Download Biology 182: Study Guide I Introduction

Biology 182: Study Guide I
PART I. PATTERNS & MECHANISMS OF EVOLUTION: Chapters 22-25
Tentative Exam Date: 05 February 2008
Introduction
This study guide provides a checklist of terms, concepts and topics covered in Bio 182. Although
arranged by chapters from your text, topics may be presented at various times in lecture, lab, or
both.
This guide is not exhaustive. Use this guide with your lecture & laboratory notes, and your text,
to create your own set of working notes for study.
This guide will also help you identify concepts that need further clarification. For additional
review, answer the questions at the end of each chapter in your text; additional review is
available on the CD that comes with your textbook. Also, search on the internet using terms and
vocabulary pertinent to evolutionary concepts covered herein; reading and seeing from different
perspectives should enhance your understanding and learning.
The best way to succeed in this class is to devote consistent and considerable time to studying
and thinking. (1) First, you should read the next lecture topic(s) BEFORE coming to class; at
least acquaint yourself with what is coming. That way lectures will not seem foreign and beyond
all understanding. (2) Next, you should listen carefully in lecture and lab, take thorough notes,
and ask questions when you do not understand, or if you are just curious about something. (3)
Third, you should study those notes and topics THE SAME DAY while the information is fresh
in your minds. Make flashcards to review topics and memorize information. Take a flashcard
out of the stack when you have learned the information on it; don’t waste your time reviewing
what you already know. (4) Fourth, you should answer the objectives and questions on the
study guide immediately after memorizing and understanding topics. Ultimately, you should
be able to answer all questions WITHOUT referencing your notes or book. (5) Fifth, you
should study with others, testing each other and answering each other’s questions. Finally,
when the time arrives to take a lecture exam, you should relax and feel satisfied that you have
done everything that you can to prepare. Just do your best, and if you have followed my
guidelines, you should pass, and hopefully you will get an “A” or “B”.
Chapter 22. Descent with Modification: A Darwinian View of Life
This chapter introduces the theory of evolution by natural selection, from the philosophical roots
of western culture to the presentation of Darwin’s book, ‘The Origin of Species’. The end of the
chapter includes recent evidence that further supports evolution. You should be able to identify
some of the most important researchers in this field, and their contributions to our understanding
of evolution.
Objectives for Chapter 22:
1. Below is a list of names and terms or concepts, many of which are associated with specific
names. Be able to identify or list these names and terms. Be able to define or explain the terms
and concepts.
Plato: idealism / essentialism
Aristotle: scala naturae (scale of nature)
Linnaeus: taxonomy, natural theology
Cuvier: catastrophism
Hutton: gradualism
Lyell: uniformitarianism
Lamarck: use and disuse, inheritance of acquired characteristics
Darwin : evolution by natural selection
Wallace: independently hypothesized evolution by natural selection
Malthus: struggle for existence
2. Explain how fossil evidence and new theories in geology set the stage for Darwin’s theory;
how did previous studies influence Darwin in his thinking?
3. Be able to explain why biologists consider Darwin’s version of evolution as both a fact and a
theory. What do scientists mean when they call an idea a ‘theory’?
4. Be able to recite and describe the five observations and three inferences that make up the
theory of natural selection as summarized by Ernst Mayr.
5. According to Darwin’s theory, what is the smallest unit of life that can evolve? Explain.
6.
What is ‘artificial selection’? Provide at least 2 examples. How did it influence Darwin?
7. Describe one example from your text that suggests natural selection in a living population.
8. Summarize the evidence from each of the following disciplines that suggests evolution has
occurred:
Define homology. Then, in the context of homology, discuss: comparative anatomy,
comparative embryology, molecular biology
Explain how biogeography and fossils/paleontology each provide support for the
theories of evolution and common ancestry, respectively.
Chapter 23. The Evolution of Populations (microevolution)
This chapter opens with a brief description of ‘the modern synthesis’, then focuses on
microevolution with use of the Hardy-Weinberg Equilibrium (HWE). It closes with discussions
of genetic variability and the limits of natural selection.
Objectives for Chapter 23:
1. Explain why early evolutionary biologists and geneticists were at conflict and how that
conflict was resolved (the modern synthesis). As part of your discussion, define population
genetics.
2. Define and differentiate among population, species, and gene pool. Why might a population
be difficult to objectively identify in nature? What does it mean for a specific allele to be
fixed in a population?
3. The Hardy-Weinberg theorem (HWT) provides a model for describing or modeling a
nonevolving population. State the Hardy-Weinberg theorem. List or identify the five
assumptions of this model and their five counterparts, the possible mechanisms of evolution.
Which of these mechanisms is/are expected to adapt a population to its environment?
4. Explain how the HWT “plugs a hole in Darwin’s theory of natural selection” with respect to
genetic variation.
5. Understand and be able to use the formulas of the Hardy-Weinberg equilibrium (including
the “Hardy-Weinberg equation” to determine the current allelic and genotypic frequencies of
a population, and from these data the expected allelic and genotypic frequencies of
subsequent generations (See especially Figure 23.5). How could you tell that a population
is in Hardy-Weinberg equilibrium or not?
Sample question:
Show mathematically and describe in evolutionary terms why the HWE predicts:
a parental population with: p = 0.6 and q = 0.4 should give rise to offspring
with these genotypic frequencies: AA = 0.36, Aa = 0.48, aa = 0.16
6. Be able to define, describe and use the following terms:
population
gene pool genetic drift bottleneck effect founder effect gene flow
inbreeding assortative mating polymorphism
cline
hybrid vigor
balanced polymorphism frequency-dependent selection fitness
7. Define microevolution (the definition of evolution at the population level). Compare and
contrast this definition with that of Darwin’s for evolution (“descent with modification”).
8. Compare and contrast the bottleneck effect and the founder effect, as they relate to genetic
drift. Provide at least one example (real or imaginary) for each phenomenon.
9. Describe the effect(s) different levels of gene flow might have on the genetic structure of
populations.
10. Describe the importance of mutation to evolution. Is mutation by itself a powerful
evolutionary mechanism? Why or why not? How might translocations or duplications be
beneficial (i.e., under what circumstances)?
11. Which mechanism, mutation or sexual recombination, is more important for producing
genetic variation from generation-to-generation? What are the various sources of genetic
recombination?
12. Explain the importance of genetic variation to evolution by natural selection. Differentiate
between quantitative and qualitative characters.
13. Describe how genetic variation is measured. How much genetic variation exists in natural
populations (describe some examples)?
14. Describe how variation is preserved in a population. Define and use the terms diploidy,
balanced polymorphism, heterozygote advantage, and frequency-dependent selection in your
answer.
15. Describe the theory of neutral evolution, and describe any “problems” with interpreting
variation as neutral.
16. Compare and contrast Darwinian fitness and relative fitness. Explain how survival and
fertility interact and contribute to fitness. Identify the ultimate target of natural selection, and
justify your answer.
17. Compare and contrast directional, diversifying, and stabilizing selection. Draw or identify a
graph that represents each effect of selection.
18. Describe at least two hypotheses for the evolution and persistence of sexual reproduction.
Under what circumstance(s) would asexual reproduction be more advantageous?
19. Define sexual dimorphism. Name the theory that explains sexual dimorphism. Compare
and contrast intra- and intersexual selection. Explain how sexual selection relates to
nonrandom mating (one of the conditions necessary for Hardy-Weinberg equilibrium).
20. List and describe four reasons why natural selection cannot fashion perfect organisms.
Chapter 24. The Origin of Species (speciation)
Both Ernst Mayr (a prominent evolutionary biologist) named 137 bird species in the Arafak
Mountain of New Guinea, and the native people independently named 138 bird species in the
same area. They identified each species by their difference(s) in appearance, and this method of
naming species is identical to that of Linnaeus. This suggests our ideas of species has some
reality!
This chapter addresses the species question: What is a species and how do new species arise?
Scientists have provided a variety of answers to both of these questions. Moreover, most of
these explanations are not exclusive. This subject matter provides some of the best examples of
how difficult it is to pigeon-hole life! You should focus on the different hypotheses for each
question, the evidence associated with these hypotheses and their problems, and the general
overlap between these hypotheses.
Objectives for chapter 24:
1. Contrast anagenesis to cladogenesis.
2. Define the Biological Species Concept (BSC). Name the person largely responsible for this
idea. Provide an example and explain how this concept would be used to identify different
species.
3. List and describe both prezygotic and postzygotic barriers to successful reproduction.
Explain how any of these barriers might be sufficient to maintain species boundaries.
Provide an example of a prezygotic and postzygotic barrier, respectively (see pgs. 474-475).
4. List and describe several limitations to the BSC.
5. List and describe some of the alternative species concepts to the BSC. What fundamental
concept or idea do most of these have in common?
6. Compare and contrast allopatric and sympatric speciation. Describe conditions necessary for
allopatric speciation to occur. Explain how ring species (e.g., Ensatina) show different
stages of speciation.
7. Define adaptive radiation, and explain how patterns of adaptive radiation support the
allopatric speciation model.
8. Compare and contrast autopolyploids and allopolyploids, and explain how each may
represent new species by sympatric speciation. Using the examples of Rhagoletis and Lake
Victoria cichlids, explain how sympatric speciation in animals may occur.
9. What observations does the theory of punctuated equilibrium explain? What is the theory of
punctuated equilibrium? Why are those two words (“punctuated” and “equilibrium”) used as
a name for this theory? Under this theory, what period of time might be considered rapid for
the origin of a new vertebrate (e.g., mammal) species?
10. Define macroevolution, and differentiate it from microevolution (previously discussed).
Provide an example of macroevolution that shows the transition from a relatively simple to a
relatively complex structure (e.g., the “eye” of mollusks). Define exaptation, and explain
how exaptations may allow adaptive radiations to occur. Provide an example.
11. In regards to evolution by modification in the development of an organism: Define
allometric growth and heterochrony, and explain how each of these phenomena can account
for seemingly significant differences between species. Provide an example of each. Define
paedomorphosis and explain how heterochrony may produce this effect; provide an example.
Explain what Hox genes are, and how they influence development of major morphological
structures.
12. Evolutionary patterns are bushy rather than straight and linear. How does this pattern reject
the idea that evolution is progressive or goal-oriented (refer to the evolution of horses)? Is
natural selection goal oriented? Why or why not? Define species selection, and explain how
this process (if it occurs) is analogous to natural selection within a population.
Chapter 25. Phylogeny and Systematics.
This chapter introduces fossils and the methods of paleontologists, presents the Geologic Time
Scale and methods for dating fossils. It reviews how major geologic events (e.g., plate tectonics)
have affected the distributions and evolution of life, and the causes of mass extinctions in the
past. The science of systematics is reviewed, including how we name and classify life
(taxonomy), and how we explain the evolutionary relationships among species or groups of
species (phylogenetics).
Objectives for Chapter 25:
1. Describe in general terms how fossils form (e.g., processes of sedimentation, mineralization,
etc.), and describe the different types of fossils (e.g., imprints, casts, trace, mineral
replacement, etc.).
2. Explain why the fossil record “slanted” towards representing some groups of species more
than others.
3. Define systematics. Compare and contrast taxonomy and phylogenetics. In reference to
taxonomy, explain and use the term binomial, and list the major categories of hierarchical
classification proposed by Linneaus (and still used today).
4. Define homology and explain how the concept is used in phylogenetics. Is the rate of
morphological divergence consistent with the rate of molecular (DNA) divergence? Why or
why not (see silversword example). What are homoplasies? Provide an explanation for their
existence. How might homologies be distinguished from homoplasies?
5. In reference to phylogenetics, outline or list the steps of cladistic analysis. Along the way,
define and properly use the terms cladogram, homology, convergent evolution, shared
derived characters, shared primitive characters, outgroup, ingroup, monophyletic,
paraphyletic, polyphyletic, clade. Contrast phylograms and ultrametric trees.
6. Contrast the methods of maximum parsimony and maximum likelihood. What are the
assumption of each method? How might these assumptions be violated / broken?
7. Explain why phylogenetic trees are considered hypotheses, and how the ‘best’ hypothesis is
chosen.
8.
What factors contribute to molecular systematics elucidating evolutionary relationships for
both distantly related and closely related species? Which parts of our genome, respectively,
would be used for inferring long- or short-term relationships?
9. Compare and contrast orthologous and paralogous genes. Which can only diverge after
speciation has taken place, and why?
10. Explain how the concept of molecular clock is used to infer time since divergence from a
common ancestor. How does neutral theory relate to practical use of a molecular clock, and
what are some of the difficulties with molecular clocks?
11. Describe the evidentiary basis for the universal tree of life hypothesis. How many Domains
of life are recognized, what are their names, and what is the basis of recognizing them as
separate taxonomic groups? Explain why the early history of these domains is not yet clear.