Evolution: Key Concepts and Perspectives
1
Lecture #1 – Darwinian Evolution
Image of Darwin
2
Key Concepts:
•
Evidence for evolution
•
Darwin’s theory
•
The Modern Synthesis
3
Spiritual
vs
. Intellectual
Different, but not necessarily in conflict
The human emotional experience
The human intellectual experience
“
The Bible tells us how to go to Heaven, not how the heavens go
”
Galileo
4
Reality Check:
The world’s major religions and the dominant
religion in the world’s four most populous countries
SOURCE – National Geographic, December 2007
5
There are many equally valid ways
“to go to Heaven”
•
We rely on our religious texts for moral,
emotional and spiritual guidance
•
We rely on science and other intellectual
pursuits to gain knowledge about the
natural world
There need be no conflict in these different
ways of thinking and learning
6
Images – species, population, community
Some preliminary definitions
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Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
8
Image – finches on the Galapagos
Photographs by B. Rosemary Grant/
Science, 2006
Historical Evidence: observed character
displacement
Changes in beak size recorded over about 2 decades
after a natural migration event
Big-beaked invader
Resident species shifted
to smaller beak size
9
Image – rice
All of agriculture is based on
human selection events
•
The domestication of
grass ~12,000 years ago
•
Led to the first cultural
shift in human civilization
Nomadic hunter-gather
tribes
villages based
on agricultural production
•
Other plants and
animals as well….
Artificial Selection –
Brassica
oleracea
in all its forms
10
Image – cabbage, kale, cauliflower, broccoli, Brussels sprouts
11
Images – different
breeds of cattle and
chickens
Farm Animals – different breeds
12
Images – different
breeds of cats and
dogs
Cats and Dogs
A great dane is the same species as a toy poodle!
13
Diagram – development
of pesticide resistance
due to use of insecticides
The development of pesticide
resistance
•
Resistance to
insecticides,
herbicides,
antibiotics…..
•
All natural responses
to human generated
changes in the
environment
14
Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
15
Images – fossils of plants and fish
The fossil record extends back
BILLIONS of years
16
Diagram – formation of sedimentary rocks with fossils embedded
Most form in marine sediments
17
Images – other fossil substrates
Fossil substrates
–
can you think of others???
18
Formation of sedimentary rocks is
not uniform in time or space
Diagram – formation of sedimentary rocks with fossils embedded
19
Critical Thinking
•
The formation of sedimentary rocks is not
uniform in time or space
•
Why not???
20
Critical Thinking
•
The formation of sedimentary rocks is not
uniform in time or space
•
Why not???
•
Dynamic processes!
Geological activity
Climate
Depositional environments
21
Formation of sedimentary rocks is
highly dynamic
•
Varies with geological activity
Tectonic movements, mountain building,
erosion
Varies with climate
Rain, wind, freeze/thaw cycles, water
temperature – all affect erosion and
sedimentation
•
Varies with the depositional environment
Finer sediments in still water, coarser
sediments with more wave action or other
energy
22
Diagram – dynamic geological processes:
tectonic movements, mountain building, erosion
The earth’s crust is very dynamic
23
Formation of sedimentary rocks is
highly dynamic
•
Varies with geological activity
Tectonic movements, mountain building,
erosion
•
Varies with climate
Rain, wind, freeze/thaw cycles, water
temperature – all affect erosion and
sedimentation
•
Varies with the depositional environment
Finer sediments in still water, coarser
sediments with more wave action or other
energy
24
Graph of benthic carbonates –
analogous to climate change over the
past 5 million years
Climate is naturally dynamic on
a geological time scale
Benthic carbonates parallel atmospheric
temperature changes
25
Critical Thinking
•
How could water temperature affect the
formation of sedimentary rocks???
26
Critical Thinking
•
How could water temperature affect the
formation of sedimentary rocks???
•
Limestone is a sedimentary rock that is
formed from the tiny shells of marine
organisms
•
The abundance of these organisms is
partially dependent on water temperature
27
Formation of sedimentary rocks is
highly dynamic
•
Varies with geological activity
Tectonic movements, mountain building,
erosion
•
Varies with climate
Rain, wind, freeze/thaw cycles, water
temperature – all affect erosion and
sedimentation
•
Varies with the depositional environment
Finer sediments in still water, coarser
sediments with more wave action or other
energy –
WHY???
28
Play with the “ocean”
•
In high energy environments (waves) only
the heaviest sediments can settle
Coastal environments produce sandstones
•
In off-shore environments (no waves) finer
sediments can settle
Off-shore environments produce siltstones,
slates, limestones…
29
Diagram of different depositional environments
Sediment size depends on the energy level at
the site of deposition
30
Formation of sedimentary rocks is
highly dynamic
•
THUS sediments tend to be deposited in
identifiable layers
•
THUS organisms trapped in sediments
form a time sequence
The earliest organisms are in the bottom
layers and the most recent organisms in the
upper layers
31
Image – the Grand Canyon showing layers of sedimentary rock
The Grand Canyon – a time sequence
32
Formation of sedimentary rocks is
highly dynamic
•
THUS sediments tend to be deposited in
identifiable layers
•
THUS organisms trapped in sediments
form a time sequence
The earliest organisms are in the bottom
layers and the most recent organisms in the
upper layers
Dating these fossils reveals the history of
change
33
The geological time scale
Study the
geological time
scale – it’s the
history of life on
earth!
Use a search
engine to find the
geological time
scale
34
Of course the fossil record is
incomplete!
•
Organisms must be trapped in the right
place under the right conditions – a rare
event
•
Fossils must survive geological processes
such as subduction, metamorphosis and
erosion
•
Fossils must be found!
Have you ever found a fossil???
•
But what we do have is irrefutable evidence
of change over time
Fossil Evidence Shows Progression
Over Time – new species….
35
Diagram – evolution of elephant lineages
36
Diagram – limbs developing from bony fins in tetrapods
….new traits….
37
Diagram – transition from bony fins to limbs
….transitional forms….
38
Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
Comparative morphology – homologous
structures are derived from a common ancestor
39
Diagram – forelimbs of various mammals
showing identical bone structure with
variation in bone size
40
Diagram – similarities in the embryos of a
wide variety of vertebrates
Fish
Salamander
Tortoise
Chicken
Pig
Cow
Rabbit
Human
Strickberger, 1996
Stage of
Development
Early
Later
41
Images – orchid floral structure
42
Comparative morphology –
vestigial traits
•
Structures that are physically or
functionally reduced but clearly similar to
functional structures in related organisms
Tiny limb bones in some snakes and aquatic
mammals
Non-flying wings in ostriches emus, kiwis,
penguins
Blind eyes in cave-dwelling animals
Vestigial tails in humans
43
Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
Biogeography – Darwin observed patterns
of species distribution during his voyage on
the Beagle
44
Diagram – the voyage of the Beagle
45
Image – modern and fossil sloths
Sloths – found only in South America, even though
similar habitats exist on other continents
46
Diagram of marsupial and eutherian mammals showing similar forms
Marsupials – almost restricted to Australia
…though convergent evolution has resulted in many
similar eutherian mammals on other continents
Convergent evolution –
similar traits in unrelated
organisms that evolved
under similar selection
pressures….more later
47
The Gal
á
pagos and other volcanic islands
Many closely related endemic species….that are
similar to those found on the closest mainland
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Diagram of Darwin’s finch lineages
48
Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
49
Image – frog in the center of a bromeliad
Uniformity and Diversity:
same DNA, same ATP, same amino
acids, same membranes, same
aerobic respiration….
50
Critical Thinking
•
What is the implication of this uniformity in
the basic building blocks of life, even
though there are many millions of
organisms both extant and extinct???
51
Critical Thinking
•
What is the implication of this uniformity in
the basic building blocks of life, even
though there are many millions of
organisms both extant and extinct???
•
These structures and processes emerged
at the very beginning of life on this planet
and have been conserved in all organisms
throughout evolutionary history
52
Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
S
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H
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Hands On
•
Let’s take a walk
•
Work in pairs
•
Find some living things
•
Think about uniformity and diversity
•
Meet back here in 20 minutes and be
prepared to discuss your thoughts
•
Record our discussion and type up a
summary to turn in tomorrow
53
54
Defining Evolution:
•
A process of change over time
•
Cannot deny that this occurs
•
Evidence is overwhelming:
Historical – within the span of recorded
human history
Fossils – the very long term geological record
Comparative morphology and anatomy
Biogeography – the geographic distribution of
species
The unity of life
S
t
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p
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p
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55
Timeline – the development of thought on evolution
Historical Context
The development of ideas about biological evolution
and the age of the earth began in the 1700’s –
Darwin was just the first to publish!
Darwin’s voyage on the Beagle, 1831-
1836…..publication of his theory, 1859
56
Map – the voyage of the Beagle
57
Darwin’s Theory of Evolution by Natural
Selection
based on observation + logical inference
•
OBSERVATION #1
– all species have the reproductive
potential for exponential population growth
•
OBSERVATION #2
– populations tend to remain stable
OBSERVATION #3
– environmental resources are limited
INFERENCE
#1
– excess of offspring leads to a struggle for
existence
•
OBSERVATION #4
– significant variation exists between
individuals of the same species
•
OBSERVATION #5
– some variation is heritable
INFERENCE
#2
– individuals that are best adapted to their
environment contribute more offspring to the next generation =
differential reproductive success = Darwin’s natural selection
INFERENCE #3
– TIME X CHANGE = DIVERSITY
Don’t panic – this is just a summary slide for you to look at later
58
Images – examples of high reproductive potential in various organisms
Observation #1:
All species have the
potential for exponential population growth
59
Graphs – examples of
actual population growth
patterns
Observation #2:
Populations tend to
remain stable
(though sometimes within a fluctuating range)
not
exponential
60
Image – lynx chasing rabbit
Observation #3:
Environmental
resources are limited
food….
61
Image – desert landscape
water….
62
Images – various animals in habitat
habitat….
63
Image – resource competition between aquatic plants
Inference #1:
Excess offspring in a
resource-limited environment leads to a
“struggle for existence”
Observation #4:
Variation exists in all
natural populations
64
Diagram – natural variation in beetles
65
Image – natural variation in plants
66
Image – natural variation in mollusks
67
Images – natural variation in humans
68
Images – heritable variation in various animals
Observation #5:
Some variation is heritable
69
Image – polar bears fighting
Inference #2:
Best adapted individuals
reproduce the most
Differential Reproductive Success!!!
70
Inference #3:
Darwin’s Big One
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Image – orchid mantis
Key Conclusion
Small changes over long periods of time result
in adaptations to different environments and to
the emergence of new species
72
Same as previous
73
Same as previous
74
Images – additional cryptic animals; through slide #81
75
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82
Critical Thinking
•
What other testable explanation is there
for an insect or other animal that evades
predation by mimicking its habitat???
•
How else might this cryptic form and
coloration benefit the animal???
83
Critical Thinking
•
What other testable explanation is there
for an insect or other animal that evades
predation by mimicking its habitat???
None
•
How else might this cryptic form and
coloration benefit the animal???
84
Critical Thinking
•
What other testable explanation is there
for an insect or other animal that evades
predation by mimicking its habitat???
None
•
How else might this cryptic form and
coloration benefit the animal???
More likely to catch their own prey items
Predation and competition are very strong
selection pressures!
85
Diagram – mammal lineages
Darwin originally predicted gradual
speciation from a common ancestor…..
•
Now we know
that abrupt
changes are also
possible
•
Also, some
gradual changes
may not be
recorded in the
fossil record
86
Images – more cryptic animals; same on next slide
Questions Remain
•
We don’t, and may never, know exactly
how life originated on this planet
•
But we do have a pretty good explanation
for how diversity developed and why
diversity changes over time
Conditions change
Organisms adapt
87
Questions Remain
•
We don’t, and may never, know exactly
how life originated on this planet
•
But we do have a pretty good explanation
for how diversity developed and why
diversity changes over time
Conditions change
Organisms adapt
88
The Modern Synthesis
•
Darwin’s concepts of natural selection and
differential reproductive success leading to
adaptations and speciation
•
Mendel’s work on heredity and hypothesis of
a particulate method of hereditary transfer
•
Microscopic revelation of chromosomes as
that particle in the late 1800’s – early 1900’s
•
Discovery of the structure of the DNA
molecule in the early 1950’s
89
The Theory of Evolution
A comprehensive body of knowledge
that describes a known fact of nature
90
Key Concepts:
•
Evidence for evolution
•
Darwin’s theory
•
The Modern Synthesis
Questions???
Hands On
•
What are some selection pressures that
might lead to adaptations???
•
Think about what we collected earlier
•
Record our discussion and type up a
summary to turn in tomorrow
91
Explore the key concepts of Darwinian evolution, including evidence for evolution, Darwin's theory, and the Modern Synthesis. Reflect on the relationship between spiritual and intellectual perspectives, emphasizing that different ways of thinking can complement each other. Discover the diversity in religious affiliations globally and understand that science and religion can coexist harmoniously. Gain insights into preliminary definitions in biology and the overwhelming evidence supporting the process of evolution over time, including historical and morphological evidence.
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Presentation Transcript
Lecture #1 Darwinian Evolution Image of Darwin 1
Key Concepts: Evidence for evolution Darwin s theory The Modern Synthesis 2
Spiritual vs. Intellectual Different, but not necessarily in conflict The human intellectual experience The human emotional experience The Bible tells us how to go to Heaven, not how the heavens go The Bible tells us how to go to Heaven, not how the heavens go Galileo 3
Reality Check: The world s major religions and the dominant religion in the world s four most populous countries Religious Affiliation United States 82 World China India Indonesia 13 77 33 21 14 13 12 6 ~0 Christian 8 6 14 2 Muslim 2 Non- believers 50 12 2 1 73 Hindu ~0 1 3 32 Other 6 1 4 Buddhist 9 1 1 1 Jewish ~0 ~0 2 ~0 4 SOURCE National Geographic, December 2007
There are many equally valid ways to go to Heaven We rely on our religious texts for moral, emotional and spiritual guidance We rely on science and other intellectual pursuits to gain knowledge about the natural world There need be no conflict in these different There need be no conflict in these different ways of thinking and learning ways of thinking and learning 5
Some preliminary definitions Species individual organisms capable of mating and producing fertile offspring Population a group of individuals of a single species Community a group of individuals of different species Images species, population, community 6
Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 7
Historical Evidence: observed character displacement Changes in beak size recorded over about 2 decades after a natural migration event Photographs by B. Rosemary Grant/Science, 2006 Big-beaked invader Image finches on the Galapagos Resident species shifted to smaller beak size 8
All of agriculture is based on human selection events The domestication of grass ~12,000 years ago Led to the first cultural shift in human civilization Nomadic hunter-gather tribes villages based on agricultural production Other plants and animals as well . Image rice 9
Artificial Selection Brassica oleracea in all its forms Image cabbage, kale, cauliflower, broccoli, Brussels sprouts 10
Farm Animals different breeds Images different breeds of cattle and chickens 11
Cats and Dogs A great dane is the same species as a toy poodle! Images different breeds of cats and dogs 12
The development of pesticide resistance Resistance to insecticides, herbicides, antibiotics .. All natural responses to human generated changes in the environment Diagram development of pesticide resistance due to use of insecticides 13
Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 14
The fossil record extends back BILLIONS of years Images fossils of plants and fish 15
Most form in marine sediments Diagram formation of sedimentary rocks with fossils embedded 16
Fossil substrates can you think of others??? Images other fossil substrates 17
Formation of sedimentary rocks is not uniform in time or space Diagram formation of sedimentary rocks with fossils embedded 18
Critical Thinking The formation of sedimentary rocks is not uniform in time or space Why not??? 19
Critical Thinking The formation of sedimentary rocks is not uniform in time or space Why not??? Dynamic processes! Geological activity Climate Depositional environments 20
Formation of sedimentary rocks is highly dynamic Varies with geological activity Tectonic movements, mountain building, erosion Varies with climate Rain, wind, freeze/thaw cycles, water temperature all affect erosion and sedimentation Varies with the depositional environment Finer sediments in still water, coarser sediments with more wave action or other energy 21
The earths crust is very dynamic Diagram dynamic geological processes: tectonic movements, mountain building, erosion 22
Formation of sedimentary rocks is highly dynamic Varies with geological activity Tectonic movements, mountain building, erosion Varies with climate Rain, wind, freeze/thaw cycles, water temperature all affect erosion and sedimentation Varies with the depositional environment Finer sediments in still water, coarser sediments with more wave action or other energy 23
Climate is naturally dynamic on a geological time scale Graph of benthic carbonates analogous to climate change over the past 5 million years Benthic carbonates parallel atmospheric temperature changes 24
Critical Thinking How could water temperature affect the formation of sedimentary rocks??? 25
Critical Thinking How could water temperature affect the formation of sedimentary rocks??? Limestone is a sedimentary rock that is formed from the tiny shells of marine organisms The abundance of these organisms is partially dependent on water temperature 26
Formation of sedimentary rocks is highly dynamic Varies with geological activity Tectonic movements, mountain building, erosion Varies with climate Rain, wind, freeze/thaw cycles, water temperature all affect erosion and sedimentation Varies with the depositional environment Finer sediments in still water, coarser sediments with more wave action or other energy WHY??? 27
Play with the ocean In high energy environments (waves) only the heaviest sediments can settle Coastal environments produce sandstones In off-shore environments (no waves) finer sediments can settle Off-shore environments produce siltstones, slates, limestones 28
Sediment size depends on the energy level at the site of deposition Diagram of different depositional environments 29
Formation of sedimentary rocks is highly dynamic THUS sediments tend to be deposited in identifiable layers THUS organisms trapped in sediments form a time sequence The earliest organisms are in the bottom layers and the most recent organisms in the upper layers 30
The Grand Canyon a time sequence Image the Grand Canyon showing layers of sedimentary rock 31
Formation of sedimentary rocks is highly dynamic THUS sediments tend to be deposited in identifiable layers THUS organisms trapped in sediments form a time sequence The earliest organisms are in the bottom layers and the most recent organisms in the upper layers Dating these fossils reveals the history of change 32
Study the geological time scale it s the history of life on earth! The geological time scale Use a search engine to find the geological time scale 33
Of course the fossil record is incomplete! Organisms must be trapped in the right place under the right conditions a rare event Fossils must survive geological processes such as subduction, metamorphosis and erosion Fossils must be found! Have you ever found a fossil??? But what we do have is irrefutable evidence of change over time 34
Fossil Evidence Shows Progression Over Time new species . Diagram evolution of elephant lineages 35
.new traits. Diagram limbs developing from bony fins in tetrapods 36
.transitional forms. Diagram transition from bony fins to limbs 37
Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 38
Comparative morphology homologous structures are derived from a common ancestor Diagram forelimbs of various mammals showing identical bone structure with variation in bone size 39
Fish SalamanderTortoise Chicken Pig Cow Rabbit Human Stage of Development Early Diagram similarities in the embryos of a wide variety of vertebrates Later 40 Strickberger, 1996
Comparative morphology vestigial traits Structures that are physically or functionally reduced but clearly similar to functional structures in related organisms Tiny limb bones in some snakes and aquatic mammals Non-flying wings in ostriches emus, kiwis, penguins Blind eyes in cave-dwelling animals Vestigial tails in humans 42
Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 43
Biogeography Darwin observed patterns of species distribution during his voyage on the Beagle Diagram the voyage of the Beagle 44
Sloths found only in South America, even though similar habitats exist on other continents Image modern and fossil sloths 45
Marsupials almost restricted to Australia though convergent evolution has resulted in many similar eutherian mammals on other continents Diagram of marsupial and eutherian mammals showing similar forms Convergent evolution similar traits in unrelated organisms that evolved under similar selection pressures .more later 46
The Galpagos and other volcanic islands Many closely related endemic species .that are similar to those found on the closest mainland Darwin s conclusion species migrated and evolved new adaptations in their new home Diagram of Darwin s finch lineages 47
Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 48
Uniformity and Diversity: same DNA, same ATP, same amino acids, same membranes, same aerobic respiration . Image frog in the center of a bromeliad 49
Critical Thinking What is the implication of this uniformity in the basic building blocks of life, even though there are many millions of organisms both extant and extinct??? 50
