History of Biological Diversity
Evolution: Darwin’s travel
Developing the Theory of
Evolution
The Galápagos Islands
• Darwin noticed that the
different islands all seemed
to have their own, slightly
different varieties of animals.
• Somewhat similar species
that suited their particular
environment.
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Darwin’s Theory of Evolution by Natural Selection
Origin of Species: Darwin’s Book
In 1859 On the Origin of Species presented evidence and proposed a
mechanism for evolution that he called natural selection.
• Today, scientists use
evolution to mean
cumulative change in a
group of organisms through
time.
• Natural selection is not
synonymous with evolution
– it is a mechanism by
which evolution occurs.
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Darwin’s Theory of Evolution by Natural Selection
Peppered Moth: Natural Selection
• The light colored form was the predominant form in England prior to
the Industrial Revolution.
• Around the middle of the 19th century the darker form began to appear.
It was first reported in 1848. By 1895 98% of the moths in Manchester
were the dark variety.
• In recent years, the burning of cleaner fuels and Clean Air regulations
has reduced the pollution there and the lighter colored moths have
increased in numbers.
• First 5 minutes
• https://www.youtube.com/watch?v=aTftyFboC_M
Types of Selection:


a. Artificial Selection – humans select for variations
in plants and animals that they find useful.
b. Natural Selection
– also means “Survival of the Fittest”.
- Fitness in this sense does not mean strongest.
- Fitness in Darwin terms means reproduction. The one who
survives long enough to reproduce the most is the one with the
highest fitness.
Types of Natural Selection
-Evolution acts on the phenotype of the individual, not the
genotype.
 - There are 4 types of selection that can occur on a
population.

1. Directional Selection
 – when individuals at one end of the curve have a higher fitness than
individuals in the middle or at the other end of the curve.

 2.
Stabilizing Selection
 – when individuals near the center of the curve have higher
fitness than individuals at either end of the curve, narrowing of
the graph.
 3.
Disruptive Selection
 – when individuals at either end have a higher fitness and
individual near the middle of the curve are selected against.
- Over time with enough selection a population can go
through genetic drift.
a. genetic drift – random change in
allele frequency.
4. Sexual Selection: the ability to attract a mate
Worksheet
PAP and Academic
Support for Evolution
• Evidence for evolution comes from:
1. The fossil record: remains in layers of rock
2. Comparative anatomy
a. Analogous structures
b. Homologous Structures
c. Vestigial Structures
3. Comparative embryology:
4. Comparative biochemistry
5. Geographic distribution
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Evidence of Evolution
1. Support of Evolution: Fossil Record
• Fossil Record – Fossils
are the remains of
ancient organisms
found in layers of rock
in the Earth.
Support of Evolution
• The layers of rock
tell the history of the
Earth, while the
fossils found within
the rock tell a history
of life.
• The fossils are
thought to be the
same age as the rock
they are found in.
Support for Evolution: The fossil Record
• Researchers consider two major classes of traits when
studying transitional fossils:
• Derived traits are newly evolved features, such as
feathers, that do not appear in the fossils of common
ancestors.
• Ancestral traits are more primitive features, such as teeth
and tails, that do appear in ancestral forms.
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Evidence of Evolution
2. Support for Evolution: Comparative Anatomy
•
A. Homologous structures are anatomically similar structures inherited
from a common ancestor.
• Similar structures with different function (similar bones) (common
ancestor)
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Evidence of Evolution
Support for Evolution
Comparative anatomy
• B. Analogous structures
can be used for the same
purpose and be superficially
similar in construction, but
are not inherited from a
common ancestor.
• Structures are different but
have similar function
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Evidence of Evolution
Support for Evolution
Comparative anatomy
• C. Vestigial structures are structures that are the reduced forms of
functional structures in other organisms.
• Evolutionary theory predicts that features of ancestors that no longer
have a function for that species will become smaller over time until
they are lost.
snake pelvis
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human appendix
Evidence of Evolution
3. Support for Evolution: Comparative embryology
• Embryos of many
animals with back-bones
are very similar.
4. Support for Evolution: Comparative Biochemistry
• Common ancestry can be seen in the complex metabolic molecules that many
different organisms share.
• The more closely related species are to each other, the greater the biochemical
similarity.
Similarities in DNA
and protein sequences
suggest relatedness.
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Evidence of Evolution
5. Support for Evolution: Geographic distribution
• The distribution of plants and animals that Darwin were
what first suggested evolution to him.
• The distribution of plants and animals around the world is
studied in the field of biogeography.
• Evolution is linked to migration patterns, climate, and
geological forces (such as plate tectonics).
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Evidence of Evolution
PAP Activity
Academic Activity
Adaptation- an inherited trait that increases a
population’s chance of survival and reproduction
in a particular environment
• Fitness is a measure of the relative contribution
an individual trait makes to the next generation.
• The better an organism is adapted to its
environment, the greater its chances of survival
and reproductive success.
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Evidence of Evolution
Bird Beak Lab: ALL
PAP Webquest
Academic Webquest
• Through adaptations, populations often
become suited to a specific job called a niche.
• 1. niche – the role a population plays in a habitat
- job, profession, role
• 2. Competition arises when 2 populations
occupy the same niche.
Camouflage
Adaptation
Types of adaptations
• Camouflage is a suite of
morphological adaptations that allow
an organism to blend into its
environment.
• Mimicry is a type of morphological
adaptation where a species evolves
to resemble another species.
Mimicry
• Antimicrobial resistance develops in
some bacteria in response to sublethal exposure to antibiotics.
http://twentytwowords.com/can-you-find-the-hiddenanimals-in-these-20-wildlife-photos/
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Evidence of Evolution
Hide and Seek: ALL
Population Genetics - study of the traits in a population
A. Population – a group of interbreeding organisms (a species) living in a given
area
B. Gene Pool – combined genetic material of all the members of a population
C. Gene Flow-the transfer of allele or genes from one population to another
D. Genetic Drift- any change in the allelic frequency in a population that results
from chance
E. Allele – forms that a gene can take
F. Allele Frequency – the number of each allele for a
trait


2. This “changing of the gene pool” (allele frequency) has a name
—› Evolution.
3. Evolution – the changes in the gene pool of a population over
time.
– formation of a new species
Reproductive Isolation
 Speciation

- 2 or more species can not interbreed
Prezygotic: Its happens before fertilization: different
reproductive times and different mating songs.
Postzygotic: Its happens after fertilization: fertilization has
occurred but results in sterile offspring (Mule)
Horse 60 chromosomes--------gametes 30
Donkey 62 Chromsomes--------gametes 31
Combination 61 can’t divide
 1.
Behavioral Isolation/Temporal Isolation
- occurs when 2 populations are capable of interbreeding
but have differences in courting rituals or breed at
different times
 2.
Geographic /Allopatric Isolation
- 2 populations are separated by geographic barriers
●examples: rivers, mountains, bodies of water
Types of Evolution
Convergent Evolution: less alike to more alike
 Divergent Evolution=Adaptive Radiation: more alike to
less alike
 Coevolution: evolve together
 Punctuated equilibrium: happens in short period of time

Convergent Evolution:



Occurs when different organisms that live in similar environments become
more alike in appearance and behavior.
Less alike to more alike
Examples: - Bird wings/insect wings
- Shark fins/dolphin fins
Draw the diagram
in Notes
Divergent Evolution=Adaptive Radiation




One species give rise to many species
More alike to less alike
Also known as adaptive radiation.
Examples: - Darwin’s Finches.
- Brown bears and polar bears
Draw this diagram in
notes
Coevolution Add to notes

Co-evolution occurs when, two or more organisms evolve
together.
Gradual equilibrium

Predicts that little of evolutionary
change takes place in small gradual
steps
Punctuated equilibrium
 predicts that a lot of evolutionary
change takes place in short periods
of time tied to speciation events.
Types of Evolution; ALL
Teddy Graham Lab: PAP (If time permits)