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EQ’s 1-4
1. What happened at the Cambrian Explosion?
2. What happened at the K-T Boundary?
3. What were the first type of organisms on
Earth?
4. What does the endosymbiont theory?
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Land Conditions: Earth was molten
lava to start. Gravity started
pulling elements together. Crust
started to form
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Atmosphere conditions: Probably
were gases expelled from
volcanoes (water, CO2, sulfur
dioxide)
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MODERN EVIDENCE OF EARLY LIFE
Fossils- Any preserved evidence of
an organism by mineral
replacement, molds/casts, ice
mummies or amber.
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How does a fossil form? Organism
must die and be covered in
sediment quickly (near moving
water).
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On what parts of the Earth do we
find fossils? Areas that were
moving, shallow water when
those organisms lived.
Inside of cover
Steps to Fossils
1. Organism dies near/in water
2. Quickly covered in sediments
Inside of cover
3. Flesh decays, more sediments
4. Minerals harden in the bones
Inside of cover
5. Bones decay, only minerals are
left
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HOW OLD ARE THESE FOSSILS?
Relative Dating- Method used to
determine the age of rocks by
comparing them with other
layers.
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Radiometric dating- Uses the
decay of radioactive isotopes to
measure the age of a rock.
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Half-life- the known amount of
time it takes for half of the
original isotope to decay
(Uranium238 to Lead 206)
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How is the time scale organized?
It expresses the major geological
and biological events in Earth’s
history.
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Eon- Time is split into
PreCambrian and Phanerozoic.
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Era- The next largest division
(Dinosaurs=Mesozoic)
Period- the divisions of an era.
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Precambrian Era- The first 4 billion
years on Earth, prokaryotes 1st
then multicellular eukaryotes.
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Paleozoic Era- Major
diversification of body plans and
st
# of species. Life in oceans 1 ,
then moved to land. 2 mass
extinctions.
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Mesozoic Era- Early mammals 1st,
then dominated by reptiles
st
(dinosaurs). 1 flowering plants
and birds.
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Cenozoic Era- Mammals are
dominant life-form, diversified
quickly
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Cambrian Explosion- When
ancestors of most animal groups
diversified.
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K-T Boundary- Layer between
Mesozoic and Cenozoic eras.
Evidence of impact event
(iridium).
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Plate Tectonics- Movement of
large continental plates.
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Origins of Earth
Spontaneous Generation- Idea
that life arises from non-life.
Example- mice came from damp
hay and corn
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Theory of Biogenesis- Only living
organisms can produce other
living organisms.
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How did complex molecules join
together?
Primordial Soup Hypothesis- If
early Earth had mix of gases,
organic cmpds could be made by
reactions in the oceans.
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Deep-Sea Vents- Some believe
that these reactions began here,
where sulfur forms the base of
the food chain.
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Order of Organic Molecule
Organization
1. The first organic molecules
originated
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2. Formation of proteins
3. Genetic code that could
produce these proteins.
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4. Formation of membranes,
molecules become cells
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Cellular Evolution
1. 1st cells were prokaryotes
(bacteria), very simple with no
nucleus or cell parts. Similar to
archaea bacteria (thermophiles)
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2. Photosynthesizing ProkaryotesArchaea used sulfur for food, next
organisms used light
(photosynthesis)
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3. Endosymbiont TheoryAncestors of eukaryotes lived in
association with prokaryotes.
Explains DNA in chloroplasts and
mitochondria.
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Evolution- Idea that organisms
CHANGE OVER TIME as a result
of “genetic variations” enabling
them to ADAPT to changing
environments.
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Evolution explains…..
a. How living things develop from
ancestors
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b. How Earth came to be
populated by species
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Evidence for evolution can be seen
in….
a. Cell similarities in all life
b. Similar proteins in all cells
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c. Many species disappearing
from Earth
d. Living species being different
from ancestors
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• Organisms being suited to
environments
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• Extinction- When a species that
once lived on the Earth no longer
exists. Death rate is higher than
birth rate
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• In 1859, Charles Darwin
published his book On the Origin
of Species on evolution. Darwin
was a naturalist on the HMS
Beagle, a ship that sailed around
South America into the Pacific
Ocean.
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• On his trip, Darwin collected
many different samples of
organisms. From these, Darwin
made observations and thoughts
on evolution (change).
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One Important Stop: Galapagos
Islands
a. Location of islands- far enough
from South America to make it
difficult for organisms to get
there from mainland.
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• b. Islands are separated from
each other, keeping them
isolated.
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• b. Islands are separated from
each other, keeping them
isolated.
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• c. Numerous number of finch
species with differences in beak
shape.
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People who affected Darwin’s
Work
a. Charles Lyell- Described the
processes of how landforms are
formed. He believed these
processes took millions of years.
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b. Alfred Russell WallaceDeveloped his own theory of
evolution, which was similar to
Darwin’s.
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• c. Thomas MalthusMathematician who explained
how the human population had
the potential to reach huge
numbers in a short time period.
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DARWIN’S CONCLUSIONS
Struggle for Existence: The
struggle of all organisms in the
environment to fulfill ALL of their
survival needs.
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What needs do organisms fight
for?
a. Food
b. Space
c. light
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d. Water
e. Minerals
f. oxygen
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# of Parents
Asexual=1
Sexual=2
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Traits
Asexual- same as parent’s traits
Sexual- mixture of DNA from both
parents
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Less or Greater Variation
Asexual- less
Sexual- greater
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• Mutation: A sudden change that
occurs in the genetic material of
an organism. This change may
produce a small or large change
in the organism
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Types of Genetic Variation:
1. structural/anatomical change
2. Physiological change
3. Behavioral change
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4. Chromosomal/gene change
5. Molecular change
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Most Important Types of Genetic
Variation
a. Chromosomal
b. Molecular
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• Why? These variations are
changes in genetic code
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• What drives evolution? Changes
in genetic code.
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Darwin’s Two Clear Facts
1. There is a struggle for existence,
which limits the number of
surviving offspring.
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• 2. There are differences among
offspring due to individual
variations.
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• What determines which
individuals survive to reproduce
and thus become the parents of
the next generation? The
individuals whose genetic
variations allow them to compete
for their needs the best.
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• Natural Selection: The process by
which organisms that have the
best adaptive traits for an
environment are more likely to
survive and reproduce (survival of
the fittest).
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• Adaptations: Special
characteristics that make an
organism well suited for a
particular environment.
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***WRITE THIS ON BOTTOM***
Natural Selection- environment
chooses the best traits.
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How do organisms evolve the adaptations that
enable them to survive so well in a particular
environment?
Adaptations randomly occur due to
random changes in genetic material
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How do organisms evolve the adaptations that
enable them to survive so well in a particular
environment?
Adaptations randomly occur due to
random changes in genetic material
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• Selective Breeding: The breeding
of organisms by humans to
produce a specific trait. HUMANS
SELECT TRAITS, NOT
ENVIRONMENT
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Examples
a. Dogs
b. Cattle
c. vegetables
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d. Fruit
e. horses
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• What happens to undesirable
traits? They are selected to be
removed by humans and
replaced with desirable traits.
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Genetic Variation
Reproduction: fusion of gametes
that leads to small differences
between the offspring and it’s
parents.
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Genetic Variation: The small
differences in a trait of a species
that allows it to adapt to
environmental changes.
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• Overproduction: The production
of offspring that are too
numerous to live. They die due
to: disease, predation,
environmental factors. EX.-sea
turtles
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• Competition- Struggle between
individuals of the same or
different species to fulfill their
own needs by obtaining limited
available resources.
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What other factors add to the
struggle for existence for
individual species?
a. Predators
b. parasites
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c. Diseases
d. Climate extremes (hot/cold)
e. Flood
f. drought
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What 2 things are explained in
Darwin’s book, On the Origin of
Species?
1. how natural selection might
operate
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• 2. Provides evidence that
evolution occurred
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• What is a theory? It provides an
explanation for how some aspect
of the natural world operates.
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• What does the theory of
evolution state? It states that all
organisms on Earth have
descended from a common
ancestor.
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• In Darwin’s theory of Natural
Selection, what aspect of
evolution could Darwin not
explain? Sexual reproduction
/genetic basis for variation
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• Why could he not explain this
aspect? DNA was not discovered
as the genetic material until the
next century.
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Evidence of Evolution
1. Fossil Record- Provides a record
of species that lived long ago so
we can compare old species with
new ones.
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• 2. Comparative AnatomySimilar parts of different species
have different functions but are
constructed similarly.
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• 3. Comparative EmbryologyComparing different species’
embryos to find
similarities/differences.
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• 4. Comparative BiochemistryComparing DNA, enzymes and
other molecules for
similarities/differences
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• 5. Geographic distributionSpecies will have more
similarities to species that are on
the same continent.
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• Homologous structures- Features
in different species that have the
same evolutionary origin, but
may perform different functions
at the present time.
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• Convergent Evolution- Process
where unrelated species evolve
similar characteristics that help
them survive in similar
environments.
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• Analogous structures- Features
in different species that have
different evolutionary origins but
serve similar functions (ex.
Wings of fly vs. bird)
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Primitive trait- a trait that evolved
in an early, common ancestor
Examples: five digits on feet
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Advanced trait: A trait that is
modified by evolution to be
different from the primitive trait
it evolved from.
Example: hooved animals
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• Fossils- traces or remains of dead
organisms, preserved by natural
processes.
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• What parts of an organism are
usually fossilized? Bones and
other hard parts of their bodies
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What organisms/parts are found in
these examples?
a. Amber- insects, leaves, small
lizards
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• Ice- wooly mammoths
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• c. Mineral replacement in
sedimentary rocks- Once buried
in sediment, its tissues are
replaced by minerals.
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• d. Mud impressions- mud
hardens, plant/animal remains
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• d. Mud impressions- mud
hardens, plant/animal remains
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• What type of rock do you find
fossils in? sedimentary
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• Where does this rock need to
develop near in order to create
fossils? Stream, river, lake
(sedimentation)
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• What has to happen to the
carcass quickly in order to create
fossils? It must be buried in
sediments
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• What type of sediment layers
would you find fossils in?
Sandstone or mudstone
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• Vestigial Structures: Structure
with little/no function in an
organism, but is clearly related to
a more developed structure in
another organism
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Examples of Vestigial Structures
a. Human appendix
b. Snake’s tiny leg bones
c. Cave salamander’s eyes
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Embryology: the study of
organisms at very early
developmental stages to find
similarities/differences in species.
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How do organism similarities in both
anatomy and embryology provide
evidence for evolution? Similarities in
species’ anatomy and
embryology shows how they
changed from a common
ancestor
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Biochemistry-Studying the
molecules that make up
organisms (DNA, proteins,
enzymes, hormones)
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Examples: studying protein
interactions with antibodies,
comparing hemoglobin of
apes/man
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Microevolution: Change in species
with adaptations best suited for
the environment over a SHORT
TIME and on a SMALL SCALE
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Macroevolution: Change in species
to the environment over a LONG
TIME on a LARGE SCALE.
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Peppered Moth Story:
Before Industrial revolution- gray
colored moths favored for
camouflage on tree bark.
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After Industrial revolution: Tree
bark is now darker from soot,
darker colored moths become
favorable
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Were dark colored peppered
moths always present? yes
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Why were there more dark colored
moths in the population after
industrialization? They “fit” the
environment better
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What was the selective agent for
this change? The color of the
tree bark
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Industrial Melanism: When
populations near polluted areas
evolve to have darker (more
protective) coloring than those in
less polluted areas.
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***Write this on the bottom***
Light colored moths will still be
born because that trait is still in
the DNA.
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Biogeography: Comparing the
distribution of plants and animals
on one continent to another
continent.
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Example:1. The South American
mara compared to the European
rabbit. They do not have similar
ancestor.
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2. How did species of plants or
animals reach the Hawaiian
Islands? Either Asia or North
America
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Best Example for Darwin:
Comparing animals on the East
coast of South America to the
animals on the West coast.
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• Adaptation- small changes in the
same trait of an organism
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• Of the five types of evolution
evidence, what was not available
to Darwin? Biochemistry, no
genetic basis
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Fitness- measure of a trait’s
relative contribution to the
following generation.
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Camouflage- adaptations that
allow an organism to blend into
their surroundings.
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Mimicry- 1 species evolves to
resemble another 1 for
protection.
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Antimicrobial resistance- humans
use antibiotics that kills most
bacteria. Resistant bacteria
breed and cause outbreaks.
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Speciation: Process of evolution
where new species form that are
better suited to a changing
environment.
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Morphology: The changing of
shape and/or structure of an
organism in response to a
changing environment.
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Example: Leaves
a. Desert
b. Deciduous
c. Taiga
d. Tropical
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Physiology: The way an organism
and it’s internal parts function at
a cellular level (cells, tissues,
organs)
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Speciation
Species: A group of related
organisms that can breed and
produce fertile offspring.
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Reproductive Isolation: When 1
population of a species is
prevented from breeding another
population. Can lead to
speciation.
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How does a population of
organisms change? As genetic
traits common to the population
change.
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Genetic Drift: The process by
which allele frequencies change
over time due to changes in the
environment.
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Founder Effect: When a
population has a very different
gene pool from it’s parent
population because it descends
from only a few ancestors.
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Bottlenecks: Process where a
genetic makeup of a population
changes because all but a few
individuals have been eliminated.
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Gene Flow: Movement of alleles
into and out of a population as
individuals move in and out of a
population
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Geographic Isolation:
Reproductive isolation that is
caused by a geographic barrier
keeping 2 populations of a
species apart.
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Name physical barriers:
a. Mountain tops
b. Isolated lakes
c. Forests between grasslands
d. islands
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What leads to different beaks on
the finches of the Galapagos
Islands? Variations in food
sources on different islands.
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If a seed-eating finch lives on an
island with only insects to eat,
what are his choices for survival?
Move to another island or starve
**some might have beak
adaptation to stay**
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Divergent Evolution
Adaptive Radiation: Process by
which several species evolve from
parent species, adapting to
different ecological niche
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Examples: reptiles to turtles,
lizards, crocodiles, dinosaurs and
eventually to birds
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Convergent Evolution
Parallel Evolution: Where 2 or
more species evolve separately,
but in similar ways
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Examples: birds and flying insects
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Coevolution: Process by which two
or more species evolve in
response to each other.
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Example: many insects and flowers
(pollination)
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Gradualism: Process by which
species evolve at a continuous,
slow, steady pace
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Punctuated Equilibrium: When
species undergo little or no
change for long periods of time,
then evolve via sudden changes
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Stabilizing selection- when
organisms with extreme forms of
a trait are removed.
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Directional selection: population
shift towards extreme version of
a trait
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Disruptive selection: when
average traits are removed,
creating 2 populations of
extremes
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• Sexual Selection: change in
frequency of trait based on
competition for a mate.
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Extinction
Why does this happen?
a. Death rate higher than birth
rate
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b. Disease
c. More predators
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Mass Extinction: When a high
percentage of species die out at
the same geological time period.
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When was the last two mass
extinctions?
a. End of Permian Period-240
millions years ago
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b. End of Cretacious Period-65
million years ago