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Evolution
14.1-14.2
"In the struggle for survival, the fittest
win out at the expense of their rivals
because they succeed in adapting
themselves best to their environment.”
-Charles Darwin
What is Darwin talking about here?
What does this quote mean?
Objectives
1. Understand basic history of evolution
2. Identify key observations from Darwin’s
voyage
3. Two main points of Darwin’s theory
Evolution and ????
Brainstorm
• Give me 5 different land mammals
– Write on board
• What characteristic(s) do all these mammals
share?
• List other traits for each animal and how
these traits make it well suited to its
environment.
True or False?
• Evolution was first proposed by Charles
Darwin?
• False!
Overview of evolution
College notetaking time
• I need you to write down what YOU think is
important over these next several slides
• This is how lectures in college are. They
don’t TELL you what to write down.
• Some things will be in red, but it will be
your responsibility to understand it all and
write down what is necessary. I will not
give you a ton of time either.
• Remember, this lecture is on the server…
Question Authority!
• During 18th century two church doctrines
provided explanations for most questions about
biological diversity:
– Separate Creation: all creatures created independently
by God and organized into a hierarchy
– 6,000 year limit on the age of the planet
• It’s not the average person who questions 2000
years of dogma, but that’s what Buffon did--100
years before Darwin!
George Buffon (1707-1788)
• French naturalist
• Not content with existing explanations
of natural world
• Suggested that the earth might be older
than a 6 thousand years
– Noticed fossils that were similar to animals
alive today
• Historie naturelle: 44 volume
encyclopedia
– Wrestled with similarities and common
ancestry of humans and apes
Jean Baptiste Lamarck (1744-1829)
• 1799 Napoleon defeated
the monarchy--> removed
church from France-->
people from lower classes
now able to fill positions
• Lamarck becomes head of
French Royal Society of
Science
• Work with fossils
• Transformation from
primitive to complex
animals
Jean Baptiste Lamarck
• Philosophie zoologique, published in 1809, most clearly states
Lamarck's theories of evolution
• Evolution:
– Change over time
• Explained evolution as a process of adaptation:
• Inherited characteristic that improves an organisms ability to survive
Lamarck’s 1st and 2nd Laws
• The use or disuse causes structures to enlarge or shrink
• All such changes were heritable
• Is this true?
Georges Cuvier
• Just as his work was becoming
known --> upheaval in France-->
Napoleon gone --> king and church
back--> Lamarck lost position to
Georges Cuvier
• This guy lost his job to Lamarck--not
happy
• Georges Cuvier’s euolgy belittled
Lamarck
• Misstated and slandered his work
• Lamarck dead --> could not defend
himself
• Lamarck is a “buffoon.”
• 30 years went by with no talk of
Lamarck’s work or evolution
Alfred Russel Wallace (1823-1913)
• Poor, British biologist
• 1852 his ship burned
returning from Amazon (5
year expedition)
– 10 days at sea
– Thousands of specimens lost
Wallace’s Malay Archipelago
Expedition
Food List
Map of travels
The Malay Archipelago
• 1854: Expedition in the Malay Archipelago
– 125,000 specimens which included:
•
•
•
•
310 mammals
100 reptiles
8,050 birds
110,000 insects
A flash of inspiration!
• 1858: While battling a fever from
malaria on the Malay expedition, he
asked himself the question, “In
both human and animal
populations, why do some live
and some die?”
• 1858 wrote paper on evolution
– Devised virtually the same theory of
natural selection that Darwin had been
developing for 20 years, but hadn’t
published
• Wallace sent his paper to Darwin, a
naturalist he greatly admired
• Darwin was shocked!
The Delicate Arrangement
• The Victorian Period
– Upper and lower
classes
– Wallace was in the
lower class
– Wasn’t right for him to
provide theory of
evolution
• What to do?
– Darwin sought advice
from two friends,
Charles Lyell and
Joseph Hooker
The Solution: a joint paper
presented at the Linnean Society
• Hooker and Lyell arranged the
presentation
• Darwin provided abstract of his work
then submitted paper by Wallace -->
Darwin got the primacy in regard to
providing the theory of evolution
• Darwin ended 20-year delay in
publishing his own theory with On
the Origin of Species.
Important Note
• Both Wallace and Darwin came up with the idea of
natural selection INDEPENDENTLY, at the SAME
TIME.
Summarize
• Meet with your neighbor and summarize the
history of evolution. You have 3 minutes.
Charles Darwin 1809-1882
• Since it was Darwin
who received the
credit, and he did
some amazing work,
we are going to focus
on his findings
Darwin
• December, 1831, the HMS
Beagle set sail
• Darwin was a 22-year old
college graduate
Darwin’s Observations
• Galapagos islands
• Islands had unique
organisms
– Similar, yet different from
mainland organisms
• Inferred that mainland
species had changed after
colonizing islands
• Marine Iguana:
– Webbed feet to dive for
algae, skin color for
camouflage and warmth
Ideas from Geology
• Darwin read a lot
• Charles Lyell
– Proposed geological
processes could explain
earth’s features
• Mountain range can be
thrust up by earthquakes cm
at a time over millions of
years
• Darwin collected fossils of
ocean organisms high in the
Andes
• This geological evidence
pointed to 2 conclusions:
1. Earth is old
2. These slow and gradual
processes could cause
enormous change in earth
Timeline
•
•
•
•
Draw on board
Arms stretched out
Earth is 4.6 billion years old!
20cm from end, Precambrian era, (3600 mya)
earth consisted of mats of algae in marine
environment
• 3cm, dinosaurs wiped out (65 mya)
• 1mm, humans walked earth!
• Geological Calendar
Darwin’s Theory
• Began to construct a
scientific theory built on
observations, inferences, and
ideas
• Read Malthus
– Production of more individuals
than environment can support
--> struggle for existence
– Darwin applied this idea to all
species
• Published The Origin of
Species
An interesting tidbit
• Just before publication, editor
realized that the current title
wasn’t going to be a big seller
• He suggested a sub title: the
preservation of favored races in
the struggle for life
• Governments and leaders all
over the world bought into the
theory of evolution
– they wanted to preserve their
favorite races in the struggle for
life
• Book made it around world in
record time!
Darwin, the Galapagos, and the
Origin of Species
Science is provisional, it changes. It’s the best truth we
have at the time.
Origin of Species: Two Main
Points
1. Descent with modification:
–
–
–
–
•
•
All life evolved from common
ancestor -->
The first forms of life spread out
into different environments -->
Adapted to their environment-->
Changed so much, became
different species
2 species of hares adapted to
living in different
environments
What do you notice?
Origin of Species: Two Main
Points
2. Natural selection:
– only the organisms best
adapted to their
environment tend to
survive and pass on their
genes
• Natural selection is the
mechanism for evolution •Humans have always selected
• This is HOW evolution
•Breed largest cattle, pick best
happens
plants for grain
•Didn’t see big picture . . .
Evidence of Evolution
14.2
Objectives
1. Describe and understand several types of
evidence for evolution:
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•
•
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Fossil records
Geographical distribution
Similarities in structure
molecular
Evidence for Evolution
• Fossils:
– Preserved remains or markings left by organisms
• Fossil Record:
– Chronological collection of life’s remains in rock layers
– Provides evidence of earth’s changing life
• Oldest fossil evidence of life found in Greenland; chemical traces
of life in rocks 3.8 billion years old
Evidence for Evolution
• Fossils link past and
present
• Supports hypothesis
that whales, which
have no hind limbs,
evolved from landdwelling ancestors that
had four limbs
The fossils of above
whale found in Pakistan.
Lived 40 mya. No longer
used legs to support
weight.
What about the gaps?
• Gaps are due to incomplete data collection
• The more we learn about the evolution of
specific species, the more these “gaps” are
filled in by transitional fossils
• One of the first gaps to be filled in was
between small bipedal dinosaurs and birds
• Discovered just two years after Darwin
published On the Origin of Species
Archaeopteryx
• 145-150 million year old
fossil
• Jaws w/teeth and long
bony tail like a dinosaur
• Broad wings and feathers
like birds
• Skeletal features of both
• Verified that birds have
reptilian ancestors
Archaeopteryx tail feathers
Archaeopteryx fossil
Archaeopteryx recreation
Lucy in the Sky with Diamonds
Evidence for Evolution:
Geographical Distribution
• Geographical Distribution:
• 60,000-40,000 years ago Australia had over 100
species of marsupials(kangaroos, koalas, wallabies,
wombats, bandicoots, and opossums) and no placental
animals (dogs, cats, bears, horses). Why?
– Explanation: these species had been evolving in isolation for
millions of years
• Tropical islands w/ similar environments in different
places in the world
– Species on island have more similarities with nearest
mainland than each other
Evidence for Evolution
• Homologous structures:
– Structural similarities
– Human arms, cat forelegs, whale flippers, and bat
wings all have same basic combo of bones.
– Functions different, but structure similar
• Similarities in Structure (activity 14.2)
Evidence for Evolution
• Structures that originally functioned one
way in ancestral species become modified
as they take on new functions
– Old people have knee or back problems
– human spine and knee joint were derived from
ancestral structures that supported four-legged
animals. . . not two legged mammals that
walked upright!
Evidence for Evolution:
Molecular
• Molecular Biology:
• Sequences of DNA passed from parent to offspring
– Genes and proteins that are very similar --> closely related
• If humans and primates closely related, then they should share
much of their DNA and protein sequences
• What do you notice in the diagram?
More Molecular Evidence
• 99% of the proteins, carbohydrates, fats, and other
molecules of living things are made from only 6 of the
92 most common elements.
• Amino Acids
– There are only 20 amino acids that make up the tens
of thousands of proteins in living things!