Transcript Chapter 16 student notes part 2

Darwin wrote up his observations and
conclusions (including evidence) in a book, but
waited 10 years to publish it
 ________________ independently arrived at the
same conclusions and sent him an essay to read
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 Known as the father of biogeography
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Darwin published ____________________the
next year, on ___________________________
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________________ : an individual’s adaptation to
the environment as measured by its relative
genetic contribution to future generations
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Descent with modification happens when:
_________________________________________
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500 years ago, Leonardo da Vinci questioned the
existence of __________________________________
Prevailing belief: deposited by an ancient flood
Rocks composed of cake-like layers; some contained
shells while others did not
Considered it to be similar to spring flooding of rivers
and the deposition of silt on riverbeds
If layers had been deposited over time, vertical
sequence of fossils would be a fossil record of past life
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By the 1700s, fossils were accepted as remains
or impressions of organisms that lived in the
past
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Fossil: from translation of Latin word meaning
__________________________
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Interpretation of fossils often influenced by
cultural beliefs
Most fossils are remains of __________________
________________________________________
 Trace fossils are indirect evidence obtained from
impressions
 Example: tracks
 ___________ are fossilized feces
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Why are fossils hard parts instead of soft matter?
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The ________________ process is very slow
Begins when an organism dies and is covered in ash
or sediment
Water infiltrates the remains, and metal ions or other
inorganic molecules replace the organic ones in
bones or other hard tissues
Soft tissues often decay
The pressure increases from additional sediment
deposited on top.
Pressure + mineralization = transformation of the
remains into stony fossils
 Fossilization is favored when remains are
___________________ and remain ____________
 These conditions are rare; therefore, fossils are
rare
 Also must remain undisturbed
 Scavengers and erosion often make this
difficult…
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Sediment particles (including silt, sand, volcanic
ash, and other particles) settle and become
compressed
Over time, the layers of sedimentary rock form in
varying thickness
___________________ : the formation of layered
sedimentary rock
The layers and their chemical/physical properties
provide context for the fossils found within them
Figure 16.10, page 247
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Currently more than 250,000 species of fossils
Fossil record will ___________ be complete
Unlikely that a fossil of each species that has ever
lived will be found
Favors species with hard parts, dense populations
with wide distribution, and that persisted a long
time
________________ (line of descent) of organisms
that were remote or lived for brief periods of
geologic time are less likely to be represented
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Fossil dating became more accurate with the
discovery of radioisotope decay
________________ : a form of an element with an
unstable nucleus that decays and becomes other
elements
Decay not influenced by environmental factors;
serves as a predictable and constant clock
Used to date fossils and rocks
More recent fossils may be dated using their ratio
of carbon isotopes (carbon dating)
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Early geologists counted backward through layers
of sedimentary rock to observe transitions in the
fossil sequence around the world
Similar transitions were observed in different
locations around the world
 These became the basis for divisions in the
___________________________
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A chronology of the Earth’s history
Boundaries for major intervals can be
determined by transitions in the fossil record
Major divisions can be correlated with
macroevolutionary events
Includes dates obtained by radiometric dating
_____________________ : major patterns,
trends, and rates of change among lineages
Geologic
time clock
Figure 16.13,
page 249
6.12, page 249
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Model suggests that all continents were part of a
large supercontinent called _______________
 Eventually split and drifted apart
 Gondwana: southern supercontinent
Jigsaw-like fit between the Atlantic Ocean
coastlines of South America and Africa
Helped explain why the same fossils appear in
sedimentary rocks on both sides of the ocean
This theory is called plate tectonics
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Movements of Earth’s tectonic plates on outer
layer of rock rafted land masses to new positions
Movements had profound impacts on the
directions of life’s evolution
Evidence for plate tectonics theory
 Distribution of global land masses
 Global fossil distribution
 Magnetic rocks found in different places around the
world
 Seafloor spreading from mid-oceanic ridges (fissures)
Figure 16.13,
page 249
a 420 mya
b 237 mya
c 152 mya
d 66 mya
e 14 mya
We now know that continents collide, split,
and move vast distances over the surface of
the Earth.
Continental drift (plate tectonics) influences
life and evolutionary forces on land and in
the oceans
________________ _______________ is the study
of body forms and structures of major groups of
organisms, such as vertebrates and plants
 Similarities between species may indicate
evidence of descent from a common ancestor
 _____________ _____________ : similar body
parts shared among related organisms
 The structures may be used differently, but the
same genes direct their development
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In time, isolated populations begin diverging
genetically
 Over time, differences appear in body form
 This macroevolutionary process is called
________________________________
 In spite of changes in form, a careful
examination reveals common heritage
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Example: the four-legged ancestry of land
vertebrates
Divergences led to the major vertebrate groups
Divergence seen in the five-toed limb
 The same five-toed limb has been modified into a
human arm, an elephant foot, or bird wing
Although they differ in use, size, and shape, they
retain the same structure and positioning of bony
elements
Figure 16.16, page 252
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Certain bones
were lost over
time
• Example: digits
numbered 1-5
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Bones of
forearms: colored
in orange and
pink
Stem reptile (a cotylosaur)
Figure 16.16, page 252
2
1
3
pterosaur
4
1
2
3
chicken
Figure 16.16, page 252
2
3
penguin
Figure 16.16, page 252
1
2
porpoise
3
4
5
Figure 16.16, page 252
1
2
bat
3
4
5
Figure 16.16, page 252
1
3
4
2
5
human
Figure 16.16, page 252
1
2
3
4
elephant
5
Figure 16.16, page 252
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Similar body parts are NOT always homologous and
do not always share a common lineage
They may have evolved independently in separate
lineages
_______________________ look alike in different
lineages but did not evolve in a shared ancestor
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____________________________: evolution of
similar body parts in different lineages
Example: ______________________________
 All act in flight but examination of their
structure reveals that they are not
homologous
 Unique adaptation for flight are evidence that
wing surfaces in bats, birds, and insects are
analogous
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Figure 16.17,
page 253