Evolution
Evolution – process through which species _____________ ___________ ___________
 The process by which ________________ ______________ (________________) have
descended from ancient organisms (________________)
 __________ _________ ______ ___________ was the first scientist to propose a model of how
life evolves
Lamarck’s theory of acquired characteristics
 Lamarck said organisms ________________ traits by using their bodies in new ways
 These new ________________ were passed to offspring
 Lamarck was ______________ to provide an evidence to support his ideas
Charles Darwin (1809-1882) sailed around the world (1831-1836)
What did Darwin’s travels reveal?
 The _____________ of living species was far greater than anyone had previously known!!
 ______________ made observations on his voyage that later became the foundation for his
_______________ ________ ______________ _____ ____________ _____________
How did the finches differ among the islands of the Galapagos?
 Darwin noticed _________________ between the finches on the island and those of the nearby
mainland
 Each island had its own type of finch that were clearly different from the other islands
 Darwin specifically noticed the differences in the shape of their ___________ and in the
__________ they ate
Darwin Thoughts
 Darwin wondered why the __________ finches were different from the _____________ finches
 He _______________ that perhaps some finches were blown to the island by a storm and over
time the finches that survived __________ to different ways of living on the islands
 Darwin looked to selective breeding for clues
 ____________ ____________ - humans, not nature, select which traits will be passed along to the
next generation (a farmer breeds only his best livestock)
 Darwin proposed that ______________ works somewhat in the same way… organisms that are
__________ ________________ are able to ______________ and _________________
 So they are somewhat “selected” by nature and pass their helpful trait to their offspring
 ______________ _______________ – members of a species that are best suited to their
environment survive and reproduce at a higher rate than other members of the species
 Mutation – ________________ _________ ___________ _______________
- mutation causes __________ ___________
-mutation is ________________
-mutation is _______________
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-Beneficial mutations allow organisms to _______________ and ______________ at a
higher rate
Natural Selection Wins!
 In 1859, Darwin published his results in his book called On the Origin of Species by Means of
Natural Selection
 Darwin theorized that evolution occurs through a process he called natural selection (survival of
the fittest)
Natural Selection in 4 Steps
1. ____________________-each species produces more offspring than will survive to maturity
2. _______________ ________________ - the individuals in a population are slightly different from
one another. Some traits increase the chances that the individual will survive and reproduce
3. _____________ _________ _____________ - a natural environment does not have enough food,
water, and other resources to support all the individuals born. In addition, many are killed by other
organisms
4. ________________ ________________ - the individuals that are well adapted to their
environment are more likely to survive and reproduce
Insecticide Resistance
 Insects quickly develop resistance to insecticides because they produce many offspring and
usually have short generation times
 ________________ _____________ - is the period between the birth of one generation and the
birth of the next generation
 In the 50 years that insecticides have been used, more than 500 species of insects have developed
resistance to certain insecticides
Formation of New Species
 _____________ _______________ can explain how a species can evolve into a new species.
 Over time, two populations can become so different that they can no longer interbreed. This
process is called _________________
3 Ways Speciation Can Occur
1. _______________ - a newly formed canyon, mountain range, or lake are a few ways that
populations can be divided
2. _________________ - if a population has been separated, the environment may also change. To
live the species must adapt to the new environment
3. _________________ - over thousands or millions of generations, the two groups of a population
may become so different that they can no longer interbreed. At this point, they are no longer the same
species
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Peppered Moths of Manchester
 Peppered moths spent most of their time resting on the bark of oak tree trunks. Most of the oak
trees in England were light brown, speckled with green
 Most of the __________________ ________________ at that time were light brown too
 Some dark ones around, but few.
 _________________ from _________________ _____________ stained London trees dark
brown
 Suddenly scientists noticed the population of ________________ _____________
_________________, and the __________________ __________________
__________________ ____________________
 Birds were the moths major _______________
 Birds can not see moths (prey) that blend in with tree trunks because they were
_________________
 The dark moths reproduced which increased the population of dark moths
 ____________________ - scientist who studied peppered moths
Evidence For Evolution
-______________ - are evidence of Evolution!
-_______________ - study of extinct life
- ________________ - remains of organisms preserved in the earth
Fossils
1. Fossils provide __________________ about the history of life
2. Fossils show how organisms have ______________ ___________ ______________
3. Fossil records are __________________ because most organisms die without leaving any trace!
Vestigial Structures
 _______________ ________________- body parts that are reduced in size and have no function
 Suggests that as the body part was no longer needed in the environment they were ___________
or _________________ in size
 Examples
 hip and leg bones in snakes
 pelvic and femur bones in whales suggest they once had back legs
-Older fossils are usually found in the ____________________ geologic layer!
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