Lecture 23 Potential Exam Questions
1. What are the 6 threats to biodiversity and give an example of each?
- Over exploitation - over hunting of rhinos for their horns or the bushmeat hunting in tropical forests.
- Exotic Species - Asian carp in the Illinois River.
- Habitat Destruction - degradation and fragmentation.
- Climate Change - bobolink's habitat distribution will move northward into Canada.
- Pollution - NOx
- Domino Effect - The black-footed ferrets have suffered due to the decrease in prairie dogs.
Habitat Loss is the single largest threat to biodiversity. However, over exploitation is the largest concern with regards to the oceans biodiversity and the survival of animals in the bush meat trade.
2. What determines the success of an invasive species?
The aspects of the invader, the aspects of the receiving environment, and if the success rates appear to be high. It is likely if a species has been successful in one habitat, it will most likely be successful in other habitats. Also, not all invasive species are harmful when introduced into a new habitat.
3. What are the distinctions between "critically endangered", "endangered", and "vulnerable" species?
Critically endangered species are endangered species whose numbers are expected to decrease by at least 80% in the next 3 generations. There are approximately 3000+ critically endangered species listed currently.
Endangered species are species that at risk of extinction due to small population sizes or a lack of suitable habitat. Approximately 5000 species are classified as endangered.
Vulnerable species are those that are at high risk of extinction, but not in the near future. There are approximately 8000 species classified at vulnerable.
All of these classifications fall under the "threatened" category of the IUCN Red List.
4. What are good predictors of successful species invasion?
There are several predictors of successful species invasion, these include tolerance to a wide range of environments, similarity of the recipient environment to the source environment, size of introduction (the more introduced, the high the chance of persistence), a history of successful invasions elsewhere, and an ability to thrive in environments that have been altered by humans.
5. How does habitat fragmentation contribute to species extinction?
Habitat fragmentation causes the areas in which a species can persist to become smaller and more separated. This can isolate species from one another and reduce the genetic diversity of the patches (genetic drift is a potential problem). Additionally these patches may be too small to maintain populations for an extended period of time.
6. How do we estimate rates of species loss?
1. Estimate the probable number of species
2. Estimate the rate of habitat loss
3. Use the species-area relationship to estimate species loss (S = c A z)
Using this method, we can estimate that 25-50% of the worlds biodiversity will be extinct by 2100 (not including effects from climate change and invasive species).
7. What are the protected area categories for the IUCN?
Category I - Strict Protection - These areas are protected by science or wilderness protectors and are not accessible to the public
Category II - Ecosystem Conservation and Tourism - Generally large managed areas that are open to the public. They usually have qualities that are unique or outstanding. (National Parks)
Category III - Conservation of Natural Features - Ususally small areas protecting a specific outstanding natural feature. (Natural monuments)
Category IV - Conservation through Active Management - Areas that are protected and utilize wildlife species sustainably.
Category V - Landscape/Seascape Conservation and Recreation - Areas that are managed but also open for recreational uses to the public.
Category VI - Sustainable Use of Natural Ecosystems - Areas that are managed mainly for the sustainable use of the natural ecosystem.
8. What is a Gap Analysis and how is it used?
A Gap Analysis uses mapping of vegetation, animal, and land ownership to identify where there is a "gap" in the protected areas and the locations of the species that we are trying to protect. If a "gap" exists between where the species are located and where the protection area exists, then the species in that area are not being protected.
In order to perform a gap analysis you must first identify where the species you are interested in are located. Then you must determine the area currently under protection. When you compare these two, then you can determine where conservation areas need to be places.
9. What is necessary to have an effective nature reserve?
a. Must be large enough to maintain sufficient populations of all important species. -This means that the area should be large enough to support viable populations of all species that are vital to the health of the ecosystem including keystone species, threatened species, etc…
b. Should protect several kinds of species. - This means that it should support metapopulations and these sub-populations should be distinct, but with some inter-connecting via corridors and stepping stones.
c. Should minimize "edges" and fragmentation effects. - Rounder shapes create less edge and more internal space. Breaking up the reserve through roads, settlements, etc… should be avoided.
d. Should consciously include the matrix of unprotected land in which it is embedded. - Forming partnerships with those public and private landowners surrounding a reserve is important to foster communication and ease dispute resolution.
10. Describe the difference between background, mass, and anthropogenic extinctions.
Background extinction is the "normal" extinction rate. It is the rate of extinction in earth's historical record. This involves evolution from one species to a new species or simply the disappearance of a species.
Mass extinction occurs episodically and involves many species going extinct withing a short period of geological time. There have been five major mass extinctions.
Anthropogenic extinction by human causes. These can include over-exploitation, introduction of exotic species, habitat degredation, climate change, pollution, and domino effects.
11. Of the Sextet of Threats, which are the most important? Although it isn't considered one of the biggest threats, what is an important threat for oceans and bushmeat animals?
Habitat loss is the single largest threat to biodiversity, followed by the introduction of invasive species. However, overharvesting of fish is the single largest threat to biodiversity in oceans. Overharvesting of bushmeat for commerce and subsistence is also the greatest threat to vertebrates in tropical forests of central and west Africa.
12. How does human intervention exacerbate species extinction?
i. Habitat Loss and fragmentation – In many cases, the extent of biodiversity is directly related to habitatable area in a given ecosystem. Intrusion by humans into these areas reduces the ability of the ecosystem to support larger populations of species. Also, fragmentation limits individual dispersal, making a population increasingly exposed to climate changes, often resulting in extinctions of local populations.
ii. Small population size – Natural variations in population size can make a species more susceptible to extinction at a given point in time, known as stochastic extinction. Habitat fragmentation can accelerate this phenomenon, especially with larger predators who typically have low population densisites.
iii. Overexploitation – Hunting, fishing, deforestation, agriculture and other activities put severe stress on native populations that didn’t evolve to contest against the harvesting humans employ to draw natural resources. Certain species’ lack of defenses and failure of hunters to recognize the dangers of exploitation have led to rapid extinctions.
iv. Species introductions – New predators, competitors or pathogens introduced by humans can have dramatic effects on an ecosystem. Native species may not have the evolutionary defenses to cope to aggressive new entrants nor the time to adapt.
v. Emerging diseases – Animals and plants get sick too and human behavior can sometimes carry infectious diseases and bacteria to new exotic locals where current inhabitants have no natural defenses.
13. How can we measure the value of biodiversity?
Social, economic, moral and ecological issues all come into play when species biodiversity is challenged. Some argue that humankind has a moral responsibility to respect plant and animal life. Others measure biodiversity in terms of the economic value that can be assigned to the many components that comprise an ecosystem. Of course, this perspective stratifies the natural world and assigns greater value to some animal and plant life than others. Biodiversity can also be a value indicator of environmental vitality and ecosystem functionality. Certain species, such as predators or other “keystone” species, have intrinsic value for stabilizing ecosystem sustainability (such as those we’ve explored in our stella labs).
14. Given the varying reasons for species extinction, how can we as humans best protect biodiversity? And what are some of the possible parameters we can use to measure effectiveness?
Biodiversity can be best protected by protecting habitat in areas where there is already high biodiversity, such as in the tropics. Since habitat loss is the biggest factor in loss of species, habitat destruction must be avoided, and where possible, restored. Protected areas must be big enough to support substantial populations. That said, it's not just a matter of creating protected areas. The matrix around such areas, as well as human-dominated landscapes, must also be managed well to avoid isolating populations.
Biodiversity Interesting questions:
1. Choose one of the six threats to biodiversity presented in lecture and argue why it is the most important. What are the implications of this threat? What natural ecosystems are impacted by it? What human institutions are impacted by the threat? What policies would you present or support to address this threat?
2. Describe how the relationship between habitat area and number of species relates to forecasting of future extinctions? Is this true in all cases? Why do different sized islands demonstrate this effect so effectively?
3. Define/ in biodiversity terms:
a. Endemism
b. Hot spots
c. Matrix
d. Domino effect
e. Size matters
f. Nuisance is in the eye of the beholder
4. Give a quick “elevator speech” of why we are in the sixth extinction and what it means for the future of humanity.
