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 Definition: ________________________________________________________
o Observations lead to hypotheses, hypotheses lead to experiments, many
experiments lead to a theory.
o Can be modified, or even proven false
o Considered successful if it can be used to make measurable, testable
predictions that are correct
EX: Cell Theory
 Definition: ________________________________________________________
o Observations lead to a mathematical model, model is used to describe
events, measurements of events are used to reinforce model
o Always the same outcomes under the same conditions
o Can be modified, or even proven false
EX: Newton’s Laws of Motion, Law of Gravity
Biology deals with theories, not laws. Physics and Chemistry deal more with laws
then theories.
The Theory of Evolution:
A collection of facts, observations, hypotheses and explanations about how
Evolution: ________________________________________________________
Introduction and Terminology
Variation and Species:
 A species is an _______________________ population of organisms that can
reproduce __________________, _________________________ offspring
Variation is the ____________________________________________________
o EX: hair color; fur color; height; size
Variations can be physical, behavioral, or chemical
o EX:
 Physical - color, size
 Behavioral - mating rituals, diet
 Chemical - blood type, hormone levels
Variation creates a population w/ ____________________________________
and these traits determine the _________________________________________
in an environment.
________________________ and _____________________________________
(during crossing over of meiosis) cause variations with in populations
o Mutations can be positive, negative, or have no effect for an organism
 Positive mutations help the organism to survive allowing them to
__________________________ and pass that positive mutation on
to their offspring
 ___________________________________ are inherited traits that increase an
organism’s (or population’s) chances of survival in an environment
There are many types of adaptations that help organisms to survive better
Adaptations allow populations to become suited to a specific niche
o Niche is a _________________________________________________
___________________________________________. A niche includes:
 Habitat, diet, raising offspring, and predation
Jean Baptiste LaMarck
A French naturalist that did his work prior to Charles Darwin and Alfred R.
Suggested evolution as a ________________________________________ to
explain relationships of fossils to current organisms
o Among the first scientist to recognize that living things changed over time
LaMarck’s Theory of Acquired Characters had 3 main ideas:
1. Desire to Change: __________________________________________________
a. EX: Giraffes – according to LaMarck, giraffes have long necks because
they stretched their necks to reach the leaves that were higher on trees
2. Use and disuse: most used body structures ____________________________ and
the unused structures ____________________________________
a. EX: Giraffes – used their necks for reaching leaves, so their necks
continued to develop and get longer
3. Passing on of ______________________________ traits
a. EX: Giraffes – giraffes that stretched their necks passed on their stretched
IMPORTANT: LaMarck was incorrect, but he is still credited with being one of the
first people to devise a theory of evolution and adaptation!
Charles Darwin
A little history
o Boat he traveled on: ____________________________________
o Islands he spent a lot of time on: ___________________________
o Animals he focused on: __________________________________
o Book he wrote: _____________________________________
Natural Selection
Natural Selection: ___________________________________________________
o Some part of the organism's environment selects the traits
o Organisms with traits beneficial in the environment survive, reproduce and
pass those traits on to their offspring
 Which would be more likely to survive in a muddy pond, a bright
red frog or a brown frog? Why?
Main Points of Natural Selection
1. Living things ______________________________________________
 More offspring are produced than survive
o EX: frogs produce hundreds of eggs, but only a few develop into adult
2. There is _____________________________________ in traits among individuals
 Each living thing does not appear exactly like all the others
3. There is a struggle to __________________________, _____________ for resources
 There are more living things than there are resources
 Organisms compete with each other for resources and survival
4. _______________________________________________ is always taking place
o Individuals with traits that increase fitness have more offspring than those
without those traits
 Fitness: ______________________________________________
Individuals that survive and reproduce will pass their traits to their offspring, so
the traits of better adapted individuals will increase in proportion in the population
over time.
***Remember: New traits arise from mutations, or changes in DNA***
The Development of New Species
 Species: __________________________________________________________
Speciation: ________________________________________________________
o Speciation commonly occurs when members of a species have been
Separation of Species
New species may form due to:
o _______________________________________________ (rivers, oceans,
mountains, glaciers, lava flows)
Animals of the same species find themselves living in different
This causes ________________________________________, or
the separation of population so that species cannot interbreed
Natural Selection will work separately on each group
With different gene pools, different adaptations can appear
in each group
This increases the differences between the groups and their
gene pools become more dissimilar, eventually creating 2
different species
EX: species of finches on Galapagos Islands
Each species of finch had a different beak shape to suit the
food on their island
Evidence of Evolution
 Fossils are _________________________________________________________
Fossils are found in ___________________________________ rocks
o Position of fossils in rock layers reveal the relative age of the organism
Fossil record: ______________________________________________________
o Some fossils are not preserved well and some organisms do not leave
fossils at all - this accounts for gaps in the fossil record
o The fossil record provides information about:
 The _____________ of the Earth
___________________ in Earth
Evolution of _______________________
Earth’s _____________________ and ______________________
Homologous Structures (aka comparative anatomy)
Homologous Structures are traits that have _______________________ structures
but _______________________________ functions in different species
o EX: Flippers, hands, bat wings, and bird wings all function differently, yet
are made up of the same group of bones!
Certain anatomical similarities among species support evolutionary history
Vestigial Structures
Vestigial Structures are structures that are _____________________________
and often ___________________________
o Historical remnants of structures important in ancestors
EX: whales of today lack hindlimbs, yet have vestiges of the pelvis
and leg bones of their 4-footed terrestrial ancestors
Comparative Embryology
Comparison of structures that appear during the development of different
Closely related organisms often have similar stages in embryonic development
Evidence that vertebrates evolved from a ________________________________
o All vertebrates (fishes, frogs, snakes, birds, apes) have gill pouches/slits
on sides of throat during embryonic stage
Comparative Biochemistry (molecular biology)
Common genetic code shared by all species
Evolutionary relationships among species leave signs in DNA/proteins
(genes/gene products)
If 2 species have genes/proteins with sequences that match closely, sequences
must have been copied from __________________________________________
o _______________________________________is a protein used in
respiration by all organisms
o _____________________ is an energy molecule for all living things
o All organisms use _________ and __________ to transmit genetic info
Biogeography is the study of __________________________________________
o Suggested to Darwin that organisms evolved from ancestral forms
Galapagos animals resembled species of South American mainland
more than animals on similar but distant islands
o Tropical animals of South America more closely related to species in
South American deserts than to species in African tropics