L3 Pfiefer - Conservation Science 3

Question 1

What 2 patterns about island biogeography were proposed by MacArthur and Wilson

Answer 1

1. larger islands have more species than smaller islands

2. Near islands have more species than far islands (to mainland)

Question 2

What 2 processes about island biogeography were proposed by MacArthur and Wilson

Answer 2

1. the farther the island, the slower the rate of immigration
2. extinction rate in higher on smaller islands

Question 3

What are the 2 types of dispersal?

Answer 3

Directional dispersal - clearly targeted

random dispersal

Species pool on the mainland providing a source od immigrants for islands

Question 4

What are the 3 types of island?

Answer 4

1. Oceanic island
2. Land bridge islands (e.g. Britain)
3. Habitat islands

Question 5

What is a metapopulation?

Answer 5

a set of local populations occupying various habitat patches and connected to one another by the movement of individuals among them

generally considered to consist of several distinct population together with areas of suitable habitat which is currently unoccupied

Question 6

What are each Metapopulations like?

a) mainland - island
b) patchy

Answer 6

a) as long as the mainland population stays, the whole metapopulation wont go extinct
b) if you lose one patch, your species is like to become extinct.

Question 7

How do generalists and specialists respond to the edge of habitats?

Answer 7

Specialists don’t like the edge, therefore can be found in the centre of a patch. Habitats aren’t islands surrounded by inhospitable environments

Question 8

Define a keystone species

Answer 8

A species whose effect on the ecosystem is large and disproportionate to their abundance.

Question 9

What effects could make a keystone species a keystone species?

Answer 9

These could be species that are:

• ecosystem engineers
• species that control the dominance
• provide resources

Question 10

How are sea otters keystone species?

Answer 10

They’re considered a keystone species because of their critical importance to the health and stability of the near shore marine ecosystem.

They eat sea urchins and other invertebrates that graze on giant kelp.

Without sea otters, these grazing animals can destroy kelp forests and consequently the wide diversity of animals that depend upon kelp habitat for survival.

Question 11

What animal did Paine base his keystone species concept on?

Answer 11

Starfish (Piaster)

When removed from an environment, the number of species lowered, reducing the species diversity

Question 12

How are Beavers keystone species?

Answer 12

By cutting trees and using them to build dams, they alter the river flow, creating wetlands that might persist for centuries. This can change soil structure and nutrient content

Question 13

What is the insurance hypothesis?

Answer 13

This suggests that increasing biodiversity insures ecosystems against declines in their functioning caused by environmental fluctuations

Question 14

What is resilience?

Answer 14

Resilience: i.e. the capacity of a social-ecological system to absorb or withstand perturbations and other stressors, so that the system remains within the same regime, essentially maintaining its structure and functions

Question 15

What is the minimum viable population

Answer 15

the smallest size required for a population or species to have a predetermined probability of persistence for a given length of time

Question 16

what is the carrying capacity?

Answer 16

the maximum population size of the species that the environment can sustain given the available resources

Question 17

what would happen of your starting population was lower than the minimum viable population?

Answer 17

You’re in an extinction vortex