Reference no: EM133501309

Assignment: Environmental Science- Ecology

In this test, you will apply what you have learned in the unit. Please answer the questions below. Submit this to your teacher when you are done.

Question A. The gray squirrel is a rodent commonly found in the woodlands of Texas. The table shows information about four populations of this squirrel that were studied by researchers.

Habitat	Number of adults per acre	Ratio of young to adults
Pecan trees next to native desert	3	3:1
Pecan trees throughout a planted orchard	10	9:1
Pecan trees in housing developments	2	2:1
Pecan trees in agricultural areas	7	4:1

Question 1. Which habitats contain the lowest and highest densities of adult gray squirrels?

Question 2. Based on the ratios of young to adults given in the table, which population is likely to increase the fastest in the next few years? Explain your answer.

Question 3. How are the roles of pecan trees and gray squirrels related within an ecosystem? Hint: Think about how each species helps the other survive.

Question 4. Consider a population of 100 gray squirrels. The population is increasing exponentially, by a rate of 40% each year. If this rate continues, how many gray squirrels will there be in this population after two years?

Question B. Aphids are insects that feed on the sap of some flowering prairie plants, such as goldenrod. Ladybugs eat aphids, while ants protect aphids from predators and also "milk" them for sap.

Question 1. What is one abiotic factor that could limit an aphid population in a prairie? Explain.

Question 2. Describe two situations in which a healthy aphid population would start to experience positive population growth.

Question C. The Canada lynx is a predator of the snowshoe hare. The figure here shows changes to snowshoe hare and Canada lynx populations in Canada between 1845 and 1937.

Question 1. Describe how the carrying capacity of Canada lynx appears to be related to the carrying capacity of snowshoe hare.

Question 2. Coyotes are another predator of snowshoe hare. If a nearby population of coyotes suddenly leaves the area, how is this likely to affect the habitat's carrying capacity for lynx?

Question 3. How does the data set show the importance of studying any population over a long period of time to determine the habitat's carrying capacity?

Question D. Scientists are studying a mangrove community in coastal Florida. They find two species of mangrove trees: red mangroves and black mangroves. Each species provides food and habitat for a variety of animal species.

Question 1. What is one adaptation of a mangrove tree species that allows it to survive in its environment?

Question 2. Consider a lake ecosystem in northern Minnesota. What are two abiotic factors that would distinguish a mangrove community from this ecosystem?

Question 3. When scientists revisit the mangrove community 10 years later, they find that a third mangrove tree species, the white mangrove, has begun to grow there. How is this increase in biodiversity likely to affect the ecosystem's stability?

Question E. The saguaro is a common cactus in the deserts of the southwestern United States. The Gila woodpecker eats insects that damage saguaros. The bird pecks at the cactus to remove the insects. As it pecks, it removes damaged cactus tissue. It also makes a nesting cavity for itself. The nesting cavity does not negatively affect the saguaro. Any nesting cavity of a saguaro not being used by woodpeckers is available for use by lizards, rodents, and other birds.

Question 1. Why would the saguaro be considered a keystone species in its ecosystem?

Question 2. Name examples of predation, mutualism, and commensalism that involve the saguaro.

Question 3. What is one way a desert ecosystem would be affected if environmental changes were to cause a decrease in the saguaro population?

Question F. The diagram shows a food web in a mangrove swamp.

Question 1. How does energy stored in mangrove trees become available to the roseate spoonbill?

Question 2. How many producers and consumers are in this food web?

Question 3. Use the food web to draw a food chain that exists in this community, using arrows to show the direction of the transfer of energy. Approximately what percentage of the energy in the chain will be available to the highest trophic level?

Question G. Lava flows from a volcano on a tropical island. The lava covers an area containing grasses and shrubs. The burning edge of the lava starts a fire in an adjacent area of grasses and shrubs. This area burns completely but is not covered with lava.

Question 1. Which type of succession will take place in each area? Explain your answers.

Question 2. Which of the two areas is likely to take less time to get back to its original state before the lava flow? Why?

Question 3. What is one way an erupting volcano could have a global effect on ecosystems?

Question H. West Nile virus is a disease that is spread by mosquitoes, which lay their eggs in standing water. It was first identified in East Africa in 1937. It spread to the United States in 1999. This disease can cause swelling of the brain in humans. It can cause sickness and death in birds such as crows and jays. Predatory birds, such as hawks and owls, may catch West Nile from eating infected birds. The spread of West Nile is linked to unusually warm, wet conditions caused by global climate change.

Question 1. Explain how warmer and wetter conditions could increase the frequency of West Nile infections in both birds and humans.

Question 2. How could community stability and biodiversity be affected in ecosystems where West Nile virus is common?

Question 3. What is one action that humans could take to protect human and ecosystem health from the effects of West Nile virus?

Question I. The larvae of butterflies eat the leaves of flowering plants. Many of these larvae are eaten by birds before they can become adult butterflies. In one butterfly population, most larvae eat leaves continuously and ignore other organisms around the leaves. But a few newly hatched larvae stop moving when a shadow suddenly falls on the leaves. In a few years, most of the larvae in this population stop moving when they detect a sudden shadow.

Question 1. What is the adaptation in this butterfly population? Explain how you know it is an adaptation.

Question 2. Write a short paragraph describing the process that occurred in this butterfly population. Use the terms genetic variation, allele frequency, and natural selection in your answer.

Question J. The diagram here shows a food web for an open ocean ecosystem.

Question 1. The marlin population in this ecosystem disappears due to overfishing. How is this change most likely to affect the lantern fish and squid populations?

Question 2. A population of nonnative small fish is introduced into this ecosystem. This fish eats zooplankton and swims quickly to avoid predators. How is this nonnative population likely to affect the populations of lantern fish and ocean sunfish in this ecosystem?

Question 3. A different open ocean ecosystem has a food web containing only one species of large fish as prey for sharks. Is this ecosystem's number of shark species likely to be greater than, smaller than, or equal to that of the ecosystem with two species of large fish? Explain your answer.