Download Evolution Student Notes

16.1 and 16.2 (use worksheets)
Important main points:
a) What are Charles Darwin’s contributions to science?
b) What are the three patterns of biodiversity that were noted by Darwin? What are examples of each?
c) What is the importance of Hutton, Lyell, Lamarck, and Malthus in terms of shaping Darwin’s ideas?
d) How is artificial selection different from natural selection, and how has artificial selection been used
over time by humans?
16.3 Notes - Darwin Presents His Case
Based on his experiences in travel, and research of other scientists’ data, he created a draft of his thoughts on
_______________________ ________________________ but he waited _____________ years to publish it!
Why so long? Because he saw the backlash that other scientists received for their ideas so he decided to wait
and gather more _______________________ to support his ideas. What finally forced him to publish his work
on evolution (On the Origin of Species)? Another scientists, Alfred Russell Wallace, was about to publish a
book with the same thoughts as Darwin. He didn’t want to lose his credit so he was forced to publish early.
His four main points
1) The Struggle For Existence
a) Based on reading ______________________ he explains that if
there are more organisms born then the environment can
provide space/food for some will live while others will
_______________. This brings up the important question of
who survives and who doesn’t? Darwin states that those overall
_____________________________________ for their
environment (the fittest) will survive.
b) The more ____________________ the environment the more organisms it can hold (Harsh desert vs.
thriving jungle)
2) Variation and Adaptation
a) Due to ______________________ reproduction all offspring will
be genetically different and will provide genetic variations into a
population. Those variants that are better suited for their
___________________________ will survive.
b) Those that survive will then pass on those better suited traits
onto their _______________________.
i) Any heritable characteristic that increases an organism’s
ability to survive and reproduce in its environment is called
an _________________________________. coloration, claws, wings, camouflage, mimicry, etc
3) Survival of the Fittest
a) Darwin used the term “____________________” to give a level
to how well suited an organism was for its environment. Those
with ____________ fitness are well suited to their environment
and can survive and reproduce at high rates. However those
with ______________ fitness are not suited to their
environment and reproduce at very low levels. (few offspring is
bad!)
i) Question: If an organism produces many offspring, but
none of them reach maturity, do you think the organism has
high or low fitness? Explain why. ______________________________________
_______________________________________________________________________________
_______________________________________________________________________________
b) He summed up all of this with his term survival of the _______________________ where survival
means having the ability to pass on your genetics and adaptations to future generations.
4) Natural Selection
a) In natural selection the ________________________
influences fitness.
b) Natural selection occurs when:
i) More individuals are _________________ than can
__________________.
ii) There is natural heritable
_____________________________.
iii) There is variable _______________________ among
individuals.
c) Those with the highest fitness will adapt and ________________ and those with the lowest fitness will
_______________ off.
d) Natural selection only works for ________________________ traits. Note that this is not the ONLY
mechanism driving evolution… more to come!
5) Descent with modification
a) He proposed that over time new species form that are
_______________________ forms of their descendents.
b) He used evolutionary __________________ to show how different species
came from one original descendent. According to this principle all
organisms are descended from ancient common
______________________.
16.4 Notes – Evidence of Evolution
1) Important Points:
a) Evolution = _____________________
b) The mechanism of how organisms change over time = ________________________ (it is
testable/falsifiable)
c) Also evolution is not about ________________ it is about _____________________.
2) Biogeography is the study of where organisms live ____________ and where they lived in the __________.
a) The patterns formed in the distribution of living and _________________ species tell us how modern
organisms evolved from their ancestors. (movement, environment, etc.)
b) Many __________________ discovered fossils, are filling in the fossil record, and helping to complete
the tracing of evolution of _____________________ species from extinct ancestors.
3) Homologous Structures
a) A clue to common ______________________ from an ancient ancestor.
b) Common ___________________, but NOT common _____________________.
c) See example to the right:
d) This is synonymous (similar in definition to) ________________________ evolution.
Divergent evolution is the accumulation of differences between
groups which can lead to the formation of new species, usually a
result of diffusion of the same species to different and isolated
environments which blocks the gene flow among the distinct
populations allowing differentiated fixation of characteristics
through genetic drift and natural selection.
4) Analogous Structures
a) This is not a form of common descent.
b) Body parts that share common _________________________, but NOT ___________________.
c) Ex: wing of a bee vs. wing of a bird. Both _______________, but they are not built nearly the same.
Both acquired the wing to help with flight.
d) This is synonymous with _____________________ evolution.
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.
5) Vestigial Structures
a) Structures that are passed from generation to generation but have no _________________ use.
i) Ex: Dolphins hip bones
ii) Ex: Wings of the flightless cormorant
iii) Ex: Legs of the Italian three-toed skink (it moves by slithering like a snake)
iv) Ex: Human appendix
v) Ex: tiny skin covered eyes of a Blind Mole Rat
b) Why do organisms keep these if they are not of use?
i) Scientists are not 100% sure but the current theory is that the presence of the structure does not
hurt the organisms _______________________ level for survival and therefore natural selection
doesn’t act quickly to eliminate it.
6) Embryology
a) In the picture to the right the
top row is the actual organism
where the bottom row is an
artistic rendering pointing out
significant features. How are
the different pictures across the
top similar? How are they
different?
_________________________
__________________________
___________________________________________________________________________________
___________________________________________________________________________________
b) Do you think they all come from the same lineage of organism? Why or why not?
____________________________________________________________________________________
___________________________________________________________________________________
7) Life’s Common Genetic Code
a) The strongest evidence for descending from a common ancestor is based on ____________________.
b) The Human Genome Project has coded the genetics of a vast number of organisms and guess what?
We are all VERY ____________________. To the point where the genetic code is nearly identical in
almost all organisms (bacteria, yeasts, plants, fungi, and animals). There must have been a common
ancestor at one point in order for this to happen.
IMPORTANT note on 16.4: you need to use the book to read on the Grants finches, biogeography, and
genetics
17.1, 17.2, and 19.2 Notes
1) Evolution, in genetic terms, involves a change in the frequency of _____________________ in a
POPULATION over time.
a) If the frequency of an allele is increasing or decreasing it means that a population is evolving. Judged by
looking at the gene pool of populations genes.
2) Natural Selection vs. Evolution
a) Natural Selection happens to __________________________, but the changes that it causes in the allele
frequency shows up in the _______________________________ as evolution.
b) IMPORTANT: The smallest unit that can evolve is a _________________________ NOT individuals.
3) 3 Sources of Genetic Variation
a) Mutations
b) Genetic Recombination in Sexual Reproduction (passing from parents to offspring)
c) Lateral Gene Transfer (important for single celled organisms where they swap genes through plasmids)
4) Single Gene vs. Polygenic Traits
a) Single Gene traits are much more ____________________ as they only involve one gene and can lead to
allele frequency changes faster.
b) Polygenic Traits require more than one gene and therefore take a much _____________________ time to
affect the allele frequency.
5) Natural Selection acts on Variations
a) Stabilizing selection- natural selection that favors the ______________________ individuals in a
population. (Average birth mass of baby survives!)
b) Disruptive selection- individuals with either
_______________________ of a trait’s variation are
selected for to survive. The
_________________________ phenotype tends to be
eliminated. (small and large beak size survives if
small/large seeds are in abundance)
c) Directional selection- natural selection that favors
____________ of the _________________ variations.
(woodpecker with longer beak survives since it can get
food easier from tree)
Note: species are organisms that look alike and can
interbreed to produce fertile offspring.
i)
Geographic Isolation:
________________________________ may prevent this reproduction from happening. A volcano
eruption or a river may isolate a species. Therefore, a _________ species may evolve. These new
organisms adapt to their new environment and start their own gene pools.
ii) Reproductive Isolation: Different ___________________________ and the ability to fertilize an
organism of the same species could also result in speciation. NOTE: speciation means to form a
new species.
iii) Nondisjunction: Changes in ____________________________ number can also cause speciation,
which is seen in wheat and apples.
6) 2 Theories about Evolution - Speciation can occur quickly or slowly
a) ___________________________- species originate through a gradual change of adaptations slowly.
b) ___________________________ equilibrium- speciation occurs quickly in rapid bursts due to changes in
geography, climate, predators.
*****Both views are supported by fossil evidence*****
7) Background Extinction vs. Mass Extinction
a) _______________________ extinction is coined “business as usual” extinction because there is a natural
competition of evolution and survival over a longer period of time.
b) Whereas _______________ extinction is a relatively rapid extinction where entire
___________________________ vanish, whole food webs collapse, species go extinct due to
________________ loss, and the process of natural selection just cannot compensate quickly enough.
i) What can cause these extinctions? _________________________, global climate change,
volcanoes, moving ________________________, and changing ________________ levels.
ii) After this many species go extinct which leaves space for other species to take over. This rebuilding
can take anywhere from 5 to 10 ________________ years.
8) Adaptive Radiation
a) This is the process by which a single _______________ or a small group of species evolve over a relatively
________________ period of time into several different forms that live in ________________________
ways.
i) This is what Darwin discovered in the finches on Galapagos Island.
b) After the ____________________ went
extinct an adaptive radiation occurred
which brought a large variety of organisms
into the population.
9) Coevolution
a) When two different __________________
are so closely linked that they evolve
together.
b) Ex. of a GOOD relationship: Flowers and Pollinators
i) Flowers need to pollinate and ___________________ (ex: bees, moths, etc.) want the nectar inside
the flower. Pollinators will adapt to best retrieve the nectar and in turn by more pollinators being
able to get the nectar the flower will pollinate more often.
c) Ex. of a BAD relationship: Plants and Herbivores
i) Herbivores like to eat plants. Over time plants have evolved bad-tasting or poisonous compounds
that keep herbivores from eating them. In response the herbivores will adapt to be able to be
_____________________ to such poisons (or even be able to store it in their tissues to ward off
predators). And so the cycle continues.
(1) NOTE: this relationship that has caused plants to be so poisonous has created some of the
most ______________________ natural poisons used by humans.