Name ECOLOGY TEST #1 Fall, 2014 Answer the following questions in the spaces provided. The value of each question is given in parentheses. Devote more explanation to questions of higher point value. 1. H.A. Mooney and B. Bartholemew (Botannical Gazette, 1974) studied the phenology (timing) and physiology of two western species of Buckeye: California Buckeye (Aesculus californica), and a related species from Baja California, A. parryi. Unlike winter-deciduous buckeyes that occur in the eastern U.S., both of these western species are drought-deciduous. A. Parryi puts out leaves in December, and they senesce (wither) by February. A. californica typically puts out leaves in March, and they senesce by June or July. Figure 1 below illustrates the distribution of the two species and a provides a climate diagram illustrating mean monthly precipitation (dots) and temperature (x es) at several locations in or near their distribution range. Figure 3 illustrates the rate of carbon dioxide uptake in leaves of the two species at various temperatures. 1
a. Describe the direction (N, S, E or W) and temperature (warm or cold) of ocean currents off the coast of California and Baja California. Briefly describe how these currents affect the climate of California. (6) b. Based on the climate diagrams in Figure 1, during what months of the year would plants encounter drought stress in Eureka? (2) c. During which months of the year would plants encounter drought stress in Ensenada? (2) d. Why does A. parryi to lose its leaves earlier in the year than A. californica? (3) e. Would you expect individuals of A. californica to lose their leaves earlier in the season on slopes facing north or south? Why? (5) f. Explain why many locations like Baja California at 30 latitude north and south of the equator have a dry climate. (6) 2
g. Provide two reasons why carbon uptake of both species decreases at temperatures above approximately 20 C. (6) h. Would you expect A. californica to utilize C-3, C-4 or CAM photosynthesis? (2) i. Describe how and why climate would change as you proceeded east from San Luis Obispo to the Nevada border. (7) 3
2. Giant Sequoias (Sequoiadendron gigantea) only occur naturally in approximately 70 groves in the Sierra Nevada mountains of California. Answer the following regarding this species. a. Describe how extremes in soil conditions limit the distribution of sequoias. (6) b. Describe the fire ecology of sequoias that relate to their survival and reproduction. (6) c. How does the National Park Service manipulate the environment to promote sequoia populations? (3) 3. The figure below was introduced by ecologist Robert Whittaker to relate climate to major global biomes. Write in the approximate position of the following biomes: deserts; grasslands; temperate deciduous forests; tropical rain forests; tropical seasonal forests; taiga and tundra.(7) 4
4. The diagram below depicts the annual fluctuation in chlorophyll content in Mono Lake, which correlates to algal density in surface water. Use this information and your background knowledge to answer the following questions. a. Describe the food chain of Mono Lake. (3) b. What two times of year does deeper water circulate to the surface of a temperateclimate body of water such as Mono Lake? (4) c. Give TWO potential reasons why algae populations decline in June and July. (6) d. Why did the salinity of Mono Lake increased dramatically during the late 20 th Century? (3) e. Explain how the collapse of the Mono Lake ecosystem has the potential to dramatically impact the populations of many migratory bird species. (5) 5
5. Marine scientist P.F. Brodie compared the behavior, physical characteristics and energy budget of northern and southern hemisphere populations of fin whale (Baleanoptera physalus) (Ecology, 1975). Both populations reproduce in winter in subtropical waters, then migrate in summers to high latitudes to feed. The southern fin whale feeds in the very cold waters off Antarctica. The summer range of the northern fin whale is also in cold arctic water, but its habitat is not as cold the summer range of its southern relative. Fin whales must consume food intensively while in their summer feeding grounds in order to sustain themselves throughout the year, since food is scarce during the months spent in subtropical waters. The two populations differ in several physical and physiological respects, which are detailed in Table 1. a. Which population of fin whale has larger individuals? (2) b. Explain how the size differences may be an adaptation to different environments. (4) c. Describe how the natural selection process that could lead to size differences in these populations. (5) d. Explain why marine mammals are able to achieve a size greater than any terrestrial mammal. (4) e. Why should whales leave rich, polar feeding grounds to reproduce in food-poor tropical waters? (4) 6
6. The figure below depicts net carbon dioxide gain of leaves of the same species that grow in shade or sun. Full sunlight contributes approximately 2000 umol/m2/s of Photosynthetically Active Radiation (PAR).Use it to answer the following questions. a. Which leaf has a higher rate of photosynthesis in 50% of full sunlight? (2) b. What physiological process leads to a negative CO2 exchange at low light intensity? (2) c. Which leaf requires a higher leaf-nitrogen concentration? (2) d. What size differences would you expect to see between the leaves? Explain why it is advantageous to the plant to produce these differently-sized leaves. (5) 7