Transcript Evolution notes - Solon City Schools

Evolution
Charles Darwin
• 1700’s- Natural Theology dominated the time
which said adaptations of organisms was
evidence that the “creator” had designed
every species (specifically created) for a
particular purpose for a particular
environment.
• *BIG DIFFERENCE BETWEEN EVOLUTION VS.
CREATIONISM
• -Idea that all species were created at same
time says they would all appear in rocks of
same age but this in contrast to what
paleontologists observe because some
species appear than disappear in different
rock layers.
• Jean Baptiste Lamarck- (1744-1829)
• -published theory of evolution in 1809 (year
Darwin was born)
• -was in charge of invertebrate collection at
Natural History Museum in Paris
• -saw many ladders of life that species could
move up (toward greater complexity)
• -Evolution-according to Lamark was toward
greater complexity
• Lamarck’s Mechanism for Evolution
• 1. Use/Disuse
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Parts used= larger/stronger
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Parts not used= deteriorate (waste away)
• 2. Acquired Characteristics- modifications
acquired during lifetime can be passed to
offspring (ex. Long giraffe neck)
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-NO EVIDENCE YET THAT GENES ARE CHANGED
BY THIS
Lamarck’s theory of acquired
characteristics
• Charles Darwin-(1809-1882) born in Shrewsbury,
England
• -read nature books- liked to fish, hunt, & collect
insects as a boy
• -Charles earned his B.A. in 1831 & went w/ Captain
Robert Fitzroy to sail on HMS Beagle
• -goal of the voyage  chart poorly known
stretches of the South American coastline
Voyage of HMS Beagle
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-Darwin
spent most of his time collecting
diverse/exotic species
-Darwin noticed plants/animals had different
characteristics than those in Europe
*PUZZLING- Galapagos Islands- 900 Km west of
South America but he saw animal species on Gal.
that weren’t found in other parts of the world
ex. Finches- 13 types collected; very similar
but differed most in beaks  adapted for
special diet
-large ground finch- large beak for cracking
seeds
-small tree finch- beak used to grasp insects
Darwin’s finches
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Darwin’s Findings
Origin of new species
Closely
related
Adaptation to environment
*Finch results- Darwin believed that if 1
species is separated by a geological barrier
they could become dissimilar to be called
different species
• Darwin’s evidence for evolution
• 1. Biogeography- islands  species of
plants/animals that are native to island but
are closely related to mainland species
• 2. Fossils- Bacteria  prokaryotes are earliest
known fossils so they should precede all
eukaryotes
• *Fossils do show this order (prokaryotes 
eukaryotes)
• ex. Vertebrate record
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fossil fishes  amphibians  reptiles
mammals birds
• Darwin’s Beliefs about Evolution
• 1. Struggle to Survive
• 2. Individuals who inherit characteristics
that best fit the env. will leave more
offspring than less-fit individuals
• Evolution- change in populations over time
• Charles Darwin- (1809-1882)
• -published On the Origin of Species (1859)
which had 2 points:
• All species evolve from ancestors
• Mechanism for evolution  natural selection
• Evolution according to Darwin
• *Natural Selection- mechanism for change in
populations
• 1. Organisms produce more offspring than can
survive
ex. Fish lay millions of eggs
• 2. In any population, individuals have variations
ex. Fish differ in size, shape, color,
speed, etc.
Evolution according to Darwin
• 3. Individuals with certain useful variations such
as speed are more likely to survive in their
env. passing those variations on to the next
generation
• 4. Overtime, offspring w/ certain variations
(adaptations) make up most of the population,
& may look entirely different from their
ancestors
• *Modern Biologists-define evolution as a “change in a gene pool
(gene frequency) of a population over time”
• SO, THE SMALLEST UNIT THAT CAN EVOLVE IS A
POPULATION!!
Natural Selection
This diagram shows the natural selection process for a
population with dark coloration.
• Adaptations/Structures which give evidence
for evolution
• 1. Mimicry-structural adaptation that enables
one species to resemble another species
• ex. Yellow jacket
vs.
syrphid fly
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(harmful)
(harmless-looks like yellow jacket)
• So, predators avoid eating both insects
• 2. Camouflage- adaptation that enables
species to blend w/ their surroundings
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-survive to reproduce b/c can’t be
found by predators
Flounder blending in
with sea floor rocks
• 3. Homologous Structures- can be similar in
arrangement, in function, or both
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-evidence that organisms evolved
from a common ancestor
• ex. Whale, crocodile, & bird forelimbs
are similar
Homologous Structures
• 4. Analogous Structures- body parts of
organisms that do not have a common
ancestor but are similar in function
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ex. Wings of butterfly & wings of birds
• . Vestigial Structures- body structure that has
no function in a present day organism but was
probably useful to an ancestor
• ex. Ostrich- has reduced forelimbs & can’t fly
(ancestors probably foraged for food on land
& nested on ground so they got too large to fly
Vestigial Structures
• Embryology- embryo- earliest stage of growth
& development
ex. Embryos of fish, reptiles, birds, mammals all
look the same & suggest a common ancestor