"HOT-SPOTS"
"Hot-spots" are biologically rich areas with high diversity and a large percentage of endemic
species. For example, 20% of the world's plants are found on 0.5% of the earth's surface.
Biological hot-spots include the Western Amazon (Colombia, Ecuador, Peru), Madagascar, North
and eastern Borneo, Northeastern Australia, West Africa, and the Brazilian Atlantic forrest. All of
these areas have high diversity and many are threatened by human activities.
Global Biodiversity Hotspots
1. The Tropical Andes (Venezuela, Colombia, Ecuador, Peru, and Bolivia)
2. Madagascar
3. Brazil's Atlantic Forest Region
4. The Philippines
5. Meso-American forests
6. Wallacea (eastern Indonesia)
7. Western Sunda (in Indonesia, Malaysia, and Brunei)
8. South Africa's Cape floristic region
9. The Antilles
10. Brazil's Cerrado
11. The Darién and Chocó of Panama, Colombia, and Western Ecuador
12. Polynesia and Micronesian Island complex, including Hawaii
13. Southwestern Australia
14. The Eastern Mediterranean region
15. The Western Ghats of India and the island of Sri Lanka
16. The Guinean forests of West Africa
17. New Caledonia
18. Eastern Himalayas
19. Southeastern Australia and Tasmania
The WWF "Global 200"
In 1998, the World Wildlife Fund (WWF) devised a conservation strategy to replace the
biodiversity hot-spots first set forth by Myers 1977. The "Global 200," as the strategy is known,
expands the world's global conservation priorities to 233 eco-regions, comprising Earth's 19
terrestrial, freshwater, and marine major habitat types. By preserving these eco-regions, the
majority of Earth's biological diversity would be protected. For a complete listing of the Global
200,
A keystone species is a species that has a disproportionate effect on its
environment relative to its biomass. Such species affect many other organisms in an
ecosystem and help to determine the types and numbers of various other species in a
community.
Such an organism plays a role in its ecosystem that is analogous to the role of a keystone
in an arch. While the keystone is under the least pressure of any of the stones in an arch,
the arch still collapses without it. Similarly, an ecosystem may experience a dramatic
shift if a keystone species is removed, even though that species was a small part of the
ecosystem by measures of biomass or productivity. It has become a very popular concept
in conservation biology.
A keystone species is a species that plays a critical role in maintaining the structure of an
ecological community and whose impact on the community is greater than would be
expected based on its relative abundance or total biomass. The ecologist Dr. Robert T.
Paine coined the phrase to explain the relationship between Pisaster ochraceus, a species
of starfish, and Mytilus californianus, a species of mussel.
What are Keystone Species?
The keystone at the top of an arch holds all the stones in place. Without it, the arch
collapses. Healthy ecosystems needs keystones—like wolves and whitebark pines—to
function. Keystone species are the architects of biodiversity.
Many predators are keystone species. We focus on
far ranging species like wolves and bears in recognition of the complex, interactive, and
vital roles these species play in predator-prey dynamics.
Wolves
In the absence of wolves in Rocky Mountain and Yellowstone National Parks, elk
browsed willows in river and creek bottoms excessively. Now that wolves are back in
Yellowstone, riparian areas have come alive as long-suppressed cottonwoods and
willows are growing, providing vital habitat for songbirds. Beaver have also returned,
influencing water quality.
Wolves also play an important role in regulating other predators. With fewer coyotes,
antelope fawn survival has increased dramatically.
Grizzly bears
Grizzly bears play a highly complex role in ecosystems. In addition to predation on elk
and moose calves, grizzlies disperse seeds over large areas, and contribute to nutrient
cycling. Dubbed “ecosystem engineers” by some, the foraging activities of grizzly bears
may build or change the ecosystem. For example, coastal brown bears transfer salmon-
derived nitrogen into riparian ecosystems when they kill, move, eat, and leave some fish
in the forest.
