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Chapter 15.1
Natural Selection and Evidence for Evolution Day1
I.


What is evolution?
changes in living organisms_____________________________
explains how modern organisms have descended from ancient organisms
Why is evolution
considered a theory and
not a law or hypothesis?
II.

Evolution explains unity and diversity
Only evolution explains both
 ___________________________
 similarities between all living things
 ___________________________
 wide variety of different creatures on Earth
In your own words what
is diversity?
III. Charles Darwin
 Proposed a way how evolution works
 How did creatures change over time?
 by _____________________________
 Collected a lot of evidence to support his ideas
 1809-1882
 British naturalist
IV. Voyage of the HMS Beagle
 Invited to travel around the world
 Stopped in __________________________________
 500 miles off coast of Ecuador
 Darwin found a lot of unique species
 Darwin found a lot of fossils
Evidence that creatures have changed over time
 Different shells on tortoises on different islands
V. Darwin’s Finches = Divergent Evolution (Species isolated on different islands blocked the
gene flow between finches)
 ____________________in beaks
 differences in beaks in the original flock
 adaptations to foods available on islands
 _____________________ for most fit
 over many generations, the finches were selected for specific beaks & behaviors
 offspring __________________successful traits
 accumulation of winning traits: both beaks & behaviors
 _____________________-the process by which new species arise
 separate into different species
VI. Early ideas of evolution: NOT VALID
 LaMarck
 evolution by ______________________
 creatures developed traits during their lifetime
 give those traits to their offspring
 example: in reaching higher
leaves giraffes stretch their necks & give the__________ longer neck to offspring
 not accepted as valid
VII. Darwin’s view on evolution: VALID
 giraffes that already have long necks survive better
 leave more offspring who________________ their long necks
 ____________________
 selection & survival
 reproduction & inheritance of more _________________
What is Gene Flow?
In your own words, what
is an adaptation?
Why is LaMarck’s idea of
evolution NOT valid?
VIII. 5 principles of natural selection
1. ______________________ variation exists in populations (we are all different!)
2. ______________________ of offspring
 more offspring are born than the environment can support
3. _____________________
 for food, mates, nesting sites, escape predators
4. differential __________________
 successful traits = adaptations
5. differential __________________
 adaptations become more common in population
 adaptations: the traits that help an organism fit the environment better to
__________________ and _______________________
IX. Darwin Concluded
 Each species has descended, with changes, from other species over time.
 Darwin called this _______________________________________
OR
 Evolution: ____________________________
X. Evidence supporting evolution
 __________________________
 shows change over time
 __________________________
 comparing body structures
 homology & vestigial structures
 embryology & development
 __________________________
 comparing protein & DNA sequences
 __________________________
 human caused evolution
1.
Which of the following evolutionary biologists would agree with the statement below?
“Due to several sever winters; the available food source for white tail deer is not located
close to the ground. As a result, the deer must stretch their necks to reach the food, and this
stretching will result in longer necks and both the deer and their offspring in future
generations.”
A. Charles Darwin
B. Gregor Mendel
C. Jean-Baptiste Lamark
D. Hugo deVries
2.
All of the following statements describe natural selection EXCEPT
A. It was described in a theory by Charles Darwin
B. It acts on phenotypes in a population
C. It is sometimes describe as survival of the fittest
D. It selects traits that decrease a species’ fitness
Describe an adaptation
that would positively
impact the survival of that
species.
Describe an adaptation
that would negatively
impact the survival of that
species.
In your own words,
describe descent with
modification.
XI. Fossil Record
 Layers of rock contain fossils
 new layers cover older ones
 creates a record over time
 fossils show a series of organisms have lived on Earth over a long period of time
Law of _________________
The deeper you dig, the farther back in time you go
The bottom layer is the oldest
Anatomical Records
Animals with different structures on the surface, but when you look under the skin…
It tells an evolutionary story of common ancestors
The same bones under the skin
 limbs that perform ______________________ yet are built from the same bones
 HOMOLOGOUS STRUCTURES
 Structures that come from the same origin
 Forelimbs of human, cats, whales, & bats
 same structure on the inside
 same development in embryo
 different functions on the outside
 evidence of __________________ancestor
Draw and explain the
Law of Superposition
XII.



ANALOGOUS STRUCTURES
 look similar on the outside
 same function
 different structures on the inside
 different origin
 no evolutionary__________________
 Convergent evolution: the independent
evolution of similar features in unrelated
species.
 Example: aquatic organisms
Dolphins: aquatic mammal
Fish: aquatic vertebrate
both adapted to life in the sea not closely related
 VESTIGIAL STRUCTURES
 Structures on modern animals that have ___________________
 remains of ____________that were _______ _in ancestors
________________of change over time
 some snakes & whales have pelvis bones
& leg bones of walking ancestors
 eyes on blind cave fish
 human tail bone
 COMPARATIVE EMBRYOLOGY
 Development of embryo tells an
evolutionary story
 similar structures during development
What do the following
prefixes mean?
homo- =
-logous =
How are analogous
structures an example of
convergent evolution?
XIII. Molecular (DNA) Records
 Comparing DNA & protein structure
 Everyone uses the same genetic code! (DNA)
 to do this we compare amino acid sequences
 From this we can build family trees
 Phylogeny! Closely related species are branches on the tree — coming from a
common ancestor
gln
Horse
pro
phe
thr
thr
ala
gln
glu
phe
ser
thr
asp
glu
phe
ser
thr
asp
ala
phe
ser
thr
asp
Chicken
XIV. Artificial Selection
gln
Tuna
 How do we know natural selection can change a population?
 we can recreate a similar process
gln
Frog
 “evolution by __________________________”
 Unexpected consequences of artificial selection
 Pesticide resistance
 Antibiotic resistance
 Spray the field, but…
 insecticide didn’t kill all individuals
 variation within population
 resistant survivors____________________________
 resistance is___________________________
 insecticide becomes ____________________________
 Genetic drift examines the genes in a specie population and has a role in
determining whether a given individual survives and reproduces
Time to Practice…
1. Selective breeding has been used for thousands of years to
a. develop bacteria that produce human insulin
b. clone desirable plant varieties
c. develop viruses that protect against diseases
d. produce new varieties of domestic animals
2. Which characteristic is necessary for natural selection to occur in a species?
a. stability
b. variation
c. complex cellular organization
d. a very low mutation rate
3. The evolutionary pathways of several species are represented in the diagram below.
Which species was best adapted for survival in changing environmental conditions?
a. A
b. E
c. K
d. L
4. Which group would most likely have the greatest survival success during a long period of
environmental changes?
a. a small population of rabbits living in a field of grass
b. a large population of red ants living in a forest
c. an endangered population of polar bears living near an iceberg
d. one species of bird that nest only in sugar maple trees
Using the table below,
determine which
organisms are most
closely related.
What is genetic drift?
When you a person is
prescribed antibiotics why
is it extremely important
for them to finish the
entire cycle of antibiotics
as prescribed?