Download Unit 5 (ch 13&14)

Evolution
Chapter 13
“A change over time”
http://www.youtube.com/watch?v=FT3FU2XOgo
 http://www.hulu.com/watch/403434#detail
s=expand
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The Theory of Evolution
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Evolution literally means to change over
time.
A theory is a well supported, testable
explanation that observes observations
from the natural world
Questions that evolution attempts
to answer.
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How do species adapt to changes in the
environment?
How do new species develop?
Charles Darwin
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1809-1882
Studied to be a doctor
and a minister
1831 sailed around the
world as a naturalist on
the HMS Beagle
HMS Beagle
Darwin’s Voyage
Galapagos Islands
Galapagos Islands
15-2 Darwin’s Influences
James Hutton
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Geologist
Proposed that the earth was
millions of years old based
on geologic evidence
Sir Charles Lyell
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Geologist
 Proposed that geologic
changes occur slowly over long
periods of time.
 Darwin read his book,
Principles of Geology, on the
Beagle
Jean Baptiste Lamarck
French Naturalist
Published his ideas on
evolution in 1809 in
Philosophie zoologique
Lamarck’s Hypothesis
Organisms Strive for Perfection – all
individuals are trying to better themselves
Lamarck’s Hypothesis
Use and Disuse –
If an individual uses a trait it will be more
useful
If an individual does not use a trait it will
decrease in usefulness
Lamarck’s Hypothesis
Inheritance of Acquired characteristics
Analyzing Lamarck’s Hypothesis

There is no evidence to suggest that plants
and animals are trying to improve
themselves
Analyzing Lamarck’s Hypothesis
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Use and disuse do not change all
characteristics
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Stretching will not make you taller
Reading will not make your eyesight better
Analyzing Lamarck’s Hypothesis
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Acquired characteristics are not inherited
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A mouse that loses its tail will still produce
offspring with tails
Erasmus Darwin
Charles Darwin’s
Grandfather
Physician and Scientist
'All vegetables and
animals now living
were originally derived
from the smallest
microscopic ones.'
Thomas Malthus –
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Economist
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Human Population would be
limited
Starvation
 War (Competition)
 Disease
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15-3 Darwin Presents His Case
Alfred Wallace
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Developed his own theory
of Natural Selection
Contacted Darwin
This caused Darwin to
finally publish his theory
with Wallace
On Origins of Species
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After publishing with
Wallace, Darwin submitted
all of his ideas in a book
titled On Origin of Species,
By Means of Natural
Selection in 1858
Artificial Selection

Darwin was influenced to believe change
was possible because of the humans
selecting for traits in plants and animals.
Darwin’s Theory
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Evolution “Change” is driven by natural
selection
Summary of Darwin’s Theory
Variation

There are differences within a population
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Mutation and Sexual Reproduction
Competition for resources
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Not all offspring will survive
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Starvation
Overcrowding
Predation
Fitness
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Some of the variants will have an
advantage over the others, they will survive
and produce more offspring
Reproduction and Inheritance
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These advantages will be passed on to the
next generations
Descent with Modification
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Species alive today are descended with
modification from ancestral species
Tree of Life
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All species are connected on a single tree
of life
Modern Theory
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Mendel’s discoveries in genetics explained
a great deal in evolution
Evidence for Evolution
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Fossil Record
Anatomy
Development
Molecular Evidence
Fossil Record
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Since most of the “ancestor” species are
extinct, fossils are the only evidence that
can be examined.
Intermediate “missing link” fossils are very
informative
Archaeopterix
A fossil of a bird like creature
Has feathers, teeth and claws in its wings
Whale Ancestors
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http://www.youtube.com/watch?v=lx079oE
gKKs
Anatomy
Structures similarities in body structure
indicates organisms are related
Homologous Structures
Structures that have common function and
design (ancestry)
Vestigial Organs
Structures that have reduced size and or
function
http://www.youtube.com/watch?v=pbc7ee9u1
JE
Developmental Evidence
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Similarities in embryonic development are
interpreted to mean closer relationships.
Developmental Evidence
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Similarities in embryonic development are
interpreted to mean closer relationships.
Molecular Evidence
Organisms are considered to be more closely
related if
DNA sequences in genes are more similar
Amino acid sequences in proteins is more
similar
Molecular Evidence
Organisms are considered to be more closely
related if
DNA sequences in genes are more similar
Amino acid sequences in proteins is more
similar
Strengths of Darwin’s Theory
Many discoveries in Physics, Geology and
Biology have supported and expanded
Darwin’s ideas
Strengths of Darwin’s Theory
Many discoveries in Physics, Geology and
Biology have supported and expanded
Darwin’s ideas
Weaknesses of Darwin’s Theory
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Researchers still debate how new species
arise and how they become extinct.
The origin of life is still very uncertain
Evolution of
Populations
Chapter 14
Genes and Variation
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Variation – differences between individuals
of a species
Produced by two processes
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Mutation – random changes in DNA
Sexual Reproduction- combining genes from two
gametes
Single Gene Traits
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Several traits are controlled by a single
gene and are either dominant or recessive.
Polygenic Traits
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Poly-genic means “many genes”
Most traits are controlled by several genes
and can show up in many different forms.
Normal Curve
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Most individuals are intermediate, extremes
are less common
Microevolution
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Micro – small
Microevolution is change within a species
Gene Pool – all of the genes in a
population
Allele Frequency – how many times a
certain allele shows up in the population
Microevolution
Any change in Allele frequency in a
population is considered
microevolution
English Peppered Moth
The English Peppered Moth
The moth was usually white with dark spots
During the Industrial Revolution (1850’s)
soot covered many of the white barked
trees
More and more dark colored moths appeared
at the same time
Kettlewell’s experiments suggested this was
due to natural selection
English Peppered Moth
The English Peppered Moth
The moth was usually white with dark spots
During the Industrial Revolution (1850’s)
soot covered many of the white barked
trees
More and more dark colored moths appeared
at the same time
Kettlewell’s experiments suggested this was
due to natural selection
Microevolution in Humans
Sickle Cell Anemia is a recessive (hh)
disease found mainly in Africa
A carrier (Hh) for the disease has resistance
to malaria
Delta 32 Mutation
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Delta 32 mutation occurs in 10-15% of
whites of European descent
This mutation gave resistance to the plague
Most of the people without this allele died
of the plague causing the allele frequency
to rise
The mutation also gives resistance to HIV
infection
Selection
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Selection can be one of 3 forms
 Directional
 Stabilizing
 Disruptive
Stabilizing Selection
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Both Extremes are selected against
The population is stabilized
Directional Selection
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One of the extremes is selected against,
the population shifts away
Disruptive Selection
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The most common variation is selected
against spitting the species two groups
Genetic Drift
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In small population individuals may pass on
more genes by chance. This is called
genetic drift.
Large populations are not affected by
genetic drift
Population 18
Genetic Drift
9 Heads
9 Tails
Population 18
6 Heads
12 Tails
Can a species stop evolving?
Hardy Weinberg equilibruim
in order for evolution of a species not to
occur
(all allele frequencies stay the same)
5 evolutionary forces must not act
Hardy Weinberg Equilibrium
Populations do not evolve if there is
Random Mating
no movement into or out of the population
no genetic drift, large population
no natural selection
no mutation
16-3 The Process of Speciation
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Speciation –the production of a new
species
Species – a group of individuals that
reproduce in nature and produce fertile
offspring
Isolation – the factor that prevents the new
species from reproducing with the ancestral
species
Behavioral Isolation
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Mating songs or rituals are different, so the
two species don’t interbreed
Behavioral Isolation
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Groups are not attracted to each other for
mating
Geographic Isolation
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Groups are physically separated and no
longer interbreed
Temporal Isolation
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Groups reproduce at different times of day
or year
Mechanical Isolation
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Structural differences prevent mating
between individuals of different groups
Ecological Isolation
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Groups are adapted to different habitats,
hybrids aren’t adapted well to either
Reproductive Failure
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Mating between groups fail to produce
fertile offspring
Speciation Continued
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Once populations are isolated, different
pressures select different traits
When the populations will no longer
interbreed, new species have been formed
Natural Selection - 2 forms
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Ecological Selection – better suited to
survive in the environment
Sexual Selection –
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Males compete for access to females
Females select males with “good gene” markers
Sexual Dimorphism
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Dimorphism di-morph-ism
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Two forms
Males are usually larger
Males would have ornaments (antlers, manes,
colors)
Patterns of Evolution
Macro Evolution
Macro – Large
Idea that species can split to form new
species
All life forms are related through a common
ancestor
Divergent Evolution
Similar species develop different adaptations
to different environments
Convergent Evolution
Two species develop similar adaptations to
the same environment.
Coevolution
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Two or more species adapting to each
other
Rate of Evolution Slow and Steady
or in Spurts?
Gradualism – the idea that small changes
build up slowly over time to produce large
changes.
Expectations – many intermediate “missing
link” fossils
Punctuated Equilibrium
The idea that populations go through periods
of stability followed by short periods of
rapid change.
Expectations – fewer intermediate fossils
Endosymbiont Theory
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Endo –inside
Symbiont – symbiotic “mutualistic”
relationship
Endosymbiont Theory
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This theory suggests that mitochondria and
chloroplasts were once independent living
organisms
These organisms were “eaten” by larger cells,
but remained alive
Endosymbiont Theory
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Evidence for endosymbiosis
Each mitochondrian has its own circular chromosome of DNA
Very similar to a bacteria
Reproduce on its own
Ribosomes are very similar to bacterial ribosomes