Download Chapter 15—Evolution I. Section 1:Darwin`s Theory of

Chapter 15—Evolution
I. Section 1:Darwin’s Theory of Natural Selection
- ____________ developed the Theory of Evolution based on Natural Selection.
A. Darwin on the HMS Beagle (1831)
- surveyed the ____________ ____________ coast
- the trip took __ years
- Darwin’s role on the ship was as ____________ and companion to the captain.
- His job was to collect ____________ and ____________ specimens during the ship’s travel.
- Darwin dropped out of ____________ school and then went to ____________ and graduated with a
theology degree.
- Darwin was influenced by others:
*____________ wrote the Principles of Geology which said that the Earth was ____________ of years
old.
*____________ did population studies which said that humans ____________ offspring and things like
war, famine and disease keeps the population in check (referred to as competition for resources.
B. The Galápagos Islands
- Darwin studied ____________ ____________ (selective breeding) techniques
- Darwin began to collect mockingbirds, ____________, and other animals on the four islands.
- He noticed that the different ____________ seemed to have their own, slightly different
____________ of animals.
C. Darwin's Theory of Natural Selection
- Almost ____________ specimen that Darwin had collected on the islands was ____________ to
European scientists.
- Populations from the ____________
changed after reaching the Galápagos.
- Darwin Continued His Studies
- Darwin hypothesized that ____________
____________ could appear gradually
through ____________ changes in ancestral
species.
- Darwin inferred that if ____________
could change species by artificial selection,
then perhaps the same process could work in
____________.
- 4 Basic Principles of Natural Selection:
1. ____________ in a population show ____________.
2. Variations can be ____________.
3. Organisms have ____________ offspring than can ____________ on available resources.
4. Variations that ____________ reproductive success will have a greater chance of being
____________ on.
- Given enough ____________, Natural Selection can modify a population enough to produce a
____________ ____________.
D. The Origin of Species
- Darwin ____________ On the Origin of Species by Means of Natural Selection in ____________.
- Darwin was forced to publish the book.
- Darwin’s theory of ____________ ____________ is not the same as ____________.
- ____________ is the cumulative changes in groups of organisms over time.
- ____________ ____________ is the mechanism by which evolution occurs.
II. Evidence of Evolution
- Darwin's book showed how evolution ____________ happen.
- Also provides ____________ that evolution has occurred.
- Theory states that ____________ organisms on Earth have descended from a ____________ ancestor.
A. Fossil Record
- Provides a ____________ of species that lived long ago.
- Important source of information for determining ancestry and ____________ of evolution.
- Contains lots of ____________ ____________
which contain features shared by different species
*for example: Archaeopteryx had ____________
like birds and teeth and bony tails like
____________.
- The ancient Glyptodont have been compared to
modern day ____________.
- ____________ ____________ are newly
evolved features, such as feathers, that do not
appear in the fossils of common ancestors.
- ____________ ____________ are more primitive features, such as teeth and tails, that do appear in
ancestral forms.
B. Comparative Anatomy
1. Homologous Structures
- Anatomically ____________ structures inherited from a common ancestor. ex: arms of
vertebrates
2. Vestigial Structures
- ____________ that have ____________ function that indicate a change in the organism over
time
- ____________ ____________ predicts that features of ancestors that no longer have a function
for that species will become smaller over time until they are lost.
- Not all anatomical structures indicate ____________ ancestry
3. Analogous structures can be used for the ____________ purpose and can be superficially
____________ in construction, but are not ____________ from a common ancestor.
- Show that functionally ____________
features can evolve ____________ in
similar environments
C. Comparative Embryology
- Vertebrate ____________ (early pre-birth stage
of vertebrates) exhibit homologous structures
during certain ____________ of development
but become ____________ different structures in
the adult forms.
- Embryo's are ____________ and indicate a ____________ ancestry.
D. Comparative Biochemistry
- Common ancestry can be seen in the complex metabolic ____________ that many different organisms
share.
- comparison can be made between ____________ ____________ sequences in proteins
- the more closely related organisms are the ____________ ____________ there will be in amino acid
sequences
- Conversly, the more ____________ the relationship between two organisms, the ____________ the
difference in the amino acid sequence.
- Comparisons of the similarities in these ____________ across ____________ reflect evolutionary
patterns seen in comparative anatomy and in the ____________ record.
- Organisms with ____________ related morphological features have more closely related
____________ features.
E. Geographic Distribution
- Organisms (like finches) that live in South America will be more ____________ to each other than the
organisms living in ____________ environments in Europe
- The distribution of ____________ and ____________ that Darwin saw first suggested ____________
to Darwin.
- Patterns of ____________ were critical to Darwin when he was developing his theory.
- Evolution is intimately linked with ____________ and geological forces.
- ____________ is the study of the distribution of plants and animals on the Earth.
F. Types of Adaptation
- An ____________ is a trait shaped by natural selection that increases an organism’s reproductive
____________.
1. ____________ is a measure of the relative contribution an individual trait makes to the next
generation.
2. Camouflage
- Allows organisms to become almost ____________ to predators
3. Mimicry
- One species evolves to ____________
another species.
4. Antimocrobial Resistance
- the development of a resistance to
____________ by bacteria
III. Shaping Evolutionary Theory
Mechanisms of Evolution
- evolution occurs at the ____________ level not the ____________ level.
- there are a number of different ways evolution can occur.
A. Genetic Drift
- A ____________ in the allelic frequencies in a population that is due to ____________
- In ____________ populations, the effects of genetic drift become more pronounced, and the chance of
____________ an allele becomes greater.
- for example, a flood occurs and wipes out all but 5 animals that happen to be in the top of a tree--only
their alleles are passed on
1. Founder Effect
- example of ____________ genetic drift
- Occurs when a ____________ sample of a population settles in a location ____________ from
the rest of the population
- Alleles that were ____________ in the original population might be ____________ in the new
population.
- for example, 2
lizards are blown
off-shore to an island
2. Bottleneck
- another example of
genetic drift
- Occurs when a
population
____________ to a
very ____________
number and then
____________
- ____________
diversity
- for example, cheetahs
B. Gene Flow
- migration
- ____________ genetic variation within a population and ____________ differences between
populations
C. Nonrandom Mating
- choosing mates
- Promotes ____________ and could lead to a
____________ in allelic proportions favoring individuals
that are homozygous for particular traits
D. Mutation
- ____________ changes in DNA
- some ____________, some bad
E. Natural Selection
- Acts to ____________ the individuals that are
____________ adapted for survival and reproduction
1. Stabilizing selection
- most ____________ form of natural selection
- operates to ____________ extreme expressions of a trait
when the average expression leads to ____________ fitness.
2. Directional selection
- makes an organism more ____________
- favors selection of ____________ versions of a trait
- example is peppered moth
3. Disruptive selection
- a process that ____________ a population into two groups
- favors individuals at the ____________ ends of a trait
4. Sexual selection
- ____________ in frequency of a trait is based on the ability to ____________ a mate
- operates in populations where males and females differ significantly in ____________.
- Qualities of sexual attractiveness appear to be the ____________ of qualities that might enhance
survival.
F. Reproductive Isolation
- only members of the ____________ species can breed
- ____________ is the process by which some members of a population change so much that they can
no longer produce fertile offspring
- there are two mechanisms by which speciation can occur
1. ____________ ____________ prevents reproduction by making fertilization unlikely.
-for example, organisms don't have ____________ range,
have different songs or breed at different times
- ____________ genotypes from entering a population’s
gene pool through geographic, ecological, behavioral, or
other differences
(picture) Eastern meadowlark and Western meadowlark
2. ____________ ____________ occurs when
fertilization has occurred but a hybrid offspring cannot
develop or reproduce.
- Prevents offspring survival or ____________
- The offspring of a male lion and a female tiger is a liger. Ligers are sterile.
G. Speciation
- results in ____________ species
1. Allopatric Speciation
- A ____________ barrier divides one population into ____________ or more populations.
- The Grand Canyon is a geographic barrier separating the Abert and Kaibab squirrels.
2. Sympatric Speciation
- A species evolves into a ____________ species ____________ a physical barrier.
- The ancestor species and the new species live ____________ by ____________ during the
speciation process.
H. Patterns of Evolution
1. Adaptive Radiation (Divergent Evolution)
- can occur in a relatively ____________ time when one species gives rise to many
____________
species in
response to the
creation of
____________
habitat or some
other ecological
opportunity.
- Follows large-scale ____________ events
2. Coevolution
- The ____________ between two species might be so close that the evolution of one species
____________ the evolution of the other species.
Examples are:
____________- which occurs when two species benefit from each other
________________________ ____________ ____________-which is when one species evolves
a parasitic dependency on another species.
3. Convergent Evolution
- ____________ species evolve similar traits because they ____________ in similar
environments in different parts of the world.
4. Rate of Speciation
- Evolution proceeds in ____________, gradual steps according to a theory called
____________.
- ____________ ____________ explains rapid spurts of genetic change causing species to
diverge quickly.
Shaping Evolutionary Theory