Ecology

Question 1

What is one good hypothesis that explains species diversity?

Answer 1

Keystone Predator Model. A predator causes high levels of mortality in the more competitive species, increasing space for other species.

Question 2

Prediction of Keystone Predator Model

Answer 2

Removal of a top predator will reduce the overall number of species present.

Question 3

Examples of keystone species:

Answer 3

Otters, Sea Stars, bears, salmon, jaguars.

Question 4

Idea of “Disturbance”

Answer 4

There is maximum diversity with some disturbance going on. Predators act as disturbance, so do waves on beaches…

Question 5

How do we explain island bio-geography?

Answer 5

Equilibrium Theory: predicts the number of species as a sort of equilibrium between species immigrating and going extinct.

Question 6

Why is the rate of immigration high when there are few species?

Answer 6

Because colonists don’t have to fear predators. No competition.

Question 7

Why is the rate of extinction high when there are many species?

Answer 7

Lots of competition, there are lots of species that could be going extinct at any time.

Question 8

How does island area and isolation affect the equilibrium?

Answer 8

Far from mainland = reduced immigration

Larger Island = reduced extinction.

Question 9

How well does the Equilibrium Theory fit with the data?

Answer 9

Perfectly. Both observationally (catalina islands), and experimentally (mangrove forest).

Question 10

Extensions of the theory:

Answer 10

Rescue effect = close things can save each other, reducing extinction. Target effect = bigger islands will catch more colonists.