Chapter 6
Name: _____________________________ Period: _____
Darwin’ s Theory
•_______________________ –a British _______________________ who developed the theory of _______________________ by _______________________ _______________________
•He observed: diversity of ______________________________ , the remains of _______________________ _______________________, and the _______________________of organisms on the _______________________ _______________________
Diversity
•Darwin noticed the tremendous _______________________ of living things
•Scientists have _______________________ more than 1.7
million
_______________________ of organisms on _______________________
•Species –____________________________________________________ _______________________________________________________________ ______________________________________________________________
Fossils
•Fossils –_______________________________________________________ __________________________________________________________________
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Fossils puzzled Darwin as he noticed that the _______________
_____________ he found were ___________________________ than the _______________________ that he was used to. o What kind of fossilized animals do you think Darwin was
observing? _________________________________
Galapagos Organisms
•Darwin noticed that the __________________ __________________ were __________________ __________________ from the __________________ he was used to in __________________
•The organisms even __________________ a __________________ from __________________ Galapagos Islands
–Example: ________________________________________ Adaptations
•Adaptation –___________________________________________________ ________________________________________________________________ ________________________________________________________________
Evolution •Darwin’ s __________________ on the Galapagos Islands intrigued him for __________________
•Darwin reasoned that the __________________ and _________________ that arrived on the Galapagos Islands faced __________________ __________________ that were very __________________ from the __________________ 2
•He hypothesized that the species __________________ __________________ over many __________________ and became better __________________ to the _______ conditions
•This gradual change in a __________________ over time is called __________________
•Darwin’ s __________________ concluded that the organisms on the Galapagos Islands ______________________
•However, he __________________________________ it happened •He studied __________________ __________________ to see if that explained things
Natural Selection
•Darwin tried to explain evolution through __________________ __________________
•Natural selection –the process by which __________________ that are __________________ __________________ to their environment are _____________ likely to survive and reproduce than members of the _______________ ______________________
Factors that affect natural selection
•1. ___________________________ –most species produce far more offspring than can possibly survive
•2. ___________________________ –any difference between individuals of the same species
•3. ___________________________ –members of the same species must compete for food and other resources to survive 3
•4. ____________________________ –organisms with “selected”helpful traits become parents of the next generation
•5. _____________________________ –a change in the environment can affect an organism’ s ability to survive, therefore leading to selection
•6. ______________________________ –only traits that are inherited can be acted upon by natural selection
Evidence of Evolution
•__________________ , patterns of early __________________, and __________________ body structure all provide __________________ that organisms have __________________ over time.
Fossils
•__________________ showed us that organisms that lived in the past were __________________ __________________ than the organisms alive today
Where are fossils found?
•Most are found in ______________________________ ______________ –Hardened layers of sediments __________________, __________________, __________________ or __________________)
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Early Development
•By comparing what organisms __________________ ____________
in
their __________________ development __________________ scientists could conclude how __________________ organisms are ______________
•See textbook page 183 for example Body Structure •Scientists compared __________________ __________________ of living species and concluded that some organisms __________________ from a __________________ __________________
•_____________________________________________ –similar structures that related species have __________________ from a common ancestor
Species Relationships
•Similarities in _______ , protein __________________, __________________, early development, and body structure have been used to determine the __________________ __________________ among species
Branching Trees
•_________________ that show how scientists think __________________ groups of organism are __________________
•See textbook pg. 186 to see an example of how raccoons, lesser pandas, giant pandas, and bears may be related!!!
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How do we get new species?
•A _________ species can form when a group of individuals ___________ __________________ from the rest of its species __________________ enough to __________________ different traits
–Example: Kaibab squirrel versus Abert’ s squirrel How do fossils form? –1. _____________________________________ –2. Layers of __________________ cover the animal’ s _______________ –3. _______________ go by and the sediments harden to become rock –4. The animal is now _______________________ as a fossil –5. The rock __________________ and the fossil gets ________________
Types of Fossils •
1. ___________________________________ =A fossil that is __________ when ________________ _________________ all or part of an organism
• 2. ______________ = A type of fossil that is formed when a _______________ or other hard part of an organism _______________, leaving an _____________ ________________ in the shape of the part
• 3. ______________ = A type of fossil that forms when a ____________ becomes filled in with ____________________ that then ____________
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Aging a fossil
•Scientists can determine a fossil’ s age using: –1. __________________________ –determines which of two fossils is _____________ (does not tell __________________ _______ )
–2. __________________________ –determines the ____________ age of a fossil using the ______________ of a _____________________ __________________ (usually Carbon–14)
Half - life •This is the time it takes for _____________ of the __________________ in a radioactive element to ______________ in a sample
•Scientists compare the amount of a radioactive element in a sample to the _______________ of the element into which it _____________ down.
Fossil Record
•It is the _______________ of ____________ that scientists have collected •It has revealed how __________________ of the species preserved as fossils are now __________________
•_________________ = No members of a species are still alive •Helped scientists create the __________________ ____________ __________________ (see page 194–195)
•It also led to two unanswered questions: –1. ____________________________________________________________ –2. ____________________________________________________________ 7
Mass Extinctions •Occurs when __________________ types of organisms become __________________ at the _______ time.
•The last mass extinction occurred about _________________________ ago when the __________________ were wiped out
•Scientists hypothesize that __________________ __________________ changes may be responsible
Gradualism
•A theory that proposes that evolution occurs _____________________ •_______ changes in a species __________________ up to ______________ changes over very ____________ periods of time
Punctuated Equilibrium •A theory that accounts for the __________________ in the fossil record •It says that species evolve ________________ during _________________ short periods
•These periods of __________________ change are __________________ by long periods of __________________ or _______ change
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