Download evolution notes - bio 520

Evolution and the history of life - Chap 16-19 - student notes
Make sure your check out the evolution links for lots of background info | Check out this site for
an excellent overview of evolution | Also check out the PBS evolution site for lots of good basic
info | evolution animations
I. Definitions: (click for more details)
1. Change over time
2. the Big Bang - theory that explains how the universe was created (how it
happened, not why or who) (this theory in no way conflicts with Genesis, but for
some reason a lot of people think it does) (how do we know how big the universe
is??)
3. Origin of life (how it started, not how it has evolved since)
4. Natural selection - theory that explains how species can change over time in
response to environmental changes; involves survival of the "fittest" individuals
or genes
5. Common descent - theory that all living things share a common ancestor presumably a one-celled creature of some sort. It is usually postulated that new
species arise over time through natural selection, and that over very long periods
of time the vast diversity of living things was produced. (click here for the latest
version of the "tree of life")
6. Evolutionism (evolutionary philosophy) is a belief that physical explanations
provide all of the answers about life; that there is no God. (similar to atheism or
naturalism)
7. Social darwinism is a belief that "survival of the fittest" should be applied to
society, and that we should not allow "weaker" or "inferior" members to
reproduce. It is not believed by many people today, although it was widely held in
the early 1900's.
II. Evidence for Common Ancestry | check out evidence for evolution | plus all the links
below
Common descent: the theory that all creatures are descended from a common ancestor. (This
theory is not the same thing as natural selection and was not invented by Darwin)
A preview of the Categories of Evidence:
A. Fossils and the history of life
B. Biogeography patterns
C. Similarities between creatures
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Darwin's predictions - evidence for common descen
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Chris Colby's "Evidences for Evolution"
A. Fossils and the history of life – p. 542-543 and chap 19
1. life has changed over time - we can tell by interpreting the fossils
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a brief history of life
the Tree of life
2. how are fossils formed and interpreted?
a. formation - rapid burial in sand, mud, tar, etc. Hard parts are
most often preserved; also impressions of soft parts (see p. 540,
fig. 19-2; also 19-3)
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more background info on fossils
amber (link to NOVA website: Jewel of the Earth)
b. dating the fossils
· relative dating (position in rock layers; fig 19-3, p.
540)
· radioactive dating (p. 541, fig 19-4)
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Overview of geologic time
another overview
animated explanation
another animated explanation
Radiometric Dating: a Christian Perspective
c. studying the fossils involves careful comparison of various
features
3. geologic periods - the time table gives us a general progression of when
different species lived when went extinct. (p. 542, fig 19-5)
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Animated timeline of the history of life
Timeline with illustrations of sample creatures
Triumph of Life - timeline with photos of representative creatures
Geological time machine -- links to details on geological eras
Timeline with emphasis on evolution
Major events in the history of life (interactive)
History of the universe (interactive)
4. Continental drift
5. most major complex kinds of animals (phyla) appeared early and have changed
little since that time. This happened during the so-called "Cambrian explosion".
(scroll down to learn more; see p. 560)
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drawings of Burgess Shale fossils from the time of the
Cambrian Explosion
more on the Burgess shale
6. there have been 5 major extinctions, but the overall diversity of life has
increased - p. 548
7. "transitional forms" between major groups - see fig 16-13 for an example (p.
466-467)
a. there is some debate about how common transitional species are
b. examples of some transitional forms
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overview of the fossil record
Transitional Fossils section of the Talk Origins site
overview of 5 significant transitional fossils
fossil mammals
a discussion of the transition from fish to amphibians
The Illinois State Museum has a good site that explains
the effect of the ice ages on recent extinctions. They also
have pictures of extinct mega-mammals from before the
last ice age.
Fossil Horses in Cyberspace -- pictures/info on horse
fossils
Paleontology museum at Cornell -- check out images and
information on invertebrate fossils.
hind legs on a whale | more on whale origins (Nov 2001
Nat. Geographic)
origins of bird flight
Compare modern humans with Neanderthals | The famous
"Piltdown man" hoax
simulations of dinosaurs and other prehistoric life
(interactive site from BBC)
4-winged dinosaur - a possible dinosaur/bird transition
view an animation of the Cambrian explosion
Fossils at Dinosaur National Monument
Dinosaurs: Fact and Fiction (from USGS)
B. Biogeography - see p. 465
1. definition: study of the differences between similar species in differing
geographic locations
2. species on islands differ from those on mainland
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Madagascar | another site | new tree species
Galapagos (another site)
Hawaii
Australia and New Zealand
Island species are often smaller or larger than their mainland
counterparts | more here
Catalina Island, southern CA
3. species on one side of a continent differ from those on the other side (example white-tail deer and mule deer)
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more info
4. species on different continents are different, but fossils show that species on
different continents used to share the same range. (ties in with continental drift)
· plants in Australia, South America, Africa, and Antarctica
· fate of marsupials on South America
Examples of speciation based on biogeography (some new species have evolved,
but this does not necessarily prove common descent of all creatures):
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Cichlid fish in Lake Victoria
more listed with the natural selection section
C. Similarities between creatures
1. extensive similarities are often found between limbs or organs of similar
creatures (fig 16-14)
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check out these comparisons of human and gorilla skeletons
similarities between limb bones of tetrapods
compare wolves, dolphins, and fish
compare the skeletons of humans with chimpanzees and extinct homonids
2. homology and analogy (click for a good explanation)
a. homologies are structures that share a common origin but not
necessarily a common function
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examples: reptile jawbone and mammal inner ear bones;
and the swim bladders and lungs; “animal hands”
onvergent evolution (analogous structures develop more
than once)
Examples of convergent evolution | the Tasmanian "tiger"
postulated ancestry of whales (more here)
3. comparison of protein sequences and DNA sequences between various
organisms - p. 470; fig 16-16
a. similarities often parallel the anatomical similarities – human
proteins are more similar to monkeys than to lizards, for example.
b. pseudogenes, gene duplication and divergence, and exon
shuffling help explain genetic changes
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"pseuodgenes" and other genetic sequences | more
exon shuffling
example
gene duplication
29+ evidences for macroevolution (good overview, lots of
examples and diagrams)
c. The rate of mutation can be used as a “molecular clock”
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it is assumed that mutations happen at a regular rate, and
thus the number of differences between two genes (in
different species) tells how long ago they shared a common
ancestor
4. Patterns of development
a. development is the process of growth from fertilization to adult.
It usually refers to animals.
b. patterns are often similar in the early stages. Structures not
found in the adult will appear and then disappear. (note examples
below)
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vestigial structures, such as the pelvis in whales (see fig 16-15 skinks)
pharyngeal "gill slits"
c. recently, evidence has shown that small genetic changes can
cause major developmental changes, and might help explain the
formation of new species with new features. For examples, see:
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Learn more about the relationship between evolution and
development
III. Natural Selection - chap 16
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first proposed by Charles Darwin in 1859 in "On the Origin of Species", and also by
A.R.. Wallace around the same time (Darwin’s voyage – p. 450-453)
A. The theory is based on several observations about the way the creation works: | check out this
background activity: how evolution works | text p. 462, fig 16-10
1. overproduction of offspring
2. competition for limited resources
3. individual variation - some individual have genes/traits that allow them to
survive longer, sometimes called adaptations (see p. 461, fig 16-9; also 16-17 and
16-18; 17-4)
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example - snails
there is considerable debate about whether mutations can be helpful
As a result of these three situations, the following results:
4. the individuals with the "better" traits will live longer, have more offspring, and
pass on their traits - fig 16-10
5. over time, the frequency of the favored trait increases - see fig 16-18 and
evolution lab.
B. a few definitions/concepts:
1. speciation refers to the process of a new species being formed | more here evidence for how speciation works | and here - basic overview - see fig 17-13
2. adaptive radiation refers to the development of several new species from a
common ancestor after colonization of a new area, or after a major extinction (see
fig. 19-11 p. 550)
3. in order for new species to form, the population usually must be separated into
two groups. Over time, they evolve differently, until they can no longer
interbreed. Reproductive isolation may be caused by (see p. 494-495):
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sexual selection -- preference for size, color, etc.
o the Irish elk -- huge antlers considered an example
of "runaway sexual selection"
parasites
timing of mating
size/shape changes
hybrid sterility
changes in chromosome number (examples - tree frogs and
plants)
Check an illustrated explanation of how new species can form - this is called
allopatric speciation
4. many scientists propose that the environment plays a significant role in the
evolution of species, especially in the case of mass extinctions (such as the
asteroid that may have killed off the dinosaurs; also a mass extinction at the end
of the Permian period)
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debate on the tempo of evolutionary change – p. 549, fig 19-10
C. Examples of Natural Selection
1. Examples that do not involve new species:
a. industrial melanism – moths in England – (check out why this is
a good example)
b. pesticide resistance (more)
c. antibiotic resistance (view animation of this process and another
animation)
d. sickle-cell anemia
e. changes in salmon size as a result of fishing
f. forest vs. savanna elephants
g. the multiple varieties of dogs are a results of artificial selection
many examples involve co-evolution, where one species evolves in
response to another | more on co-evolution
2. examples involving formation of new species (speciation)
a. Cichlid fish in Lake Victoria
b. shell fish in inter-tidal zones
c. rainforests – adaptive radiation of insects, rodents, etc.
d. arctic char in an Iceland lake
e. plants
f. observed examples of speciation -- talk.origins faq
g. directional vs. stabilizing selection
h. species on islands are often larger or smaller than their mainland
counterparts
i. salamanders in California - how this works)
j. finches in Galapagos
k. animation of natural selection
3. some changes do not result from natural selection – p. 490
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genetic drift
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bottleneck – fig. 17-8
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founder effect
4. other aspects of evolutionary change
a. evo-devo: developmental changes can drive major evolutionary changes. More
here.
b. Does evolution have goals?
c. scientists debate the pace of evolutionary change by comparing the gradualist
and punctuated equilibrium models (more below under "fossil evidence")
D. The gene pool of non-evolving populations remains constant over time -- see p. 491-492 Hardy-Weinberg equilibrium
E. Natural selection can shift gene frequencies in three ways -- see p. 487-489, fig 17-7 and 17-6
1. Stabilizing selection
2. Directional selection
3. Diversifying selection
II. History of life - some relationships - chapter 19 | see BBC's gallery of prehistoric life |
walking with prehistoric beasts | more links below
A. examples of some transitional forms
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overview of the fossil record
Transitional Fossils section of the Talk Origins site
overview of 5 significant transitional fossils
fossil mammals
a discussion of the transition from fish to amphibians
The Illinois State Museum has a good site that explains
the effect of the ice ages on recent extinctions. They also
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have pictures of extinct mega-mammals from before the
last ice age.
Fossil Horses in Cyberspace -- pictures/info on horse
fossils
Paleontology museum at Cornell -- check out images and
information on invertebrate fossils.
hind legs on a whale | more on whale origins (Nov 2001
Nat. Geographic)
origins of bird flight
Compare modern humans with Neanderthals | The famous
"Piltdown man" hoax
simulations of dinosaurs and other prehistoric life
(interactive site from BBC)
4-winged dinosaur - a possible dinosaur/bird transition
view an animation of the Cambrian explosion
B. Modern species are not considered ancestors of other modern species.
C. Fish appear in the fossil record before other vertebrates. They are presumably
ancestors of other vertebrates
D. The first 4-legged creatures (tetrapods) were amphibians
E. Reptiles appear next. Birds, dinosaurs, modern reptiles, and mammals are all
considered descendents of extinct reptiles.
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click here for the latest version of the "tree of life", as proposed by
common descent theory)
basic overview of evolutionary "family trees"
What is a dinosaur?
UCMP Berkeley -- paleontology museum: the history of evolution
(Darwin was not the first one to talk about it!) | overview of the latest
theories about relationships between organisms (a family tree of sorts) |
The Cambrian Explosion refers to the simultaneous appearance of most
major animal phyla, including fossils from the Burgess Shale
Human evolution - compare a human skull to H. Florensis, the "hobbit"
fossil found recently in the South Pacific | more on the Floris fossils
Human evolution - gallery of fossil evidence | overview from PBS |
overview from Evolution 101 | More on human evolution
E. Most paleontologists believe that birds evolved from a group of dinosaurs called
Theropods
How will life evolve in the future? Check out the Future is Wild
Interpreting Evolution from a Christian perspective
I. God’s revelation to us comes in two forms
A. General revelation – the creation (see Ps. 19:1-4)
B. Special revelation – the Bible
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These two forms of revelation cannot disagree. When there are apparent
disagreements, they result from our theology or our science being wrong.
II. God works in two ways
A. Supernatural (miracles)
B. Natural
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we must view God’s action in both natural and supernatural – in
opposition to Deism
God is creator and sustainer (see Ps. 104:27-30)
III. Christians have taken several approaches to resolving the conflicts.
A. overview of seven different positions
B. Young-earth creation
C. Old-earth creation/Progressive creation
D. Theistic evolution/evolutionary creation
E. Intelligent design
IV. Framework approach to understanding Genesis 1
A. God forms on days 1-3 and fills on days 4-6
B. The progression of events is not necessarily literal – it was written to inform us
about the nature of God’s creation and our relationship to the rest of it