FRWS 3810 Exam II. March 30, 2005

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1 FRWS 3810 Exam II. March 30, 2005 ID code: I. Match the appropriate term. There is one best answer (8 points). a. character displacement e. mutation load i. pseudosink b. n-dimensional hypervolume f. natal dispersal j. Fst c. k selection g. Wahlund effect k. chaos d. storage effect h. damped oscillations 1. The deleterious alleles in a population are collectively referred to as this e. 2. Subpopulations are all within Hardy-Weinberg equilibruim, but the overall population is not. g. 3. This refers to a species fundamental niche. b. 4. The pattern of dynamic behavior in the logistic model where population size first fluctuates, then stabilizes on an equilibrium. h 5. A measure of genetic structuring- the lower the value, the less genetic structuring among subpopulations. j 6. Juvenile animals leaving home and striking out on their own do this. f 7. Shifts in morphological traits due to competition a 8. A population whose growth rate is <1, but if density were reduced, growth rate would increase i. II. Fill in the blank (10 points). 1. An acorn woodpecker population is maintained by immigration of a few individuals per year. The immigrants are creating what is known as a rescue effect. 2. _scramble competition_ is a form of density dependence where all individuals share resources equally, and populations can fluctuate dramatically. 3. If individuals are harvested by hunters on top of natural mortality but no change in overall population size occurs despite the hunting, compensatory mortality has occurred. 4. Alleles are randomly lost from small populations as a result of this process. _genetic drift. 5. The size of a population needed to be equivalent to the number of individuals that lose genetic diversity at same rate as real population. effective population size. 6. The gradient of skunky-smelling flowers in Polemonium or increasing leaf hairiness with latitude in Spergula, are examples of a cline. 7. The realized niche is where you actually find a species when competitors are present.

2 8. Invasive plants often have a spreading pattern that depends on small outlier populations, or nascent foci. 9. interference competition is exemplified by the behavior of hermit crabs fighting over shells, as opposed to the exploitation competition exhibited by the species of bumblebees where the two species may never actually meet on the same flower. 10. The substitutive design for studying plant competition in mixtures holds the numbers of individuals constant, but changes the ratios of each species per trial. III. Write a few phrases or a sentence or two to answer 6 of the following 7 questions: (6 points each. If you answer all of them, I ll randomly choose 6 to grade!) 1. Why is carrying capacity a very useful theoretical tool that can be difficult to use in practice? Carrying capacity has at least two definitions. Also, it describes a steady state that is not achieved in nature, where resources fluctuate and populations are likely limited by different resources at different times. 2. When can an inferior competitor coexist with a superior competitor? An inferior competitor can coexist when there is a refuge from the superior competitor available, or aggregative behavior limits contact; when the inferior competitor is a better disperser; and when the superior competitor suffers disproportionately from mortality such as predation. 3. Draw a graph showing the behavior of a population under the logistic model. Label the axes. On the same graph, draw the rate of change over time (the second y axis).

3 4. What phenomena or characteristics must exist for a population to be regulated? Populations will persist through time, they will show bounded oscillations (boundedness), and will increase when small but decrease when large return tendency. 5. What are the components of evolution by natural selection? 1. Individuals are different from one another. 2. These differences are heritable. 3. They cause differing fitness among individuals. 4. Over time, gene frequencies within the population will change. 6. What are the general conclusions that can be drawn from the work of Brown and Davidson? Species need not be taxonomically related in order to compete; Competition does not always lead to exclusion of one competitor; Coexistence seems to often require some level of differential resource use; Either morphology or behavior can shift in populations experiencing interspecific competition. 7. List three major types of selection and give an example of each. Directional selection: one extreme phenotype has the best fitness, eg., widowbird tails; Stabilizing selection: the mean phenotype has the best fitness. Examples: human birth weight,flowering time in Senecio. Disruptional selection: The extreme phenotypes have the best fitness. Example: color patterning and behavior in garter snakes. IV. Short essay. Answer 3 of the 4 following questions (10 points each). 1. What are six possible mechanisms of coexistence in plants? Explain them briefly. Which assume equilibrium system dynamics, and which assume non-equilibrium system dynamics? 1. resource partitioning (niche separation). 2. spatial segregation clonal growth and seed dispersal as well as interspecific competition may promote this. 3. recruitment limitation- dispersal and competitive ability negatively correlated 4. pest pressure (Janzen-Connell hypothesis) prevents conspecifics from reaching high densities and competitively excluding other species 5. storage effect- good years for one species recruitment bad for another- allows seedlings to establish without interspecific competition 6. density-independent mortality the intermediate disturbance hypothesis. Mechanisms 1-4 assume equilibrium system dynamics, whereas 5-6 assume nonequilibrium system dynamics.

4 2. How do landscape ecology and metapopulation ecology differ? How are they the same? Draw a diagram to illustrate each in addition to your written answer. Landscape ecology: Patch quality varies across space and through time. Patch characteristics and dynamics are a function of their location relative to each other and the landscape around them. The movements of organisms and materials determine connectivity. Classic metapopulation: The patches are identical, and the surrounding area is ignored ( mean field assumption ). There are no patch dynamics- either they are occupied, or not. Patch size and inter-patch distance are ignored. 3. What factors influence how metapopulation structure affects genetic diversity? Do metapopulations enhance or limit genetic diversity, or both? Under what conditions? Metapopulations can enhance overall genetic diversity, but how much depends on the size of the subpopulations (ie, carrying capacities) and the amount of gene flow, which is determined by immigration and emigration rates. Generally a few large patches will maintain more diversity than a greater number of smaller patches of equal overall N. There should be multiple sources of colonists to new patches (or recently extinct ones), and all else being equal, the more patches the better. 3. What are four applications of genetics to conservation, ecology, and management? Give examples. Genetics can be used to infer taxonomic relationships to elucidate the units of conservation (such as the evolutionary significant units used in salmonid management). Genetics is also invaluable in captive breeding programs. Often, gene frequencies can help infer past events either on a geologic or recent time scale, such as the spread of trees in Britain following the last ice age and the occurrence of a bottleneck in cheetah populations. Finally, genetics helps infer rates of dispersal among populations. This use indicated that burrowing owl populations in North America are not isolated from each other. V. Answer the following questions based on the scenario given below (16 points total). A rare perennial plant, the Furbish s Lousewort, grows only along the banks of the Saint John s River in northern Maine. It relies on ice scour to create the early successional habitat it requires, and it does not seem to produce a seed bank. You have been hired by the Maine Department of Inland Fisheries and Wildlife to help manage this plant. An emerging issue is the introduction of

5 a new weed species that also relies on early successional riverbank habitat, and it is commonly spread by canoeists, unaware of the seeds that they carry in the mud on their gear. Conservationists and botanists worry that the new invader could negatively affect the lousewort. 1. Does this plant species fit a metapopulation model? Why or why not? (5 points). Botanical metapopulations are based on the absence of a seed bank (this distinguishes them from a relict population), and they are generally found in ephemeral and unpredictable habitats. Furbish s Lousewort does seem to form true metapopulations. 2. Before a very expensive eradication program is undertaken, it is decided to test whether the Furbish s lousewort might be competitively excluded by the new weed. Design a study to test this hypothesis. (3 points). In a greenhouse, a series of experiments should be performed. Ideally, a full additive experimental design should be undertaken, which incorporates both additive and substitutive designs that test for effects of density and also control for it. 3. Your boss wants to know some management interventions that might be taken if the lousewort begins to decline. One option is to actually create early successional habitat along riverbanks, and plant seedlings raised in greenhouses. (4 points, 4 points). a. What rules of thumb do you have for the placement of these patches relative to each other to maximize the likelihood that the outplanted seedlings will contribute to future population dynamics? Larger patches will be more likely to be colonized by future seedlings than small ones, and patches that are set close together are more likely to be colonized than those that are further away. b. What genetic concerns might exist regarding greenhouse rearing and transplanting into areas of native populations? Were the seeds originally collected from throughout the metapopulation? Is there any evidence of genetic structuring from among the subpopulations which would mean that seedlings should only be reintroduced into the source subpopulations they originally were collected from? If greenhouse populations are used to raise the seed, is proper genetic diversity being maintained with outcrossing?