R-Selected Traits in Action

1. Are most invasive (exotic) species K-selected or r-selected species? Explain your choice and why that makes sense in terms of their ecological success. Invasive species are often said to be r-selected. However, invaders must sometimes compete with related resident species. In this case, invaders should present combinations of life history traits that give them higher competitive ability than residents, even at the expense of lower colonization ability. 2. Briefly define a community and an ecosystem and describe how the two are interrelated. A community is a variety of species living within one area. A community is made up of a variety of populations. Populations are only one type of species. Whereas, an ecosystem contains both biotic and abiotic factors. An ecosystem is determined by both the biotic (living) and abiotic (nonliving) factors. An ecosystem could be something as small as a pond to something larger such as a forest. Abiotic factors include amounts of sunlight, soil, and climate. A very large ecosystem could be a biome such as a desert, chaparral, tundra, or savannah. 3. Which of the following levels of organization are in order, from simplest to most complex. a. population, organism, community, ecosystem b. community, ecosystem, population, organism c. organism, community, population, ecosystem d. population, ecosystem, organism, community e. organism, population, community, ecosystem 4. Mosses growing on bare rock will eventually help to create soil. These mosses are involved in ___ succession. a. primary b. secondary c. tertiary 5. If a farmer sprays a pesticide onto a field and kills half of the insect pests, he has caused a reduction in________. a. field capacity b. carrying capacity c. population size d. More than one of the above 6. What type of survivorship curve would you expect for a plant species in which only a few seeds are produced and most of these survive to produce adult plants? a. type I b. type II c. type III 7. An ecological niche is an organism's_______ in an ecosystem. a. location b. habitat c. resources d. function 8. No matter how rapidly populations grow, they eventually reach a limit and begin to stabilize. This is called the _capacity__. 9. Unicellular algae live in the tissues of coral animals. The algae provide food for the coral, while the coral provides a stable home for the algae. This is an example of a. Parasitism b. Commensalism c. Mutualism 10. The vast majority of energy taken into an ecosystem is____________. a. converted into biomass by plants. b. utilized by secondary consumers. c. lost as heat. d. used by the primary consumers. e. concentrated in the decomposers. 11. A farmer is using an insecticide to treat his crops. While most insects do not survive their first exposure to the insecticide some have a gene that enables them to survive. When these survivors reproduce they will likely pass along this resistance to their offspring. This results in an increase in numbers of the insects over time. Which of the following processes applies to this survival? a. cloning b. mutation c. natural selection d. genetic engineering 12. What is the ecological relationship between insects and crops? a. mutualism b. competition c. predation 13. Sea anemones growing on the backs of crabs without damaging the crabs are an example of a. Parasitism b. Commensalism c. Mutualism 14. Which of these is a population density-independent regulating factor? a. Competition b. Predation c. Size of population d. Weather e. Resource availability 15. Producers are_________. a. Autotrophs b. Herbivores c. Omnivores d. Carnivores 16. If biological magnification occurs, the ___ will have the highest levels of toxins in their systems. a. producers b. herbivores c. primary carnivores d. top carnivores 17. Given the amount of sunlight that hits the plants on our planet, and the ability of plants for rapid growth and reproduction, how come we aren’t all hip deep in dead plants? The process of decomposition takes care of it for us, although not as quickly as some would prefer. When pants die, they decompose, mix with the surrounding soil, and provide nutrients for other plants and animals. Decomposition is the method by which once living matter is broken down after the organism in question dies. Decomposition breaks down the dead organism into more basic components that the cause the organism to disintegrate and assimilate into the surrounding environment. This process is essential for there to be adequate space in our biosphere for new living organisms to function and move about. Various species of fungi and bacteria are the primary machines in the process of decomposition. Therefore, due to the process of decomposition, we do not face the dilemma of having to warehouse dead organisms over the millennium – as they are all effectively recycled into the soil and atmosphere of the Earth through the process of decomposition. The following Grading Rubric will be used to score your homework: Questions Expectation Points 1 Demonstrates an understanding of the characteristics of r- and K-selected species. 2 Correctly defines the two terms and explains how the two are related. 0-3 Demonstrates an understanding of ecological concepts. 0-14 3-16 17 TOTAL Applies the knowledge of trophic levels in a real-world situation. {{{{{{{{{{ 0-3 0-3 23 pts