APES Free Response Questions - I will pick two of the Three questions below.
1. Southern sea otters, an endangered species, are typically found along the southern shores of California. They feed upon the abundant amount of clams, mussels, crabs, and sea urchins that are common in the kelp forests they inhabit. Although the fur traders hunted the species to near extinction in the early 1900’s, they have made a strong comeback in the last 50 years.
a. i. Determine, using the graph, in what year did the southern sea otter population in California reach 2,500?
ii. Based on the graph, how did the California sea otter population change from 1997 to the year 2000?
iii. According to the US Fish and Wildlife Service, the sea otter population will need to reach 8,400 individuals before it should be removed from the endangered species list. If the population grows by 50 individuals a year, how many years will it take to reach the USFW Service minimum population requirement?
b. Identify and describe TWO factors that may reduce the sea otter population.
c. Describe some reasons why organisms such as the southern sea otter, are often fund in clumps in the environment rather than random dispersion.
d. Sea Otters are often considered keystone species. Discuss how their disappearance in a community would impact the overall health of the ecosystem.
2. Scientists are alarmed at the drastic decline of amphibians in the last decade. In particular, frog populations seem to be declining at an alarming rate. The population decline seems to be linked to effects of exposure to harmful factors that occur at different points during their life cycle. Some of the environmental threats are natural while others are generated through human activities. Frogs are also sensitive to pesticides that make their way into our soil, air, and water.
a. Other that pesticide poisoning, identify and describe TWO possible reasons for the frogs decline in the ecosystem.
b. Describe some reasons why the frog may be particularly susceptible to pesticide poisoning in the environment.
c. Certain amphibians are considered indicator species for the ecosystem. Give an example of another indicator species and explain the environmental threat they may give warning to.
d. Identify TWO characteristics of species who are specialists that make them more vulnerable to environmental threats.
3. Humans have spent over 100 years and billions of dollars trying to drive various species of mosquito to extinction. Despite the inventions of pesticides, and the ensuing mass spraying of these chemicals, mosquitoes remain a human health threat. In contrast, we are experiencing the near extinction of of a variety of elephant species, despite our efforts to conserve them. The primary reason for this contradiction is that the mosquito is an r-selected species and the elephant is a K –selected species.
a. How do an r-selected species and K-selected species population growth rates differ? (Apply you knowledge of population growth curves)
b. What are the patterns of variation in population size for both creatures?
c. What are their frequencies of reproduction?
d. How many offspring do they both have?
e. How does this relate to their present risk of extinction?