Invasive Species Case Study:
The Brown Tree Snake
The Hawaiian Archipelago is home to a particularly unique assemblage of endemic species. However, these species are currently being threatened by a variety of human impacts. To put the magnitude of the problem in perspective, the Hawaii Natural Heritage Program tracks 30 vertebrates, 102 invertebrates, and 515 plants that are considered to be "critically imperiled globally" (1-5 occurrences and/or fewer than 1,000 individuals remaining, or more abundant but facing extremely serious threats range-wide) or "imperiled globally" (6-20 occurrences and/or 1,000-3,000 individuals remaining, or more abundant but facing serious threats range-wide). For comparison, in New Jersey, which is approximately the size of Hawaii, the Natural Heritage Program tracks 3 vertebrates, 14 invertebrates, and 21 plants that are "critically imperiled globally" or "imperiled globally."
General Questions (all groups answer these):
1. Compare the terms ecosystem, community, species, and population as they relate to ecology.
2. What is the difference between exponential and logistic growth? What are some density-dependent factors that keep populations from growing exponentially indefinitely? What are some density-independent factors?
3. What is an ecological niche? What happens when two species have identical niches? How does the fundamental niche differ from the realized niche?
4. Explain an example of resource partitioning, and explain how natural selection can lead to character displacement.
5. Describe an example of each of the three types of symbiosis discussed in your text.
6. Explain how energy moves through the living components of an ecosystem (starting with primary productivity and including a discussion of food webs and ecological pyramids).
7. Explain how water, carbon, and nitrogen cycle through ecosystems, and give at least one example for each of how human activities can alter the cycle.
8. Seven different biomes are described in your textbook. If you were in charge of global ecosystem conservation but were told you had to focus all of your resources on preserving two of the seven types of biospheres, which would you choose, and why?
Questions specific to this case study:
5. What factors have produced the high biodiversity in general, and the large number of endemic species in particular, of the Hawaiian Islands?
6. Why are Hawaiian species particularly vulnerable to the effects of introduced species?
7. There is considerable fear that the Brown Tree Snake, a species not yet established
on the Hawaiian Islands, will be able to do so in the near future.
a. Where is the Brown Tree Snake native, and what is itŐs ecological niche in
b. What impact has this species had on another major island in the South
Pacific where it became established?
c. What are the potential impacts of the snake spreading through the
Hawaiian Islands? Which native species would be most impacted? Why?
d. What is being done to prevent the snake becoming established in Hawaai?
8. Describe the impacts of two other introduced species on the biodiversity of Hawaii.