Department of Biology | College of Arts and Sciences



STUDY GUIDE FOR EXAM 2 - Spring 2021This guide is a checklist of items you should know for Exam 2. They are taken from both the lecture notes and the required textbook readings.Forces that Drive Evolution: Don’t forget these :Recall the five criteria that must be met if a population is to remain in Hardy-Weinberg equilibrium.Remember a population is in Hardy-Weinberg equilibrium with respect to a particular gene/locus, that means the population is NOT EVOLVING at that gene locus. (i.e., genotype and allele frequencies are not changing from one generation to the next at that gene locus)Know the difference between microevolution and macroevolution.Remember what is meant by adaptive, maladaptive, and neutral mutations, and understand how a mutation can have little or no phenotypic effect, or a major phenotypic effect.Remember the difference between silent and neutral mutations. Is a silent mutation always neutral? Why or why not?Also remember that a synonymous mutation is a class of silent mutations.A silent mutation can occur anywhere in the genome, including an exon.A synonymous mutation occurs specifically in a protein-coding region (exon) of the genome.A silent mutation is not necessarily synonymous, but a synonymous mutation is always silent.Lecture 6: Forces that Drive Evolution: Non-infinite Population SizeUnderstand how the Molecular Clock is used to determine genetic distance among sister taxa. (Watch the video at the beginning of lecture 6)What was Motoo Kimura’s contribution to our understanding of evolution? How did his ideas differ from those of Darwin and others who came before?Understand what is meant by the concept of neutral evolution. Recall the differences between neutral, silent, and synonymous mutations.How does gene flow (or the lack of gene flow) affect the evolution of populations?Understand why the rate of evolution in a population can depend on that population’s size.Are small populations or large populations more likely to evolve quickly? Why?Know the meaning and significance of biogeography, and what it can tell us about past evolution.Know the general sequence of events of the breakup of Pangaea. Which of our current continents were once part of Laurasia? Which were part of Gondwanaland? Know what is meant by the terms “Old World” and “New World.Understand how continental drift and island biogeography are related, in terms of speciation of the organisms living on land masses that separate into separate pieces.Understand how the separation of continents and smaller land masses is related to genetic drift.Know the meaning/significance of the following terms, and how they work:Genetic driftinbreedingsampling errorgeneFounder EffectoutbreedinghomozygosityalleleBottleneck Effectfixation of an alleleheterozygositygene poolLecture 7 (and Migration Workshop): Forces that Drive Evolution: MigrationUnderstand the difference between dispersal and migration, and forgive us all for using the term “migration” not quite correctly when it comes to talking about HW equilibrium.Know the meaning/significance of the following terms:demegene flowintrogressionspecies reinforcementfield markimmigrationhybrid zonespecies fusionspecies fusiondemeemigrationhybrid speciationautozygosityhybrid equilibrium/species stabilityBe able to recognize examples of any of the above, even if you’ve never seen them before.Understand the concept of effective population size with respect to the effect of a skewed sex ratio (in breeding adults) on the evolution of a population. Know how to calculate effective population size, and understand the significance of reduced effective population size. How is effective population size different from census population size?In a population with a skewed sex ratio, which sex has greater relative genetic contribution to the next generation, the scarcer or the more abundant sex?Understand how gene flow increases effective size of a population, how lack of gene flow reduces effective population size, and why that matters in real populations.Understand the genetic consequences of small population size. What are possible advantages and disadvantages of homozygosity and heterozygosity in an individual or a population.Understand the meaning/significance of reproductive isolating mechanisms:prezygoticecologicalbehavioralgametichybrid sterilitypostzyotictemporalmorphologicalhybrid inviabilityhybrid breakdownBe able to recognize examples of any of the above, even if you’ve never seen them before.Lecture 8: Forces that Drive Evolution: Non-random matingUnderstand the precise meaning of random mating and non-random mating in a population genetics sense (i.e., in terms of frequency of the types of mating individuals). Remember that the definitions depend on the relative frequencies of mating types in the population.Know the meaning/significance of the following terms:positive (assortative) non-random matingdifferential reproductionnegative (disassortative) non-random matingheterozygosity vs. homozygositysexual selectionautozygositywild type vs. mutantinbreeding vs. outbreedingUnderstand how inbreeding vs. outbreeding relate to non-random mating and small population size. (Think about it.)Does heterozygosity and homozygosity increase or decrease with assortative mating? What about disassortative mating? Understand how assortative mating can cause populations to segregate into effectively smaller populations, thus potentially increasing the rate of evolution.Understand the differences between assortative mating, disassortative mating, and sexual selection. Are all of these forms of natural selection? If so, why? If not, why not? What is the criterion?Lecture 9a: Forces that Drive Evolution: Natural SelectionRemember that while natural selection (and the other five HW factors) may occur at the level the individual organism, only populations evolve. Know the meaning/significance of the following terms:adaptiveoverproductionDarwinian fitnesssympatric speciesmaladaptivecompetitionrelative fitness (W) coefficientwild typeneutraldifferential survivalrelative selection (s) coefficientmutantheritable variabilitydifferential reproduction(^be able to calculate these^)honest signalUnderstand the ramifications of effective population size and a skewed sex ratio in terms of evolution.Recall the meanings of these three aspects of Darwinian fitness, and know what they imply about competing genotypes in a population.progeny survival rate:(N) = Nafter selection / Nbefore selectionrelative fitness (ω) =Ncompeting genotype / Nfittest genotypeselection coefficient:s = 1 - ωUnderstand why a trait that is adaptive in one context may not be in another context. Be able to recognize examples of this concept.In Darwin’s “struggle for existence”, do individuals of the same species compete against each other? Their predators? Their pathogens?Know the difference between a physiological adaptation and an evolutionary adaptation. How are they related to each other?Understand Darwin’s four tenets of evolution by means of natural selection.Is natural selection a hypothesis? Theory? Law? Why?Know the basic principles of the Classical and Balancing Selection models of evolution. Which one explain how alleles can stay in a population even if they are not always adaptive.Understand the concept of evolution as compromise. Why does evolution not result in “perfect” organisms?How does the “selfish gene” figure into the natural selection process? (Think: Building survival machines!)Understand the meaning/significance and be able to recognize examples of: balanced polymorphism, search imagedirectional selectionheterozygote advantage Batesian mimicrydisruptive/diversifying selectionpositive frequency-dependent selectionMullerian mimicry. stabilizing selectionnegative frequency dependent selectionBe able to recognize examples. Lecture 9b (and Sexual Selection Workshop): Forces that Drive Evolution: Sexual SelectionIs there a difference between natural selection and sexual selection? If so, what is it?Understand the concept of sexual selection, and the meaning/significance of: male competition vs. female preference/choice in this phenomenon. What are males competing for? What are females choosing? Why is it more common for females to be the ones choosing their mates, rather than males?What is Bateman’s Principle? What criticisms have been leveled at it? Understand the meaning/evolutionary significance of:intrasexual selectionsexual dimorphismpolygamyintersexual selectionprimary vs secondary sex characteristicspolyandryCinderella effectmate guardingmonogamyagonistic behaviorscryptic estrus (humans) polygynyfemale choicesperm removalinfanticidesperm competitioncopulation pluglekWhat is the Handicap Principle? The Sexy Son Hypothesis?What are the pre-mating and post-mating forms and results of intrasexual selection?What are the pre-mating and post-mating forms and results of intersexual selection?What is meant by “honest signal”? Runaway sexual selection?Recall the species in which male and female expected “roles” are reversed. What are the characteristics of systems like these?Review the workshop material on the Lizards of Ibizia (even if only to watch the video again). Understand the nature of the “sexual arms race”. How can balancing selection operate on traits that benefit one sex, but possibly harm the other?What is intralocus sexual conflict? (If you don’t remember, here’s some help: HYPERLINK "" )Understand what is meant byaltruism (know the specific definition, in evolutionary terms)individual fitnesskin selection (William D. Hamilton’s idea)inclusive fitness“survival machine” (see the videos with Dr. Richard Dawkins) What is meant by the equation R x B > C?TIPS FOR EFFECTIVE STUDYING: 1. Don't memorize the details or names of specific examples or mathematical equations in the notes or text or workshops. Instead, try to understand the concepts those examples are illustrating, and be able to recognize new examples of the same concepts. Memorization is fine for things like vocabulary and names. But the MOST important thing you can do is to UNDERSTAND HOW THINGS WORK and be able to apply this to new situations. 2. Read the textbook chapters and USE THE PRACTICE QUESTIONS AT THE END OF EACH CHAPTER TO TEST YOURSELF. They are an excellent gauge of how well you are actually understanding the material.3. Use Mastering Biology practice quizzes and resources to test yourself.4. If you don’t remember the definition or significance of something in the notes or this study guide…GOOGLE IT.Seriously! This is sometimes the BEST way to find multiple sources that will really help you understand these sometimes-tough concepts. Choose your sources wisely, but learn to teach yourself biology by using the abundant resources available at the touch of a key. ................
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