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What is Evolution?
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What is Evolution?
• A process of biological change over
generations that makes descendants become
gradually different from their ancestors
• Charles Darwin gets much of the credit for the
theory of evolution
TO DO!
• Look in your Biology book on pages 298-299
• Grab a partner and list each of the four names
below and write a sentence or two describing
how each person contributed to the theory of
evolution.
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Carolus Linnaeus
Georges Louis Leclerc de Buffon
Erasmus Darwin (Charles’ grandfather)
Jean-Baptiste Lamarck
Carolus Linnaeus’s Ideas
(A Swedish Botanist during the 1700s)
• He put organisms into groups based
on physical characteristics
• He created the Linnaean system of classification
has 7 levels: Kingdom, Phylum, Class, Order,
Family, Genus, Species
• He is also responsible for: binomial
nomenclature—a 2 word system of naming
(written in Latin because it is not used)
Georges Louis Leclerc de Buffon’s
Ideas:
(A French Naturalist of the
1700s)
• Said species shared
ancestors instead of
forming separately
Erasmus Darwin
(Charles’s grandfather)
(An English doctor & poet born in 1731)
• Said that living things are descended
from a common ancestor
• He suggested that more complex
forms of life came from more simple
ones
• He did not believe in extinction, just
in species evolving into something
else
Jean-Baptiste Lamarck’s Ideas:
(A French Naturalist who made
his theories known in 1809)
• Organisms evolved towards
being perfect and complex
• Species do not become extinct,
they just evolve
• Adaptation is a result of change
caused by environmental
change
• Organs and structures changed
in regard to use or disuse and
changes are passed on to
offspring
Charles Darwin
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1809-1882
British naturalist
Proposed the idea of evolution by natural selection
Collected clear evidence using live organisms AND
fossils to support his ideas
Charles Darwin
• Darwin traveled to many places to research
his theories on evolution.
• When he visited the Galapagos Islands he
noticed a wide variety of traits among similar
species.
Example -- Darwin
noticed that the island with
short-necked turtles had
vegetation lower to the
ground while the
island with the longnecked turtles had taller
vegetation
Video
Galapagos Islands (on Safari)
1. All individuals in a population have variations.
2. Some of these variations allow
individuals to successfully compete.
3. Those that “win” at competition are
able to eat to survive.
4. The individual is able to reproduce and pass their
variations on to their offspring.
Darwin called this:
Artificial Selection —when humans determine which traits
are favorable and then breed organisms that show those
traits
Heritability – the ability of a trait to be passed down from
one generation to the next
Natural Selection – a mechanism by which individuals that
have inherited beneficial adaptations produce more
offspring on average than do others
4 Main Principles to the
Theory of Natural Selection
1. Genetic Variation
2. Overproduction
3. Adaptation
4. Descent with
modification
1. Genetic Variation
Variations can:
• Increase the fitness (ability to survive) to the environment
• Increase the chance for reproduction/ survival & passing on genes
• Be a product of evolution by natural selection
Genetic variation refers to diversity in genes and can refer to differences
between individuals or populations.
Mutations and sexual reproduction are the main things that cause genetic
variation.
In order for the variation to
continue the organism must
compete, reproduce and feed
successfully
Example: size of moose’s antlers,
coloring of a mouse
2. Overproduction
While producing many offspring give an advantage of
species survival the offspring also are in more
competition for food/resources
3. Adaptions
These are physical or behavioral changes in organisms that
actually help some organisms survive better. Example: Panda’s
wrist acts as thumb (see page 309 for picture)
4. Descent With Modifications
This means that adaptive traits that help the
organism survive will be passed on to the next
generation and more of the organisms will
show that helpful trait in each of the
generations that follow after that.
Check out this 10 minute clip about how some mice had a mutation in
fur color that helped them evolve into two different populations of
mice
http://www.hhmi.org/biointeractive/making-fittest-natural-selectionand-adaptation
Peppered Moth activity
3 TYPES OF ADAPTATIONS:
1.Behavioral
2.Physiological
3.Structural
1. Behavioral
Involves the way an organism
acts in response to an it’s
environment
Examples: birds migrate, bears
hibernate, salmon swimming to
spawning ground
2. Physiological
Involves the function of a trait
Examples: venom of snakes
or the ink of octopus, etc.
3. Structural
Involves the anatomy of an organism
Examples: bird’s beak, horse's hoof,
anteater snout, etc.
“Survival of the Sneakiest”
activity
Evidence of Evolution
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Fossils
Geography
Embryology
Anatomy
DNA Sequence

new layers of rock
cover older ones,
creating a record over
time
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fossils within layers
show that a
succession of
organisms have
populated Earth
throughout a long
period of time
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The fossils are lined
up according to TIME

Similarities and
differences are
noted between
fossils
GEOGRAPHICAL EVIDENCE
• Different places have different
plants, animals and climates
even if they share similar
ancestors
• When Darwin visited the
various islands on his voyage
to the Galapagos islands he
found that similar organisms
had different traits that
helped them survive in their
particular environment.
Example: finches on certain
Galapagos islands have beaks of
different sizes though they have the
South American Finch as their
common ancestor
EMBRYOLOGICAL EVIDENCE
• Similar embryological development in closely
related species
– all vertebrate embryos have similar structures at
different stages of development
All of these creatures have gill pouches as embryos
This suggests a common ancestor that lived in the sea
ANATOMICAL EVIDENCE
Homologous Structures =
similar shape, but different
modern function
Examples: Similar forelimb bone
structures for human, cats, whales,
& bats suggest they shared a
common ancestor a long time ago
Vestigal Structures =
Remnants of organs or
structures that had a
function in an earlier
ancestor (evidence of
change over time)
Examples: some snakes & whales show
remains of the pelvis & leg bones of
walking ancestors, eyes on blind
cave fish, human tail bone
Evolutionary Biology Today
• Fossil evidence is still used
• Molecular and genetic evidence supports fossil and
anatomical evidence
Example: 2006 fossil
discovery of an early
tetrapod links sea
animals & land animals
DNA Sequence Evidence
DNA sequence analysis - The more related two organisms are,
the more similar their DNA sequences will be
Example: Giant Panda is more
closely related to bears than
raccoons
Interactive Game:
“Who Wants to Live a Million
Years?”
http://www.sciencechannel.com/games-andinteractives/charles-darwin-game.htm
Evolution of Populations
• Genetic variation in a population = lots of different
traits in a certain group of animals or plants
• The more variation, the better the chance that the
species will survive
Genetic variation is in the
group’s gene pool …that is
the combined genetic
traits of all the individuals
in that group
Where does genetic variation come from?
1. Mutation – a change or mistake
in the Genetic sequence/DNA
2. Genetic Recombination – New
combinations of the genetic
alleles from parents
(Example parents might have genetic
letters BB and bb but the daughter or
son would have Bb…same letters,
different order or “combination”
A Type of Natural Selection:
Sexual Selection
Occurs when certain traits
increase the success of sexual
reproduction
1. Competition among males
for a mate
2. When males display certain
traits that attract females
How do humans decide who they
are attracted to???
How do you think cosmetic surgery or
medicine effects natural selection in
humans??
Factors That can Lead to Evolution
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Genetic Drift
Gene Flow
Mutation
Sexual Selection
Natural Selection
• We have already learned about mutations, sexual
selection, and Natural Selection but what are
genetic drift and gene flow????
Genetic Drift--The frequency that genetic traits show
up by CHANCE (like a genetic lottery)
Gene Flow--As individuals or small groups move
between different populations, they can affect the
genetic traits that begin showing up in the
populations
Isolated Populations
When a population becomes “isolated” that means
that they no longer mate with other populations
Isolation can eventually cause
populations to become
different species
over time
Why does this occur?– not physically able to mate with
other populations, behavioral differences, geographic
separation, or their timing is simply “off”
Species Can Affect Each Other
• This happens in life…organisms compete for food
with their neighbors or are predators/prey for
certain other organisms nearby….In order to
survive, they adapt
Example: If you and your new college roommate both
like Pizza Rolls but you only get one
box a week and he hogs them all,
maybe you would opt for
frozen burritos after being hungry
for a while!
Clip on Galapagos Island Finches
(13 minutes):
http://youtube/n3265bno2X0
Hawaiian Birds Evolution
Article and Questions
Extinction
• Background extinction – extinction that occurs
in smaller amounts of species all the time but
at a low rate
• Mass Extinction – extinction that is more rare,
often at a global level (example: mass
extinction of dinosaurs)
The History
of Life
Scientists can
trace how
organisms
have evolved
over the years
by looking at
the geologic
time scale
FYI!
A wide variety of living organisms have
inhabited Earth over millions of years
Many species went extinct at different
points in Earth’s history
Human beings have only been around
for the last 10,000 years
97% of all things have died out
Quagga extinct1880
Passenger Pigeon
extinct 1914
Javan Tiger extinct: 1979
The Golden Toad
Evolution Flashcards
&
Activity: An Evolutionary
Experiment