that each
island is different from the others and selects for
different traits and adaptations.
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• This would lead to the production of many
new species over time.
• Each new species was formed (radiated
from) the original one that made its way
onto the group of islands.
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• Adaptive radiation on an island chain
1
A
Species A
from mainland
2
B
B
3
B
C
B
4
C
C D
C
C
D
5
Figure 14.4B
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Convergent vs Divergent Evolution
• Convergent Evolution: organisms look similar
because they live in similar environments or
have similar roles in their environment and the
environment selects similar adaptations.
• Divergent Evolution: organisms evolved from a
common ancestor, accumulate different
variations (adaptations) over time and develop
into different species over time (adaptive
radiation)
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Convergent Evolution
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Convergent Evolution
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Divergent Evolution
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Divergent Evolution
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• Sympatric speciation by polyploidy was first
discovered by Dutch botanist Hugo de Vries in
the early 1900s
• Polyploid organisms have extra chromosome
sets 3n, 4n, or 5n due to nondisjunction.
Figure 14.5B
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Connection: Polyploid plants clothe and
feed us
• Many plants are polyploid
– They are the products of
hybridization
– The modern bread wheat
is an example
Figure 14.6A
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• The evolution
of wheat
AA
BB
Wild
Triticum
(14 chromosomes)
Triticum
monococcum
(14 chromosomes)
AB
Sterile hybrid
(14 chromosomes)
Meiotic error and
self-fertilization
AABB
DD
T. turgidum
EMMER WHEAT
(28 chromosomes)
T. tauschii
(wild)
(14 chromosomes)
ABD
Sterile hybrid
Meiotic error and
self-fertilization
AA BB DD
T. aestivum
BREAD WHEAT
(42 chromosomes)
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Figure 14.6B
The tempo of speciation can appear steady or
jumpy
• According to the
gradualist model of the
origin of species
– new species evolve by
the gradual
accumulation of
changes brought about
by natural selection
• However, few gradual
transitions are found in
the fossil record
Figure 14.8A
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• The punctuated
equilibrium model
suggests that speciation
occurs in spurts
– Rapid change occurs
when an isolated
population diverges
from the ancestral
stock
– Virtually no change
occurs for the rest of
the species’ existence
Figure 14.8B
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BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 15
Tracing Evolutionary History
Modules 15.1 – 15.5
From PowerPoint® Lectures for Biology: Concepts & Connections
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Are Birds Really Dinosaurs with Feathers?
• Did birds evolve from dinosaurs?
• Evolutionary biologists investigate this question
by looking at the fossil record
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• The fossil of the earliest
known bird,
Archeaopteryx,
was discovered in 1861
• Fossils of
dinosaurs with
feathers may
support the birddinosaur theory
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EARTH HISTORY AND MACROEVOLUTION
The fossil record chronicles macroevolution
• Macroevolution consists of the major changes
in the history of life
– The fossil record chronicles these changes,
which have helped to devise the geologic time
scale
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Figure 15.1
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The actual ages of rocks and fossils mark geologic
time
• The sequence of fossils in rock strata indicates
the relative ages of different species
• Radiometric dating can gauge the actual ages of
fossils
• Uses radioactive isotopes and ½ lives to
calculate the age of a fossil or rock layer.
• Typical radioactive isotopes include Carbon 14
(5,730 years) and Uranium 238 (4.5 billion
years),
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Continental drift has played a major role in
macroevolution
• Continental drift is the slow, incessant
movement of Earth’s crustal plates on the hot
mantle
Eurasian
Plate
North
American
Plate
African
Plate
Pacific
Plate
Nazca
Plate
South
American
Plate
Split
developing
Indo-Australian
Plate
Antarctic Plate
Edge of one plate being pushed over edge of
neighboring plate (zones of violent geologic events)
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Figure 15.3A
• Plate boundaries and earthquake activity
Figure 15.3Ax
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India
South
America
MESOZOIC
Antarctica
PALEOZOIC
– Separation of
continents caused the
isolation and
diversification of
organisms
Eurasia
Africa
Millions of years ago
– Continental mergers
triggered extinctions
CENOZOIC
• This movement has
influenced the distribution
of organisms and greatly
affected the history of life
Laurasia
Figure 15.3B
• Continental drift explains the distribution of
lungfishes
– Lungfishes evolved when Pangaea was intact
Figure 15.3C
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NORTH
AMERICA
ASIA
EUROPE
AFRICA
SOUTH
AMERICA
AUSTRALIA
= Living lungfishes
= Fossilized lungfishes
Figure 15.3D
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Connection: Tectonic trauma imperils local life
• Plate tectonics, the movements of Earth’s
crustal plates, are also associated with
volcanoes and earthquakes
– California’s
San Andreas
fault is a
boundary
between two
crustal plates
San Andreas fault
San Francisco
Santa Cruz
Los Angeles
Figure 15.4A
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• San Andreas fault
Figure 15.4Ax
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• By forming new islands, volcanoes can create
opportunities for organisms
– Example: Galápagos
• But volcanic activity can also destroy life
– Example: Krakatau
Figure 15.4B, C
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Key adaptations may enable species to proliferate
after mass extinctions
• Adaptations that have evolved in one
environmental context may be able to perform
new functions when conditions change
– Example: Plant
species with
catch basins, an
adaptation to dry
environments
Figure 15.6
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“Evo-devo:” Genes that control development play a
major role in evolution
• “Evo-devo” is a field that combines evolutionary
and developmental biology
• Major adaptations may arise rapidly if
mutations occur in genes that control an
organism’s early development
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Evolutionary trends do not mean that evolution is
directed toward a goal
• Evolutionary trends may reflect unequal
speciation or survival of species on a branching
evolutionary tree
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Figure 15.8
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Phylogenetic trees strive to represent evolutionary
history
• Phylogeny is the evolutionary history of a group
of organisms
• Branches on the phylogenetic tree that are
connected indicate that those species are
related to each other.
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Cactus
ground finch
Medium
ground finch
Large
ground finch
Small
Large cactus
ground finch ground finch
Small
tree finch
Vegetarian
finch
Medium
tree finch
Large
tree finch
Woodpecker
finch
Mangrove
finch
Green
Gray
warbler finch warbler finch
Sharp-beaked
ground finch
Seed
eaters
Cactus flower
eaters
Bud
eaters
Ground finches
Insect
eaters
Tree finches
Warbler finches
Common ancestor from
South America mainland
Figure 15.9
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BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 16
The Origin and Evolution
of Microbial Life:
Prokaryotes and Protists
Modules 16.1 – 16.6
From PowerPoint® Lectures for Biology: Concepts & Connections
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EARLY EARTH AND THE ORIGIN OF LIFE
Life began on a young Earth
• Planet Earth formed some 4.6 billion years ago
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• The early atmosphere probably contained H2O,
CO, CO2, N2,NH3 (Ammonia) and possibly some
CH4, but little or no O2
• Volcanic activity, lightning, and UV radiation
were intense, lots of energy available, possibly
lots of mutations.
Figure 16.1A
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• Fossilized prokaryotes date back 3.5 billion
years
Figure 16.1B, D
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How Ancient Bacteria Changed the World
• Biological and geologic history are closely
intertwined
• Fossilized mats of prokaryotes
2.5 billion years old mark a
time when photosynthetic
bacteria were producing O2
that made the atmosphere
aerobic
– These fossilized mats are
called stromatolites
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Earliest animals; diverse algae
Earliest multicellular eukaryotes?
Billions of years ago
• Life may have
developed from
nonliving
materials as early
as 3.9 billion
years ago
= 500 million years ago
Earliest eukaryotes
Accumulation of atmospheric
O2 from photosynthetic
cyanobacteria
Oldest known prokaryotic fossils
Origin of life?
Figure 16.1C
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Formation of Earth
How did life originate?
• Small organic molecules must have appeared
first
– This probably happened when inorganic
chemicals were energized by lightning or UV
radiation. High planet temperatures also helped
molecules to combine together.
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• The theory of how life formed and developed on our planet
is called the Heterotroph Hypothesis, was developed by A.
I. Oparin
• States that the inorganic materials found in early earth’s
atmosphere and waters were combined together by
lightening, radiation and high temperatures.
• Life probably began in the oceans, most likely near deep
ocean vents (warm)
• Oparin said that all of the energy available “allowed”
inorganic molecules to combine into organic compounds.
Over time these compounds grouped together and formed
early forms of cells called coacervates (heterotrophs and
anaerobes). The coacervates evolved into more advanced
forms of early cells called protobionts, which eventually
evolved into cells.
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• These early heterotrophs were anaerobic, consume food
and release carbon dioxide.
• Could have been a mutation that led to phototrophs
evolving. They would have used light, water and the carbon
dioxide to make glucose and oxygen gas.
• Could have been a mutation that led to aerobes evolving.
They would have used oxygen gas and glucose for food and
released water and carbon dioxide.
• Over time the UV radiation formed an ozone layer from the
oxygen gas and produced a protective layer around our
planed (ozone layer). Life would have continued to evolve
and develop through time.
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After the ozone layer forms - Endosymbiosis
Some cells evolved membrane-enclosed
compartments called organelles.
Example: The nucleus contains the genetic
information.
These cells are eukaryotes
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Endosymbiosis (continued)
Some organelles may have originated by
endosymbiosis, when larger cells engulfed
smaller ones.
Mitochondria (site of energy generation)
probably evolved from engulfed prokaryotic
organisms.
Chloroplasts (site of photosynthesis) probably
evolved from photosynthetic prokaryotes.
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Endosymbiosis
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Endosymbiosis (continued)
Multicellular organisms arose about 1 billion years
ago.
Cellular specialization—cells became specialized
to perform certain functions.
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Talking About Science: Stanley Miller’s
experiments showed that organic materials
could have arisen on a lifeless earth
Figure 16.3A
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• Simulations
of such
conditions
have produced
amino acids,
sugars, and
nucleotide
bases
CH4
Water vapor
Electrode
Condenser
Cold
water
H2O
Cooled water
containing
organic
compounds
Sample for
chemical analysis
Figure 16.3B
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The first polymers may have formed on hot rocks
or clay
• These molecules could have polymerized on hot
rocks or clay
– This could have produced polypeptides and
short nucleic acids
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The first genetic material and enzymes may both
have been RNA
• The first genes may have been RNA molecules
– These molecules could have catalyzed their own
replication in a prebiotic RNA world
2
Monomers
1
Formation of short RNA
polymers: simple “genes”
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Assembly of a
complementary RNA
chain, the first step in
replication of the
original “gene”
Figure 16.5
Molecular cooperatives enclosed by membranes
probably preceded the first real cells
RNA
• These molecules
might have acted as
rough templates for
the formation of
polypeptides
Self-replication
of RNA
Self-replicating RNA
acts as template on
which polypeptide
forms.
– These polypeptides
may have in turn
assisted RNA
replication
Polypeptide
Figure 16.6A
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Polypeptide acts
as primitive
enzyme that
aids RNA
replication.
• Surrounding membranes may have protected
some of these molecular co-ops as they evolved
rudimentary metabolism
– Natural selection would have favored the most
efficient co-ops
– These may have evolved into the first
prokaryotic cells
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Membrane
RNA
Polypeptide
Figure 16.6B, C
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