Download Evolution Study Guide

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Evolution Study Guide
Evolution
o Change in the inherited traits of a population of organisms over the
course of generations
Darwin’s Theory of Evolution
o Common Ancestry
 Organisms inhabiting the planet today are connected through a
series of organisms living in the past
o Natural Selection
 Reproduction and survival are influenced by the
characteristics of an organism in relation to its environment
 Many individuals die before they mature
 Individuals in a population are therefore in constant
competition
 Traits in surviving organisms will be passed to the next
generation
o Two Primary Contributions
 All species on Earth are related
 Only the fittest survive and reproduce
Common Descent
o Anatomy and DNA sequence similarities show that all organisms are
related, and connected to other organisms that lived in the past
Evidence for evolutionary history
o Some of this history is recorded in the fossil record, which documents
simple, bacteria-like life as far back as 3.5 billion years ago, followed
by a long history of diversification, modification, and extinction.
o The evidence for descent from common ancestors lies also in the
common characteristics of living organisms, including their anatomy,
embryological development, and DNA.
Following Scenarios Is An Example Of Evolution?
o A mutation arises among a population of birds that allows birds
possessing that mutation to fly more efficiently than birds with the
‘normal’ form of that gene. One hundred years later all birds in the
population have the new mutation and all birds fly more efficiently
than they had flown before.
 Yes
o A mutation occurs in a particular sequence of DNA but it does not
affect any actual physical character or behavior. Nevertheless, chance
events occur such that this mutated sequence replaces the original
sequence in the population after some number of generations.
 Yes
o Wild dogs are domesticated by humans and artificially selected
through breeding programs to produce features desirable to their
owners.
 Yes
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o Heart disease among Americans has risen from 20% to 31% in the
past 5 years.
 Possible
o Radioactive waste causes genetic mutations among a population of
deer, which in turn results in these deer having high rates of
carcinoma. The radioactive waste is cleaned up but future
generations of deer still experience elevated cancer rates.
 Yes
o A mutation occurs in a group of salamanders that causes the
salamanders to have deformed limbs. Because these salamanders
tend only to mate with their close relatives, after 10 generations new
(mutant) gene has replaced the original gene in the population (ie, all
salamanders now have deformed limbs).
 Yes
o 65 Million years ago, a large meteorite impacted the planet near the
Yucatan peninsula of Mexico.
 No
o Approximately 3.6 billion years ago, life on Earth began.
 No
One example of evolution and one that is not
o Dinosaurs evolving into land birds (emus, chickens, etc.)
o Genetically modified chickens to not have feathers.
Whale Evolution
o Whale bodies look superficially like fish bodies. What are some traits
that whales and fishes share?
 Oil based skin
 Fins
o What evidence do we have that whales are not closely related to fish?
 Skeletal structure, muscle movement, blowholes, small bone
structure where hips should be, birth to live young.
 Hip bones, breathe air, teeth structure
o What scientific evidence do we have that whales evolved from a land
mammal? List at least 5 things.
 Hip Bone
 Teeth
 Skeletal Structure
 Muscle Structure
 Live Birth
o What modifications (evolutionary changes) did whales undergo as
they moved back into the ocean? (I say "back" because all of early life
was found in the ocean).
 Nostrils -> blowholes
 Legs -> fins
o Why do you think whales didn't evolve gills?
 Use to coming up for air throughout evolution process
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Carl Linneaus
o Famous for work in taxonomy
o Created single hierarchy groups of living things
Nicholas Steno
o Doctor
o Considered one of the founders of modern geology and stratigraphy
o Dissected a shark and realized that the shark’s teeth were similar to
those found in the ground and where determined to be fossils
o Fossils are remains of once living organisms
Georges Buffon
o Earth formed long ago based on physics
o Life formed along time ago, but has changed since
James Hutton
o Advocated uniformitarianism (things have been the same over time)
o Selection experiences with animals (breeding)
George Cuvier
o Anatomist
William Smith
o Canal surveyor
Jean-Baptiste Lamarck
o Proposed life was driven inexorably from simplicity to complexity
o Humans and other large species descended from microbes
o Believed animals and plants could adapt to their environment
Alfred Russel Wallace
o Same work as Darwin
o Focused on survival of the fittest instead of Darwin’s natural selection
Why might the evolution of species have jeopardized the widespread
belief that contended that humans are special and/or distinct from the rest
of life?
o "To deny man's unique status is to open the floodgates of anarchy!"
How does natural selection act on the HIV viruses within the bodies of an
infected person taking antiviral drugs? Can drugs make the infection
worse?
o HIV adapts and makes new DNA strings to counteract the
medications doctors prescribe.
o HIV evolves through white blood cells causing mutations in the
blood stream.
o Mutations reproduce constantly within someone’s blood stream.
o Drugs can make the infection worse due to the virus's adaptations
to the drug.
How has our knowledge about natural selection helped us to develop new
strategies for fighting HIV? What are those strategies?
o Doctors changed the environment of the drug-resistant virus which
encouraged the non-drig-resistant virus to flourish and replace the
population of HIV in the patient's body, so their virus was once
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again susceptible to drugs
M&M Experiment
What type of bag did you have: open or closed? Open
Did evolution occur in your population of M&M-people?
o Yes
What was the primary driver of this evolution?
o Natural Selection
Do you think evolution occurred in the other type of bag (the type your
group did not work with).
o Yes because inheritance traits changed over time due to
the percentage of left of the remaining population
What do you think the primary driver of evolution was in this other type of
bag?
o Random Change
Common Ancestry
o After class today you encounter Megan Fox, a living chimpanzee,
and a living bacterial cell. Which of these is the common ancestor?
Draw the relationships between these three organisms to support
your answer.
 Living bacterial cell, then the chimpanzee, then Megan Fox.
None are common ancestor due to the fact that they are all
alive presently, in the scenario.
What are some unique features shared by:
o All primates?
 Opposable thumbs, forward facing eyes, finger nails.
o All mammals?
 Hair, live birth, provide milk for their young, warm blooded
o All vertebrates?
 Vertebral column (back bone)
o All animals?
 Multicellular organisms
o All eukaryotes?
 Nucleus
o All living things?
 DNA and RNA, reproduction, carbon based
What is Life?
o Condition that distinguishes plants and animals from inorganic
things (water and rock)
Andrew Knoll Interview
o How does Knoll distinguish between “local” and “global” definitions
of life?
 Local-proteins and nucleic acids interact in ways that allow
the structure to grow and reproduce. It's that growth and
reproduction is important.
 Global- a system that is capable of Darwinian evolution,
meaning, a change in inherited traits over time
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o In what ways are we similar to bacteria? In what ways are we
different?
 Similarities- same proportions of carbon, oxygen, and
hydrogen
 Differences- Humans are multicellular, bacteria are
unicellular but work in very sophisticated groups
o How can we try to study the origin of life? What problems stand in
our way?
 We know that things have happened, however we do not
know how the building blocks of life started to work together
to create more living things.
Francesco Redi
o Experiment: Disproved "spontaneous-generation" using closed and
open jars and old meat.
o Result:
 Open Jars= Maggots and flies.
 Closed Jars= No maggots and flies
o Interpretation of Result: Life can't form from nothing
Lazzaro Spallanzani
o Experiment: Boiled microbes in water for an hour
o Result: The microbes died
o Interpretation of Result: To be able to generate life, you have to
have life
Louis Pasteur
o Experiment: Sterilized items and recorded whether bacteria regrew
on the items
o Result: Bacteria did not spontaneously generate on those items
o Interpretation of Result: Bacteria, therefore life, cannot generate
without life previously existing
Are these good tests of the hypothesis that life cannot evolve from nonlife?
o Not good test to the hypothesis because they are not testing the
question correctly
Miller-Urey Experiment
o Parts
 Electrical Spark- gases replicating the primitive atmosphere
 Condensor- cold water
 Sampling Probe- cooled water containing organic
compounds
 Heat Source- Boiling water
 Vacuum Pump- Repeated process
o Why did they set up this way?
 Replicate the conditions of early Earth
o What did they discover? What does this tell us about the origin of
living things?
 Discovered that amino acids were created
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Testing Hypotheses About Complexity
o Evolution / life has a goal to become more complex
 Support: Seeing all branches of life converging in producing
the same result
 Refute: Noticing that they don't produce the same result and
are diverse
o Evolution makes things "better", and that means more complex
 Support: Seeing more-complex organisms more successful
in every environment
 Refute: Seeing that less-complex life is as successful as
more-complex life
o Complexity results as a natural by-product of evolutionary change.
 Support: Building an independent system of life and seeing
that it naturally becomes more complex
 Refute: Seeing the independent system of life not become
more complex
Drunkard Experiment
o What happens to the drunkard?
 Fall into the gutter eventually
o Is this outcome the drunkard’s intended goal?
 No
o Why does this outcome occur?
 Because as long as they are moving, there is no other place
to go
o Using the drunkard metaphor, what is the “bar door” in this case?
What are the drunkard’s steps? What is the gutter?
 The "bar door" has 0 innovations (simplest organism).
 Drunkard steps are adding or subtracting innovations (traits).
 The gutter is having 4 innovations ((4 traits (most complex
traits)).
Hypotheses For Increasing Complexity
o Evolution/ Life has a “goal”
o Evolution makes things “better” and that means more complex
o Complexity results as a natural by-product of evolutionary change
Responses to Complexity
 Most living things today are simple, single celled organisms
 Many simple organisms can survive in harsh environments
where most complex organisms cannot.
Evolution As Random?
o Mutations are random
o Evolutionary change can be random, but also can be influenced by
environment (natural selection), mating systems (sexual selection,
human directed breeding (sexual selection), etc.
o Nerveless, model predicts that even completely random change
results in overall increase in complexity
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Niche
o The ecological role and space that an organism occupies in an
ecosystem
 Examples
 Gray Wolf
o Top Predator
o Wilderness Habitat
o Diet exclusively meat
o Remote areas of North America
 Penguins
o Antarctic
o Eats fish
o Crustaceans
o Lives on land but “flies’ underwater
 Giant Sequioa
o Coastal California
o Minerals in soil
o Full sunlight
o 3 dimensions
 Food type
 Habitat type
 ‘Speed’ dimension
o Why do we see adaptive radiation events following extinctions?
 Extinctions make niches available
o Why did species #1 diversify initially, but not at any time
subsequently, even after the extinction even wiped out many
species?
 First diversification event required 2 changes to niche
dimension, while all ensuing events required only 1
o Why do you think all living organisms are descended from a single
common ancestor?
 Most niches filled by existing life forms. New life would be at
a disadvantage
o How might new life take hold on Earth?
 Extinction of all or most current life
What patterns are evident from the history of life?
o Most of the history of life has been single-cells and these still
dominate the world
 The world is and always has been a bacterial world
o Multicellular life has experienced many large extinction events
o New species have evolved after extinctions (adaptive radiations)
o Humans occupy a “blip” on the timeline of life