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1 Population Biology, Test 1. Name Population Biology, Test 1. name _____________________ •Most people will finish well before the 75 minutes are up, but those few who don't may without speaking follow me to the room next to my office where more time will be provided. If you want to use my dictionary or to say something to me, raise your hand. •Be very careful to not even look like you are peaking at other people's tests or your notes. If you even look suspicious I'll have to move you and it's disruptive. Also, the sequence of questions is different on neighboring tests, so you won't get very far cheating even if you try. •Don't worry tonight if you were unable to answer every question. This is a hard test meant to allow great students to show their stuff, but the grading system is lenient. You can miss quite a few questions and still get an okay grade. When two or more answers seem possible to you, I suggest guessing among them and moving on. 1. Populations that have plenty of resources a. are at carrying capacity. b. grow arithmetically (linearly). c. grow exponentially (geometrically). d. have discrete generations rather than continuous generations. e. are at Hardy-Weinberg equilibrium. 2. The study of quantitative trait loci (QTLs) a. is bringing together the ecology of population growth (focusing on N) and the study of population genetics (p's and q's). b. is a way of showing that hitchhiking has occurred whereby a neutral allele has changed in frequency by being linked to a mutation that swept through the population by selection. c. is a way of accounting for the proportion of variance in quantitative traits that is explained by particular linkage groups in a mapped genome. d. was championed by Thomas Henry Huxley in England and Asa Gray in America. e. was used extensively in the empirical work of Fisher, Wright and Haldane who are remembered mainly for their contributions to gathering data of this sort. 3. Genetic load a. should decrease if there is an increase in mutation rate. b. is the effect of a single locus. c. should increase in organisms with smaller genomes. d. is mainly the result of mutations that are lethal and not mutations that are deleterious, since the presence of a deleterious mutation does not necessarily mean the individual will die. e. is inevitable in every population because mutations are inevitable and elimination of inferior alleles implies a reduction in mean fitness. 4. After Mendel's laws were rediscovered, a. the old problem that blending inheritance doesn't allow selection to get anywhere in a large population was quickly laid to rest. b. the Mendelians and Biometricians cooperated to form the so-called "Neo-Darwinian Synthesis". c. Darwin revised The Origin of Species to take particulate inheritance into account. d. Fisher, Wright, and Haldane conferred with Darwin and arranged to have Mendel's paper presented at a meeting with a paper by Darwin read immediately thereafter. e. there were a couple of decades when evolutionary and genetical research developed but when there was not a realization that "many Mendelian genes of small effect" could account for gradual quantitative evolution. 5. Liebig's law of the minimum states a. all resources are more or less equally limiting. 1 b. conditions may be limiting, but resources will not be. c. biotic factors affect population size more than abiotic factors. d. populations tend to grow until limited by one factor or sometimes two. e. populations cannot go extinct because they would be saved by density dependence. 6. Under Haldane's model for selection against a recessive allele and for a dominant allele, write down the genotypic frequencies before and after selection given the chances of survival Haldane specified. Be sure that your frequencies are relativized. You may use the usual notation and shorthand of p, q, and W without going into how these are defined. (Note that the table does not strictly follow the presentation in the text–you have to understand what you're remembering). Relative chances of Relative Frequency Relative frequency Genotype survival before selection after selection AA 1 Aa 1 aa 1-s 7. Regarding niches, a. A realized niche is one that is the result of coevolution, whereas a fundamental niche is the result of ecological fitting. b. Warblers have fundamental niches, whereas badgers have realized niches. c. The realized niche is fixed–its existence and circumscription are real even in the absence of a species to fill it. d. Charles Elton believed that the niche is partitioned by competition among all the species that happen to exist in that particular community. e. G. E. Hutchinson treated the niche as a hypervolumn in hyperdimensional space where each axis of the space represents an environmental factor. 8. Microevolution a. can only occur by genetic drift, by definition. b. can only occur by natural selection, by definition. c. is descent with modification when applied to microorganisms such as bacteria and yeast. d. is defined as change in allele frequency over time. e. usually proceeds by the inheritance of acquired traits. 9. Which of the following is not an "ultimate" explanation but rather is a "proximate" explanation? a. The reason the vas deferentia loop way over the ureters rather than connecting directly to the urethra is because evolution proceeds by gradual quantitative modifications not by saltatory anatomical reorganizations. b. Polar bears have a pelt of long translucent hairs that are hollow and conduct light to their black skins where it is turned to heat, and short cream-colored hairs that are very good at retaining that heat. These features were selected for in the cold Arctic environment. c. In an experiment with 12 replicate lines of Escherichia coli, all evolved heightened glucose utilization efficiency (about 35% better than the ancestor) because selection favored parallel evolution in the glucose-limited environment provided by the researchers, but the 12 lines diverged in their latent abilities to use other sugars because of the randomness of mutations. d. If you had chickenpox as a child (or were vaccinated), you are very unlikely to get it again because exposure stimulated a specific lymphocyte in your system to proliferate into not only a large number of plasma cells that would have killed the chickenpox viruses but 2 also a large number of memory cells that are poised to attack any future chickenpox virus that is unlucky enough to be in your body. (The antigen-driven cloning of lymphocytes is called "clonal selection".) e. An experiment was done selecting for high bristle number in a population of flies. Bristle number went from 12 to 45 after 75 generations. Then selection was relaxed and bristle number went back down to 30 where it stabilized. The selection targeted on bristle number must have caused the evolution of deleterious alleles that were selected against through some unknown target after selection on bristle number was relaxed. 10. Given the same selection coefficient (s), when would evolution be the faster? a. Right after a new beneficial mutation arose as opposed to when it is near 50%. b. When the new allele that is selected for is recessive and the old allele that is selected against is dominant. c. When the allele that is being selected for is very near fixation (say q=95%). d. In an asexual haploid organism rather than a sexual diploid organism. e. a and b. 11. How has antibiotic resistance evolved since World War II? a. Many pathogenic bacteria have evolved resistance to one antibiotic after another because the use of antibiotics selects for resistance, and resistance spreads from strain to strain through transformation, transdunction, and conjugation. b. Because pathogenic bacteria had a long evolutionary history of flourishing in the presence of mold, they quickly evolved resistance to penicillin, but they have not evolved resistance to fluoroquinolones and other such modern antibiotics. c. Bacteria have such a short generation time, it takes them much longer to evolve than it takes humans and other large animals. d. Resistance to any one antibiotic has been selected for, but because bacteria don't have sex, bacterial lines don't mix their genes, and bacteria have not evolved resistance to multiple antibiotics. e. Bacteria have been around for much longer than other organisms. Some species are resistant to antibiotics and presumably have been for time out of mind. Others can be killed by antibiotics, and that hasn't changed in 65 years (and won't in hundreds of years). 12. Which of the following types of mutations is likely to be selected on, i.e., is not neutral or nearly neutral. a. a change in a nucleotide base that does not change the amino acid, i.e., is synonymous. b. a change in the nucleotide sequence in an intron. c. a change in a nucleotide that results in a bird having a song that humans notice as deviant. d. a deletion of several bases in a pseudogene. e. a change in a codon and the resulting amino acid that doesn't change charge or the active of the resulting enzyme. 13. Peter and Rosemary Grant and their students have studied Galapagos finches for many years. What do their results on selection on beak dimensions illustrate? a. The ecological causes of natural selection can be studied in the wild–during any one season in a small area selection might be measured as directional but averaged over many years it seems more stabilizing. b. It is essentially impossible to measure selection (at least in this system) because it is almost always minuscule–this is because organisms just don't vary to any measurable extent for characters that have been under selection.
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