Download Chapter 15 * Darwin*s Theory of Evolution

Chapter 15
Darwin’s Theory of Evolution
15-1 The puzzle of Life’s diversity
• Evolution = _________________________________________________________
• Theory = ___________________________________________________________
* A scientific theory has been accepted:
- explains a wide variety of data and observations
-
can be used ____________________________________
- They are not absolute, ______________________________________
and can be changed as the world view changes.
Darwin’s Theory of Evolution
• Voyage of the H.M.S. Beagle; ______________________________
• Observed finches, tortoises, and other animals on the _________________________
• Published _______________________________________________________
• Proposed “________________________________________________________”
15-2 Ideas that shaped Darwin’s Thinking
Other theories at the time …
• All life was created in just a _________________________________ and has not changed
• Hutton
- the Earth is changing & __________________________________________
• Lyell
- If Earth is changing - _______________________________________
Lamarck’s Theory of Evolution
• Inheritance of ______________________________________ (1809)
o Believed that organisms had a “_______________________________” that drove variation
o Selective ________________________________
Ex. Giraffe
• Giraffes had short necks, and “__________________” to reach high branches
• Over time they were able to _________________________________ to reach branches
• This new, _________________________________ was passed onto offspring
15-3 Darwin Presents his Case
Back to Darwin’s Theory …
What is Natural Selection??
• Based on the existence of ___________________________________
-
differences between ___________________________
some cows produce more milk
some plants produce larger fruit
• Farmers already used ___________________________________ to get the best livestock & crops
So now we have the idea that _____________________ does this also!
Variation between Organisms
• ____________________________________ is the differences between organisms’ _______________
• ______________________________________
- a ________________ that makes a living thing able to
________________________ in its environment/surroundings
- This makes it an ______________________________
- Advantage is they live longer!
•_______________________________________ = struggle for existence
Fitness
The advantage of living longer is ______________________________________________________
During reproduction, the organism’s _____________________ can be passed on to the offspring
The _______________________________ is thus able to be passed on to the ___________________
“Survival of the Fittest”
• Organisms with the most
pass on their traits
– The
determine
•
Example: the color of the soil determines which color fur is an advantage for mice
•
Called
–
Nature chooses!
–
Compare to
, when humans choose what
traits they desire and have those organisms reproduce
»
Ex:
Mice in the Desert
When the soil is a dark color
-
The mice with light fur
__________________________________________________
- The mice with dark fur _____________________________________
The mice with dark fur blend in well and are eaten less = _______________________
• If the soil changes from a lot of rain and is now a light color …
-
The mice with dark fur are now easier to see and eaten more often by owls
-
Now the mice with light fur blend in and have an ___________________
Descent with Modification
• The structural and biochemical _____________________________ among living organisms are best
explained by Darwin’s conclusion:
- Living organisms ___________________ through gradual modification of ______________
forms = descent from __________________________________________
• Without ____________________________________, there’s little chance that organisms would
have all these similarities
MCAS Essay
The graph below relates the number of gray squirrels in a
small population to their coat colors.
o This squirrel population has been separated from other
squirrel populations by a new highway and several
construction sites. The main predators of these squirrels
are cats and hawks.
a. Assume that dark gray squirrels are very visible in
this new environment. What is likely to happen to
the distribution of coat color in this squirrel
population over several generations? Sketch a graph
in your Student Answer Booklet to show the
predicted distribution, and explain your answer.
b. Assume that dark gray squirrels are very visible
on the ground, and light gray squirrels are very
visible in the trees. Explain what is likely to happen
to the distribution of coat color in the squirrel
population over several generations. You may
sketch a graph in your Student Answer Booklet as
part of your explanation.
Conditions needed for Evolution
1. __________________________________________________________________
a. species will not become extinct if some do not survive to reproduce
2. __________________________________________________________________
3. __________________________________________________________________
a. Competition within a niche
b. Niche: a specific role (job) of an organism within a community
4. __________________________________________________________________
Where is the EVIDENCE??
Evidence for Evolution
• __________________________________________
- Originally thought it was 240 million years old
- Now it is known to be 4.5 billion years old
• __________________________________________
- Fossil - ____________________________ of something once living
- Found trapped in ice, sap, or sedimentary rock
• ___________________________________________
- Organisms that have a __________________________ develop in the same
manner & thus often look alike
• ____________________________________________
- Similar DNA sequences
Age of the Earth
° Layers of rocks represent time
-
_______________rocks on bottom, newer on top
° ____________________________ - a fossil found at bottom is older than one found
at the top
° ____________________________ - certain radioactive elements decay at a
Predictable rate (_________________)
• ___________ of the radioactive element decays into a different element in
X number of years
• ____________________ Carbon-14 decays to nitrogen in 5770 years
• If you started with 1 gram – after 5770 yrs. You’ll have ____________
• After 11,549 yrs. You’ll have _______________
Geologic Time Scale
Fossil Record
° Collection of fossils put together to represent the history of
___________________
° Problem with this record: ____________
- some living things were not preserved because they
did not have “bony” parts
- some living things did not live in area where fossils
were made
° Need _______________ to make fossils (near water)
Comparative Anatomy
° Early Development
• ___________________ - organism at early stage of development (before birth)
° All _______________________ begin to develop the same way
- Any major changes here would have caused so much change the organism would not
survive
° Homologous Structures
• Structures that develop from
______________________, but into different uses
° Analogous Structures
• An appendage has the ______________________
but a __________________ internal structure
Example: Wings are for flying, but a bird wing
has bones & a butterfly wing doesn’t
° Vestigial Structures
• A trace of a structure that is no longer useful
Examples: Human tailbone and Whale hips
Molecular Biology
• All organisms have ___________ made of the same nucleotides
• The more similar two organisms’ DNA is, the more likely they share a _____________
- Chimps & gorillas are 97.9% the same
- Humans & chimps are 98.4% the same
• Maternal Mitochondrial DNA
• Y chromosome
MCAS Essay
The illustrations below show a
South American finch and
some of the species of finches
found on the Galápagos
Islands. The map shows the
relationship of the Galápagos
Islands to the west coast of
South America.
o There are 13 species of
finches found on the
Galápagos Islands. These
finches have a wide
variety of food sources and
beak shapes. There is one
genetically similar species
of finch found on the
South American mainland.
This finch eats small
seeds.
o
Use the map and the bird
illustrations to identify and
explain two ways that these finches provide evidence that supports the theory of evolution.
Chapter 16
Evolution of Populations
16-1 Genes and Variation
●
●
●
●
Darwin did not know about ___________________________
How did traits get inherited?
How did variation appear?
1930’s – scientists connected Darwin & Mendel’s works
Variation & Gene Pools
● Population = ____________________________________________________________
● When you combine all the genes they share it is called the _____________________
- Ex. Snakes have no legs, scales covering their bodies, long tongues, different
Color patterns
● How common the gene is, is it’s ________________________________________
allele for
brown fur
allele for
black fur
Frequency of the allele for
brown fur is
=____________________
Frequency of the allele for black
fur is =
_____________________
Evolution is …
● Any change in the ______________________________ of alleles in a _________________
Ex. Mice (above)
● 40% frequency of ______
● 60% frequency of ______
● If this changes to 30% B – the population is _____________________________!!
Where does all of this VARIATION come from?
1. _____________________________
● _____________________________ are helpful ______________
● ____________________ come from ______________________
-
New traits come from new genes
● New ___________________ come from _____________________________
-
Mutation = ____________________________________
● Mutations can be
GOOD, BAD, NO EFFECT
2. _______________________________________
● _____________________________
From __________ pairs you can get _____________ million combinations of genes!!
16-3 The Process of Speciation
The Result of Evolution …
● New species are formed
● ______________________________
-
smallest group of classification
able to produce _____________________ offspring
● ___________________ = able to make eggs or sperm
● ___________________ = NOT able to reproduce
● A new species is defined when two ___________________________ are no longer able
to produce _____________________ offspring
-
result of ____________________ adding up
Ex. A labradoodle is __________________________
● the poodle & Labrador are the _______________________ species
A Mule is ________________________
● the horse and donkey are ________________ the same species
How do new species form?
● Result of ____________ species becoming SO different from the original it is now a 2nd species
Ex. Adaptation lab – all started with a hand, now you have 5 different species
- the tweezers, the fork, the small spoon, the large spoon & the chopsticks
Ex. Finches on Galapagos Islands
How speciation happens …
1. ______________________________________
● Few members of main population are ______________________ to a new location
(ie: island)
2. ______________________________________
● Now no longer able to “mingle” with original population due to geographic features
(canyons, oceans, rivers, etc.)
3. __________________________________________
● __________________________
● Gene shuffling from sexual reproduction
4. ______________________________________ - when members of a species can no longer
reproduce for various reasons
1. _____________________________ (courtship) such as different mating calls or dances
2. _____________________________ (place) such as a river, island or mountain getting in the
way
3. ___________________________ (time) in terms of when the population is ready to mate
5. _________________________________________
● __________________________________
● The new species are now competing for the same niche
- Remember only ONE species can occupy a niche
6. ___________________________________________
● Creates diversity of life
17-4 Patterns of Evolution
1. Mass Extinction
● A ____________________________________
- Usually due to the _______________________ suddenly changing
- 99% of all life now extinct
- 5 major mass extinction events
- Ex. Dinosaurs
2. ___________________________________ (aka divergent evolution)
● This is most common form, such as Darwin’s finches
● An original group of species evolves into ___________________ different species best
suited to different environments
3. ______________________________________
● Unrelated species (____________________________) that look alike
Ex. Swimming species like fish, sharks, penguins & whales
4. _______________________________________
● One species evolves in response to the ___________________ in another species
● Often a _____________________________ relationship or insects & pollination
● ________________________ (termites)
5. _______________________________________
● Random changes in ____________________ frequencies
-
Can be pure chance or sometimes a natural disaster/disease
● Evolution occurs in the absence of _________________________________
Ex. Rhinoceros – some have one horn, others have two – no advantage
6. __________________________________
● Changes occur slowly and gradually
7. ______________________________________
● Long periods of NO change with brief periods of sudden change
Ex. Peppered moths
Or no Evolution at all …
● _______________________________________________________
● Some species are well adapted to live in their environment and haven’t changed for hundreds of millions of
years
● They are called ________________________________
Ex. Horseshoe crab, coelacanth, frilled shark