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CHAPTER 22
DESCENT WITH MODIFICATION:
A DARWINIAN VIEW OF LIFE
OBJECTIVES
1. State the two major points Darwin made in The Origin of
Species concerning the Earth's biota.
Darwin’s view of life contrasted sharply with the accepted viewpoint:
the Earth was only a few thousand years old and was populated by
unchanging life forms made by the Creator during a single week.
Thus, On the Origin of Species, not only challenged prevailing
scientific views, but also challenged the roots of Western culture.
The two major points were that 1. Species evolved from ancestral
species and were not specially created and 2. That Natural selection
is a mechanism that could result in this evolutionary change.
2. Describe Carolus Linnaeus' contribution to Darwin's theory
of evolution.
Known as the father of taxonomy, the naming and classifying of
organisms, he developed a system of binomial nomenclature still used
today. The clustering of species in taxonomic groups did not imply
evolutionary relationships to Linnaeus, but id did to other scientists.
7. Describe Jean Baptiste Lamarck's model for how
adaptations evolve.
Lemarck believed that evolution was driven by an innate tendency
toward increasing complexity, which he equated with perfection. As
organisms attained perfection, they became better and better
adapted to their environments. Thus, Lamark believed that evolution
responded to organisms’ felt needs.
11. Explain what evidence convinced Darwin that species
change over time.
Darwin perceived the origin of new species and adaptation as closely
related processes; new species could arise from an ancestral
population by gradually accumulating adaptations to a different
environment. For example, two populations of species could be
isolated in different environments as each adapted to local conditions.
13. Explain why variation was so important to Darwin's
theory.
Variation was important to Darwin’s theory because without it,
natural selection would not be possible.
15. Define and state the basic principles in natural selection.
Natural selection is this differential success in reproduction, and its
product is adaptation of organisms to their environment. Natural
selection occurs from the interaction between the environment and
the inherent variability in a population. Variations in a population
arise by chance, but natural selection is not a chance phenomenon,
since environmental factors set definite criteria for reproductive
success.
17. Using some contemporary examples, explain how natural
selection results in evolutionary change.
Natural selection allows for more frequency of the genes needed by
the individual to survive. Thus, since the genes change and there is a
preference over which ones to get, evolutionary change occurs.
20. Describe how molecular biology can be used to study the
evolutionary relationships among organisms.
An organism’s hereditary background is reflected in its genes and
their protein products. Thus, two species considered to be closely
related by other criteria should have a greater proportion of their
DNA and proteins in common than more distantly related species.
21. Explain the problem with the statement that Darwinism
is "just a theory".
Darwinism is no longer a theory because it has been proven countless
times by fossil records and fields of biology such as biogeography,
comparative anatomy and molecular biology.
CHAPTER 23
THE EVOLUTION OF POPULATIONS
OBJECTIVES
1. Explain what is meant by the "modern synthesis".
Modern synthesis is the focus on populations as units of evolution
2. Explain how microevolutionary change can affect a gene
pool.
Microevolutionary change affects a gene pool by changing allele or
genotype frequencies in an existing population.
3. In their own words, state the Hardy-Weinberg theorem.
Figure 21.3
7. Describe the usefulness of the Hardy-Weinberg model to
population geneticists.
This model would help these geneticists realize the gradual change of
a certain population over time because of little or no change in allele
and genotype frequencies.
9. Explain how genetic drift, gene flow, mutation,
nonrandom mating and natural
selection can cause microevolution.
Each of these examples causes microevolution because they all affect
the allele frequencies of a population. They introduce a change in
alleles or genotypes.
11. Distinguish between the bottleneck effect and the
founder effect.
The bottleneck effect describes a population that undergoes a
dramatic decrease in size. The founder effect describes allele
frequencies in a migrating group differ, by chance, from their
population of origin.
12. Explain why mutation has little quantitative effect on a
large population.
Mutation is not harmful and has no effect in most cases, it is also
adaptive. Mutation is always on a small scale so it could never have a
lasting effect on a large population.
18. Give the cause of nearly all genetic variation in a
population.
Genetic variation is caused by genetic drift, non random mating,
natural selection, mutation and gene flow.
19. Explain how genetic variation may be preserved in a
natural population.
Genetic variation is preserved through diploidy (presence of two
copies of each chromosome) and polymorphism (heterozygous
advantage and frequency dependent selection).
24. Describe what selection acts on and what factors
contribute to the overall fitness of a genotype.
Selection acts on varying characteristics. Overall fitness of a genotype
is accomplished only if a particular genotype has more descendants
than another and selection favors certain genotypes by acting on the
phenotypes of individual organisms.
25. Give examples of how an organism's phenotype may be
influenced by the environment.
Acting on phenotypes, selection indirectly adapts a population to its
environment by increasing or maintaining favorable genotypes in the
gene pool. The overall fitness of a genotype depends on whether its
positive effects outweigh any harmful effects it may have on the
survival and reproductive success of the organism.
26. Distinguish among stabilizing selection, directional
selection and diversifying selection.
28. Give at least four reasons why natural selection cannot
breed perfect organisms.
-Organisms are locked into historical constraints.
-Adaptations are often compromises.
-Selection can only edit variations that exist.
-Not all evolution is adaptive.
CHAPTER 2 4
THE ORIGIN OF SPECIES
OUTLINE
I. What Is a Species?
A. The biological species concept emphasizes reproductive
isolation
B. Prezygotic and postzygotic barriers isolate the gene pools
of biological species
C. The biological species concept does not work in all
situations
D. Other species concepts emphasize features and processes
that identify and unite species members
II. Modes of Speciation
A. Geographical isolation can lead to the origin of species:
allopatric speciation
B. A new species can originate in the geographical midst of
the parent species: sympatric speciation
C. Genetic change in populations can account for speciation
D. The punctuated equilibrium model has stimulated research
on the tempo of speciation
OBJECTIVES
4. Define biological species (E. Mayr).
Biological species is a population or group of populations whose
members have the potential to interbreed.
5. Distinguish between prezygotic and postzygotic isolating
mechanisms.
Prezygotic barrier is a reproductive barrier that impedes mating
between species or hinders fertilization of ova if interspecific mating
is a hempted. Postzygotic barrier is any of several species-isolating
mechanisms that prevents hybrids produced by two different species
from developing into viable, fertile adults.
6. Describe five prezygotic isolating mechanisms and give an
example of each.
There are five different types of prezygotic isolating mechanisms.
Habitat Isolation is when two species that live in different habitats
within the same area encounter each other rarely, for example, two
species of parasites living on different hosts will not have a chance to
mate.
Behavioral Isolation is that special signal that attracts mates, as well
as elaborate behavior unique to a species like male fireflies of
different species signal to females of their kind by blinking their
lights in particular patterns.
Temporal Isolation is when two species that breed during different
times of the day, different seasons, or different years cannot mix
their gametes.
Mechanical Isolation, is when closely related species may attempt to
mate, but fail to consummate the act because they are anatomically
incompatible.
Gametic Isolation is when even if the gametes of different species
meet, they rarely fuse to form a zygote. Gamete recognition may be
based on the presence of specific molecules on the coats around the
egg, which adhere only to complementary molecules on sperm of the
same species.
10. Distinguish between allopatric and sympatric speciation.
Allopatric speciation is a mode of speciation induced when a
geographical barrier segregates the ancesteral population.
Sympatric speciation is a mode of speciation occurring because of a
radical change in the genome that produces a reproductively isolated
subpopulation in the midst of its parent population.
13. Describe the adaptive radiation model and use it to
describe how it might be possible to have many sympatric
closely related species
even if geographic isolation is necessary for them to evolve.
Figure 22.8
14. Define sympatric speciation and explain how polyploidy
can cause reproductive isolation.
Figure 22.10
16. List some points of agreement and disagreement
between the two schools of thought about the tempo of
speciation (gradualism vs. punctuated equilibrium).
One view of speciation is that it usually occurs gradually by an
accumulation of micro evolutionary changes in gene pools. In contrast,
the punctuated equilibrium model views species as changing most
when they bud from an ancestral species and then undergoing
relatively little change for the rest of their existence.
CHAPTER 26
EARLY EARTH AND
THE ORIGIN OF LIFE
OUTLINE
I. Introduction to the History of Life
A. Life on Earth originated between 3.5 and 4.0 billion
years ago
B. Major episodes in the history of life: a preview
II. Prebiotic Chemical Evolution and the Origin of Life
A. The first cells may have originated by chemical evolution
on a young Earth: an overview
B. Abiotic synthesis of organic monomers is a testable
hypothesis: science as a process
C. Laboratory simulations of early Earth conditions have
produced organic polymers
D. Protobionts can form by self-assembly
E. RNA was probably the first genetic material
F. The origin of hereditary information made Darwinian
evolution possible
G. Debate about the origin of life abounds
OBJECTIVES
3. Provide evidence to support the hypothesis that chemical
evolution resulting in life's origin occurred in 4 stages:
a. Abiotic synthesis of organic monomers
b. Abiotic synthesis of polymers
c. Formation of protobionts
d. Origin of genetic information
a. Abiotic synthesis of organic monomers: Through conducting many
experiments, now we know that the atmosphere of early Earth
probably included CO, CO2, and N2, and was less reducing than the
Miller-Urey model, and thus, less favorable to formation of organic
compounds.
b. Abiotic synthesis of polymers: abiotic synthesis and accumulation
of monomers, or small organic molecules, that are the building blocks
for more complex molecules.
c. Formation of protobionts
d. Origin of genetic information
3. Describe Whittaker's five-kingdom system.
Figure 24.10
4. Describe three alternatives to the five-kingdom system
and explain the rationale for each.
Figure 24.10