Download Discuss with your table partner: What is speciation? How could

Discuss with your table partner:
What is speciation?
__________________________________
How could speciation occur?
_________________________________________
_________________________________________
_________________________________________
_________________________________________
Divergent Evolution
Divergent evolution is the accumulation of
differences which can lead to_________.
Homologous structures: similarities in
structures due to ________ ______________
but adapted to different functions.
Same origin
Examples of Homologous
Structures- passed down from a
common ancestor (Present
throughout the portion of the
branching tree of ancestry)
Vestigial structure:
A structure that is _____________ in function
or structure, but may have had function in
ancestor.
Examples:
_________
Ostrich wings
Star Nosed Mole:
Reduced sense of vision.
Convergent evolution:
Distantly related species evolve similar
adaptations, because they ___________
________________________________.
Example: Anteater and aardvark
In convergent evolution, trait is not shared by more closely
related species. The trait evolved independently in more
distantly related species because the of similarities in natural
selection pressure.
The similarities in structure on more distantly
related species, due to convergent evolution
are called analogous structures.
Example: wings of butterflies and bats
Discuss with your table partner the questions on
the next 3 slides.
Some snakes have skeletal remnants of legs.
What term describes this type of structure?
___________________________
Whales and other sea mammals have a similar
shape to fish, even though they are more closely
related to land mammals. What type of evolution is
this an example of?
____________________
What term describes the relationship between fish
and whale fins?
_____________________
The teeth of beavers and the tusks of elephant
stem from a common ancestor, but they are
adapted for different functions. What is this
an example of?
________________________
Coevolution
A process in which two (or more) species
reciprocally ___________________________.
Changes in the gene pool of one population
resulting changes in the gene pool of the
other species.
Coevolution can be a positive interaction,
resulting in a highly __________relationship.
Example: Specialist pollinators that only
pollinate one type of flower.
Advantage to pollinator- no
competition for food source.
Advantage to plant- _____________
_____________________________
Coevolution can be an adaptation to a negative
effect of another species.
“An evolutionary arms race”
Example: Increasing levels of toxins in one
species to avoid predation, with the predator
developing increasing tolerance to the toxin.
Fossils
Relative Dating:
Age is determined____________________________.
Law of Superposition:
For sedimentary rock
layers, if undisturbed
the youngest layers
will be on the _____.
Absolute Dating:
Radioisotope Dating
Half-Life: The amount of time that it takes
half of a radioactive sample to decay.
Half-life Comparisons
Radioisotope
Half-life
Berillyium-11
13.81 seconds
Iodine-131
8 days
Strontium-85
11 years
Tritium (Hydrogen-3)
12 years
Uranium-235
700 million years
Uranium-238
4.5 billion years
Determining amount of radioactive isotope remaining
Number of
Half-lives
Fraction
Remaining
Formula for
Fraction
Remaining
1
1/2
(1/2) 1
2
_____
____
3
_____
______
4
_____
____
Formula: N = No (1/2)t
t= number of half-lives
N = amount left N = original amount
Discuss with your table partner:
Strontium-23 has a half-live of 11 years.
If 1/16 of the original sample is left, how old is it?
__________________________
Carbon-14 has a half life of 5, 370 years. If a
sample is 16,110 years old, what fraction of
Carbon-14 would remain?
___________________________
Evidence for Evolutionary Relationships
Fossil Record: Transitional Fossils
Example: Archaeopteryx is a transitional fossil
between dinosaurs and birds.
Evidence for Evolutionary Relationships
Anatomical Comparisons: comparing body
structures.
Discuss with your table partner:
Why might anatomical comparisons be misleading
when trying to determine how closely related to
species are?
____________________________________________
____________________________________________
____________________________________________
Evidence for Evolutionary Relationships
Biochemical Evidence:
• ______ sequence (also known as genetic evidence)
• Protein sequence: since each gene encodes a
protein, changes in the gene will be reflected in
changes in the amino acid sequence of the protein.
Discuss with your table partner:
Go to the website (see link in evolution folder by
Evolution Notes Part 3:
http://ngm.nationalgeographic.com/2013/07/125explore/shared-genes
Drag the different organisms to the correct
percentage of DNA the species has in common with
humans (consider how closely related each is to
humans and use trial and error as needed.)
.
Biochemical evidence is considered to be the most
_____________ way to compare evolutionary
relationships among species.