Download Aim 44: Darwin`s Theory of Natural Selection I. Lamarck`s

Unit 8: Evolution
Name:
Aim 44: Darwin’s Theory of Natural Selection
I.
Date:
Lamarck’s Competing Theory of Evolution
Two scientists, Jean-Baptiste Lamarck and Charles Darwin are often noted for their studies of Evolution and
how traits are inherited.
What did Lamarck believe? Why was it unaccepted?
•
Believed organisms change because they “___________________” to adapt to a changing environment
•
Inheritance of Acquired Characteristics:
states that changes __________________ by an
organism during its lifetime will be passed onto its
offspring.
o
Ex: Giraffes have long necks because they
stretched their necks throughout their lifetime
to reach the leaves on top of trees, so their
offspring and later generations will inherit
these long necks.
His theory was disproven through the discovery of ____________ and the mechanisms of inheritance.
•
II.
Charles Darwin’s Theory of Evolution
Observation from the
Galapagos Islands
Explanation for the
differences in beaks between
all of the finches
What other process did
Darwin relate his findings to?
Observed that one type of bird (a finch) lived on each island, however every island
consisted of a bird with a different ______________.
Every finch had a beak that was _________________ for the environment and the type of
food available on each island.
Selective breeding or __________________________________, the practice used by
breeders to create offspring with the most desirable traits so those traits will get passed on
to future generations.
In any environment, an individual may be born with a characteristic that gives it an
________________________ over other members of the species, allowing them to
Darwin’s conclusion based on
his findings
survive, reproduce and pass this advantageous trait to their offspring. Overtime, this
advantageous trait will become ____________________________ with each generation.
If a characteristic _______________ an individual’s chance of survival, this trait will
_________________ over time. He called this process ___________________________
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III.
Natural Selection:
The ________________________ by which individuals best ___________________ to a specific environment
will ______________________, ____________________ and _______________ their genetic information to
future generations
If the following conditions occur, then natural selection and evolution are taking place
Within a population there are _______________ offspring produced in each
1) Overproduction
generation than can possibly ____________________. Not all offspring can
survive because of _______________________ resources in the environment.
This leads to competition.
The ____________________ resources such as food, water, mates and space
2) Struggle for
Survival
(Competition)
available to a population, are ___________________. Because there are more
organisms produced in each generation than can survive, there must be
_____________________ among them for the resources needed for survival. •
Members of a species are all ________________________ from each other.
•
These variations among members of the population make some of them
better _____________________ to the environment than others. Due to
3) Variation
competition, the best-adapted individuals are more likely to
___________________.
•
___________________ is a measure of how well a trait or variation helps
an organism to survive & reproduce in its environment. What is considered
“_______” in one environment may be “___________” in another.
•
Individuals with helpful variations will survive, reproduce & __________
these adaptations to their offspring.
4) Reproduction
•
Individuals with harmful variations _________________ within the
population and _______________ pass their traits to future generations.
•
Eventually, nearly all the individuals in the population will have the
_______________________ trait. This change in the characteristics present
in population over time is __________________________
NO ONE is CHOOSING who survives and who doesn’t. It is the result of the conditions of the organism’s
ENVIRONMENT. The POPULATION will EVOLVE over time, NOT an INDIVIDUAL because each individual is
born with genetic information that may or may not help them survive and reproduce. An individual’s genes DO NOT
adapt to a changing environment.
2
a) How would Darwin explain why the giraffes evolved to have larger necks?
b) How does natural selection differ from artificial selection? (indicate who is doing the “choosing”)
c) Circle the best answer in parenthesis: Variations that are beneficial to an organism (increase/decrease) chances
of survival and (increase/decrease) in frequency in the population. Variations that are harmful to an organism
(increase/decrease) chances of survival and (increase/decrease) in frequency in the population
d) The environment is constantly changing. In order to survive in a changing environment, what does this tell us about
species here on Earth?
IV.
Modern Theory of Evolution
What was Darwin
unaware of when he
created his theory of
evolution?
What does the modern
theory of evolution
explain?
How do genetic
variations arise?
______________ caused these variations and _____________ these variations were inherited
by future generations.
Due to the knowledge we gained about DNAàRNAàProteins, the modern theory helps
support Darwin’s theory by offering an explanation as to how new traits (variations) can arise
1. Shuffling of ______________ during ________________ (genetic recombination)
2. _______________________________
3. _________________________ in an organism’s ________________________
What are some things that WOULD NOT lead to evolution and would decrease the survival rate of a species?
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V.
Modern Day Examples of Natural Selection
1. Peppered Moths
•
Increased industrialization resulted in smoke and
soot turning all the plants and rocks black.
•
Moths before industrial revolution = ____________
•
Moths after industrial revolution= ______________
•
Darkly colored moths were
better in this new environment, increasing their
____________________.
•
The dark coloration gave the moths a selective advantage. Overtime, the dark colored gene _________________
in the population and the light colored gene ______________ in the population
2. Antibiotic/Drug Resistance
•
Some bacteria may have a _______________________ resistance
(due to a mutation) to antibiotics (they will not die). When bacteria are
exposed to antibiotics, susceptible (non-resistant) bacteria will ________
and the resistant bacteria will _______________
•
The resistant bacteria survive, reproduce and ___________________
(quickly) and produce more _____________________ bacteria
•
The antibiotic soon becomes _______________________ in killing that
bacteria
•
This is why we constantly need to develop new antibiotics and drugs
Because bacteria and viruses evolve ______________________ to
antibiotics and other drugs very quickly.
3.
D) Direct observation: Humans see evolution happen
Pesticide Resistance
1. Bacteria evolve resistance to antibiotics. DO N
• __________ is a type of pesticide used to 2.
kill _________________
Insects evolve resistance to pesticides. DO NO
•
DDT resistant mosquitoes are great in
number because a genetic difference or a
______________________ allowed some
mosquitos to _________________ DDT
use, reproduce and pass their
____________________ onto future
generations (similar to antibiotic
resistance)
3. Artificial selection / Selective breeding alters
a
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but with humans choosing the best traits inste