Unit VI - Evolution
~ a unifying theme of biology ~
Bell Ringer
• Page 128
– Evolution of the Cell Phone
– Cut out the the cell phones and glue them in
order 1st to most present
– Discuss the evolution of technology
Target
• Explain Miller & Urey’s experiment and
describe how it related to organic
molecules
• Explain how Redi’s & Pasteur’s
experiments disproved Abiogenesis
Introduction to Evolution PG
129
• What does biological “evolution” mean?
– Change in organisms over time
• How does this relate to the “origin of life”?
– It doesn‘t…two different topics!
– Much more evidence to support evolution
– Remember: science deals with natural world,
not belief
Introduction to Evolution
• How could “life”
have started?
– Old Idea: Abiogenesis
• “spontaneous
generation”
(abiogenesis)…no
nliving matter
makes living
• Disproved by Redi
and Pasteur
– New Idea: Biogenesis
• “biogenesis”…life
comes from life
Introduction to Evolution
• So, then where did the first cells
come from?
– H, C, N, S (Hydrogen,
Ammonium, Methane)
– Early earth
• Very hot; volcanoes; violent
storms/lightning
– Miller & Urey experiment
• Under early earth conditions,
organic compounds form & group
together into “protocells” (a selforganized, endogenously
ordered, spherical collection of
lipids proposed as a steppingstone to the origin of life.)
Introduction to Evolution
• But, when did we actually get cells? And how?
– Evidence of first cells
• 3.4 bln yrs ago
• Most likely anaerobic bacteria (no O2 in air)
– First photosynthetic cells
• 2.8 bln yrs ago
• Increased O2 in atmosphere
• Led to ozone layer that protects from UV rays =
more cells
• Aerobic cells could now develop
Recap 8-1
• Evolution- change in organisms over time
• Evolution related to “origin of life: they are two
different topics, more evidence to support
evolution, science deals with NATURAL
WORLD not BELIEF
• Abiogenesis- old idea where non-living matter
made living) spontaneous generation
• Biogenesis- new idea where life comes from life
• Miller & Urey- under early conditions, organic
compounds form & group together into
“protocells”
Bell Ringer
• On page 130: Compare and Contrast
Redi’s & Pasteur’s experiments
• Pick up your paper and go to a lab table
groups of 4-5 per table
• Find the years, explain the experiments,
include if they had more groups then your
paper shows and draw/explain if it does
• Be prepared to discuss with the class!
Target
• Describe the assumptions that Darwin made in
forming the theory of natural selection
• List examples of indirect evidence that support
the theory of natural selection
Darwin’s Idea PG 131
• How did Darwin form ideas about evolution?
– Fossils showed organisms changed over time
Darwin’s Idea
• How did Darwin form ideas about evolution?
– Geologists showed that earth was very old
Darwin’s Idea
• How did Darwin form ideas about evolution?
– Malthus noticed populations grow faster than their
food supplies (they produce too many offspring)
Darwin’s Idea
• How did Darwin form ideas about evolution?
– Artificial selection is the idea that breeders could cause
major changes in the features of plants and animals over
a course of decades
Darwin’s Idea
• How did Darwin form ideas about evolution?
– He saw diverse species (ex: finches on Galapagos
Islands, all with variations)
Adaptive Radiation
• is a process in which
organisms diversify
rapidly into a multitude
of new forms,
particularly when a
change in the
environment makes
new resources
available, creates new
challenges, or opens
new environmental
niches.
Darwin’s Ideas
• What did Darwin
conclude about
species?
– He identified that
populations change due
to “natural selection”
(nature selects who
goes on)
Darwin’s Ideas
• What did Darwin conclude about species?
– Four assumptions:
• Populations produce large #’s of offspring
(more than can survive with given food)
• Individuals in population have variations
• Certain variations are more useful (these will
survive better)
• Over time, “good” genes prevail in the
population, while “bad” ones fade out
Evidence for Evolution
• What direct evidence supports this
theory?
– Not much because we have not lived long
enough, but some examples:
• Ex: peppered moth
Evidence for Evolution
• What direct evidence supports this theory?
– Structural adaptations
• Ex:
- mimicry – organisms resemble another
organism
- Camouflage –
blending with the
environment
Evidence for Evolution
• What direct evidence
supports this theory?
– Physiological changes
• Ex: drug-resistant
bacteria;
• Ex: pesticide-resistant
insects
Recap! 8-2
• Darwin’s ideas fossils, geology,
population studies, artificial selection,
diversity of species
• Natural selection based on four
assumptions
• Evidence that supports this theory not
much, some exps are: peppered moths,
structural adaptations, physiological
changes
Bell Ringer
• Charles Darwin & Alfred Wallace
– Read the paper given, do not write on it
– On Page 132 reflect on the paper
•
•
•
•
•
•
What are the main ideas of the paper
What are the main organisms they talked about
What are the pre-Darwinian ideas of evolution
What is pressure of population growth
What is significant about pigeon breeding
What is origin of species
Target
• Recognize examples of analogous,
homologous, and vestigial structures
• Explain why individuals cannot evolve, but
populations can evolve
Evidence for Evolution PG 133
• Is there indirect evidence of evolution?
– Fossils
• show changes through time
Evidence for Evolution
• Is there indirect evidence of evolution?
– Anatomy
• Homologous structures
– Similar origin/structures, but may now have different
function
– Shows common ancestry
– Ex: bat wing, whale flipper, human arm
Evidence for Evolution
• Is there indirect evidence of evolution?
– Anatomy
• Analogous structures
– Similar function, but very different structure
– Shows separate development…not related
– Ex: bird wing & butterfly wing
Evidence for Evolution
• Is there indirect evidence of evolution?
– Anatomy
Evidence for Evolution
• Is there indirect evidence of evolution?
– Anatomy
• Vestigial structures
– A part that no longer serves a purpose
– Ex: snake hip bones; human wisdom teeth
Bell Ringer
• Vote for the BEST Creature
– You cannot vote for your own
– Vote on adaptations, and features
Evidence for Evolution
• Is there indirect evidence of evolution?
– Embryology
• Early similarities may show relation
Evidence for Evolution
• Is there indirect evidence of evolution?
– Embryology
• Early similarities may show relation
Evidence for Evolution
• Is there indirect evidence of evolution?
– Embryology
Evidence for Evolution
• Is there indirect evidence of evolution?
– Biochemistry
• Similar chemicals in most life forms (DNA, ATP)
• More similarities in code means closer
relationship
Mechanisms of Evolution
• Can individuals evolve?
– No!
– Genes are genes…cannot alter them*
– Only populations can evolve
– Gene pool = sum of all genes in population
Recap! 8-3
• Fossils- show change over time
• Homologous structures- similar structure,
different function
• Analogous structures- similar function, different
structure
• Vestigial structures- a part that no longer serves
a purpose
• Embryology-early similarities showing relation
• Biochem-DNA, ATP, Codes with simiarities
• Populations evolve, not individuals!
Bell Ringer PG 136
• An organism that is the fittest:
A. Has the best adaptations to survive & reproduce in
its environment
B. Has the ability to hide from its predators in the
best manner possible
C. Is the strongest & therefore the best able to kill its
prey
D. Is the youngest & therefore the most active
• Structures that have a similar evolutionary
origin & structure but are adapted for different
purposed, such as the bat wing and a human
arm, are called_________.
Mechanisms of Evolution PG
135
• How do populations evolve?
– Any factor that affects genes in gene pool may
disrupt equilibrium…leads to change (evolution)
– Mutations may cause a shift
– Genetic variations may cause
changes…especially in small isolated
populations…change to concentrate recessive
traits much higher
– Genetic drift – immigration/emmigration into or out
of population
– Large populations not as affected by these factors
Mechanisms of Evolution
• How do species evolve?
– Called “speciation” (same species can breed)
– Geographic isolation
• A barrier like river, road, mountain, etc. that
keeps individuals apart so they cannot
interbreed…over time they develop different
traits (Ex: finches on different parts of the island)
Mechanisms of Evolution
• How do species evolve?
– Called “speciation” (same species can breed)
– Geographic isolation
Mechanisms of Evolution
• How do species evolve?
– Called “speciation” (same species can breed)
– Reproductive isolation
• no longer capable of interbreeding (timing,
parts, gametes differ,…)
Modes of Selection
Directional Selection
Pushes toward ONE extreme or the other
Ex: in dry years, beak size pushed to larger
Mechanisms of Evolution
• Does evolution show patterns?
– Convergent evolution- distantly related organisms
with similar traits
Disruptive Selection
Pushes toward both extremes
Ex: small beak for soft seeds; large beak for hard seeds;
medium beak is bad at both types of seeds so selected
against
Stabilizing Selection
• Pushes to average
• Ex: cactus with few
spines eaten by
animals more; cactus
with too many spines
invaded by more
parasites
Three Types of Selections
Mechanisms of Evolution PG
137
• How fast can species evolve?
– Gradualism
• Species start up over long time with gradual
changes (millions of years)
– Punctuated equilibrium
• Speciation occurs in quick bursts with
equilibrium in between (~10,000 yrs or less)
Mechanisms of Evolution
• How fast can species evolve?
Mechanisms of Evolution
• Does evolution
show patterns?
– Divergent
evolution
• Ancestral
species evolves
into many
species that fit
different habitats
• Ex: finches;
common on
islands
Mechanisms of Evolution
• Does evolution show patterns?
– Convergent evolution
• Distantly related organisms end up with similar
traits
• Occurs when have similar habitats
• Ex: cactus in S. American & African deserts
Quiz – Evolution
for use with Questions 1 & 2
Quiz – Evolution
for use with Questions 3-5
Quiz – Evolution
for use with Question 6
Quiz – Evolution
for use with Question 7