16.4 Evidence of Evolution

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Darwin’s Theory of Evolution Note Outline
Goal: to understand how natural selection is the driving
force that has caused organisms to change over time.
Chapter 16.1 Darwin’s Voyage of Discovery
Darwin’s Epic Journey

Geologists were just beginning to suggest that the earth was
_______________ over time. Biologists were suggesting that
________________ would explain how modern organisms
evolved over long periods of time through descent from a
common ancestor.
Observations aboard the Beagle

As Darwin travelled aboard the Beagle he observed three distinct
patterns of biological diversity; species vary ___________, species
vary ___________ and species vary _________ __________.
Species Vary Globally
o Darwin noticed that similar yet ____________ animals
inhabited similar habitats around the world.
Example: flightless, ground dwelling birds (rheas) lived in grasslands of
South America. They looked and acted like ostriches but ostriches could
only be found in Africa. Darwin also found emus in Australia’s grassland
and they too were similar to ostriches.
Species Vary Locally
o Darwin noticed different, yet related, animals lived in
____________ habitats within a local area.
Example: while travelling the Galapagos Islands Darwin noticed that
island slightly differed in their ecological conditions. He found giant
tortoises varied slightly in
their shells from island to
island.
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Species Vary Over Time
o Darwin collected fossils and he noticed that
some fossils of extinct animals were
____________ to living species.
Example: A fossil of a giant armoured animal was very similar to that of a
present day armadillo.
16.2 Ideas That Shaped Darwin’s Thinking
An Ancient, Changing Earth

Hutton recognized that certain _____________ ___________
were responsible for certain geological features.
Example: Hutton proposed that forces pushed the earth surface upwards
and this gave rise to mountains.

Lyell’s principle of ____________________ stated that geological
processes we see today must be the same forces that shaped
earth millions of years ago.
Example: ancient rivers carved channels and canyons just as our present
rivers do today.

Darwin realized that if _____________ could change over time
___________ _________ could change over time.
Lamarck’s Evolutionary Hypothesis

Lamarck suggested that all living things urge to become more
___________ and ___________-. As a result organisms change
and acquire characteristics to make them more successful in their
environment. This was known as “___________ __________”.
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Example: the black – necked stilt’s long legs were a result of the bird’s
ability to stretch their legs. Over time, future generations would have
their legs could get longer.

Lamarck also suggested that these acquired traits could be passed
on their offspring. This was known as “____________ ___
______________ ______________”.
Population Growth

Malthus suggested that human populations tend to grow
_________ than food supply. He reasoned that war, hunger and
disease would keep population in __________.

Darwin reasoned that the same notion could be true for other
___________. He wondered why others of a same species
____________ and others perished.
Artificial Selection

Darwin took up breeding plants and pigeons to test the idea of
_____________ ___________. The animals and plants provided
the variations and humans selected those variations they find
useful.

Darwin realized that variation in a population provided the raw
material for _______________.
16.3 Darwin Presents His Case
Evolution by Natural Selection

Darwin used Malthus’s reading to come up with the notion of a
struggle for ________________. All members of a population
must compete for necessities of life.
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
Darwin thought that the ______________ in a population played
a role in who survived. Some variations are better suited for the
environment than others and this increased the organism’s ability
to live and _____________. These organisms had better
adaptations.

Those organisms with the best _____________ were more likely
to reproduce, meaning they had better fitness. The difference in
reproduction rates refers to the “_________________________”.

Natural selection takes into account that there are
_____________ in a population, those best suited will survive and
produce more offspring. From generation to generation,
populations continue to change as they become better
__________, or as the _______________ changes.
Common Descent

Darwin suggested that over many generations, adaptations could
cause successful species to evolve into new __________. This
explains the diversity of life and that species change over time.

___________ with ____________ proposes that all living species
are descended from common ancestors. A tree of life links all
living things.
16.4 Evidence of Evolution
Biogeography

________________ is the study of where organisms live now and
where they and their ancestors lived in the past.

Darwin saw two patterns related to biogeography. One pattern
had closely related species ___________ slightly when the climate
changed. Populations on islands were slightly different from the
mainland species.
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
The second pattern had very distantly related species develop
______________ in similar environments. Similar habitats around
the world had similar plants and animals that were very distantly
related. Darwin suggested that ________________ pressures had
caused very distantly related species to develop similar
________________.
Age of Earth and Fossils

_____________ ________ indicates that the earth is
approximately 4.5 billion years old, plenty of time for evolution to
occur.

Darwin didn’t have enough __________ evidence to show the
evolution of a modern species from their ancestors. Recent
discoveries show the evolution of whales from ancient land
mammals.
Comparing Anatomy and Embryology

Darwin suggested that animals with similar structures evolved
from a ____________ _____________. The structures shared by a
related species that have been inherited from a common ancestor
are called __________________ structures.

Similarities and differences among homologous structures
indicate how _______________ these species shared a common
ancestor.
Draw the diagram of Figure 16-14
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
____________ ___________ are inherited from
ancestors but have lost much of their function if
not all their function. Dolphins have hipbones that of are no use
yet they may have played a role in their locomotion while on land.

Embryological development of vertebrates is very similar,
providing evidence that organisms have descended from a
____________ _____________.
Genetics and Molecular Biology

Our advancements in genetics indicate that all living things share
the same ________ and ________ to carry information from one
generation to the next. Genetics provides some of the strongest
supporting evidence of evolution.

_____________ molecules show structural and chemical
similarities at the molecular level. An example is cytochrome c, a
protein which functions in cellular respiration for all types of cells.
Testing Natural Selection
Use the area below to explain how recent research on the
Galapagos finches has supported Darwin’s theory of evolution.
This can be done in point form.
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