If the background rate of extinction were applied to birds, perhaps 2-4 birds sh

Question

If the background rate of extinction were applied to birds, perhaps 2-4 birds should have gone to extinct over the course of the last 800 years. What is the actual figure, and what does this mean for birds?

6) If the background rate of extinction were applied to birds, perhaps 2-4 birds should have gone to extinct over the course of the last 800 years. What is the actual figure, and what does this mean for birds? A) 6 Birds are going extinct at their background rate, as predicted by the model. B) 20 Birds have a higher than predicted rate of extinction, though it is not clear humans have had any effect. C) Between 200 and 2000. Birds, like many other species are in the midst of a major mass extinction event, with causes related to humans! D) More than 2000. Competition with mammals and insects, related to climate change, can explain most of these extinctions. E) Impossible to tell. 7) Which of the following statements about keystone predators is true? A. They usually competitively exclude other predators from the community B. They often maintain species diversity by preying upon the prey species that is the dominant competitor. C. They often increase the relative abundance of the most competitive prey species. D. They are not necessarily the most conspicuous, or abundant species in the community. E. Band D 8) The recovery of a volcanic island following complete sterilization by lava flows is an example of: A. Self-Annihilation B. Secondary Succession C. Primary Succession Degradation None of the above

Explanation / Answer

Answer 7. Both B and D

Keystone predators play an important role in maintaining ecosystem. If the Keystone predator is removed from the ecosystem, the Keystone prey explodes uncontrollably, driving out most other species, while the Keystone predators annihilates other species of the ecosystem.

A keystone species has a disproportionately large effect on its environment relative to its abundance. Their role is analogous to the role of a keystone in an arch.

Answer 8. Primary succession

The ecosystem is developing on an area which doesn’t support vegetation.

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