Island Biogeography

Question 1

What is island biogeography?

Answer 1

The study of the speices composition and species richness on islands

Question 2

How is an oceanic island created?

Answer 2

• by the uplift of magma from the seafloor created above hotspots,

Question 3

Describe how a chain of oceanic islands is formed

Answer 3

• continental drift causes one island formed to move away from the hotspot and then another is formed creating a chain of islands

Question 4

What is an archipelago?

Answer 4

a group/cluster of islands

Question 5

What does the species- area relationship describe?

Answer 5

The increase in species richness with increasing sampling area

Question 6

What types of islands have more species?

Answer 6

larger islands have more species

Question 7

what is genetic stochasticity?

Answer 7

• unpredictable changes in gene frequencies as a result of processes such as random genetic drift

Question 8

How is genetic stochasticity caused?

Answer 8

In small populations where inbreeding occurs limiting genetic information which could lead to extinction

Question 9

What is environmental stochasticity?

Answer 9

-unpredictable changes in the environment e.g. catastrophes or climate change

Question 10

Name the stochasticities which are problematic for small populations

Answer 10

• genetic (changes in gene frequencies)
• environmental (changes in environment)
• demographic (changes in birth rates)

Question 11

Name the mechanisms proposed to explain species-area relationship

Answer 11

• are per se
• habitat diversity
• evolutionary dynamics
• random placement

Question 12

What does it mean for an island to be more isolated?

Answer 12

• more isolated an island, greater amount of evolution and speciation

Question 13

Name the 2 ways in which the creation of new species can occur?

Answer 13

allopatric and sympatric

Question 14

Describe allopatric speciation

Answer 14

• geological barrier separates a population
• genetic drift
• random mutations
• one population can undergo new environmental factors
• natural selection
• populations become reproductively isolated

Question 15

Describe sympatric speciation

Answer 15

Population in new island, some become better adapted and become isolated, no geological barrier involved

Question 16

What is adaptive radiation?

Answer 16

The process in which organisms diversify rapidly from an ancestral species into a multitude of new forms by allopatric or sympatric speciation

Question 17

Why are islands hotspots of adaptive radiation?

Answer 17

due to the lack in numbers/variety of species and empty niche space

Question 18

Define depauperate

Answer 18

lacking in numbers or variety of species.

Question 19

Describe the effects of isolation on islands formed closest to the mainland?

Answer 19

• dispersal dominated system

- no speciation just constant immigration from mainland

Question 20

What are the isolation effects on islands furthest away from the mainland?

Answer 20

• species dominated system

- high rates of evolution where you can find high rates of extinction not found anywhere else

Question 21

Describe the Macarthur and Wilson theory

Answer 21

• proposes that the number of species on an island is in dynamic equilibrium between immigration and extinction

Question 22

What is the link between immigration rates and the isolation of an island?

Answer 22

The less isolated an island (closer to mainland) the higher immigration rates

Question 23

What is the link between the size of an island and extinction rates?

Answer 23

The larger the island, the lower the extinction rates

Question 24

What is the problem with the macarthur and Wilson theory on island biogeography?

Answer 24

• doesn’t consider the dynamics of islands

- islands carrying capacity thus must shift across time

Question 25

Define the carrying capacity of an island

Answer 25

The maximum number of organisms an island can contain

Question 26

How does an island’s carrying capacity change throughout time?

Answer 26

> immigration and extinction varies through time which means number of species on an island also varies

Question 27

Why is island conservation so important?

Answer 27

> recent rise in no. extinctions of islands, mainly human induced

Question 28

Name 5 causes of species extinctions

Answer 28

• hunting for food by humans
• museum and caged bird trade collecting
• introduced species
• disease, carried by vectors migrating to island
• habitats degradation and loss

Question 29

6 reasons why oceanic islands are susceptible to anthropogenic threats

Answer 29

• species poverty
• evolution in isolation
• ecological release of exotics
• early colonization by europenas
• small scale of island systems
• cross roads of international trade

Question 30

What is the matrix?

Answer 30

The land-use surroundings a patch habotat

Question 31

What was teh SLOSS?

Answer 31

A debate in conservation biology in 1970s-90s deciding if it was better to conserve single large areas or several small areas

Question 32

Why was it decided that it would be better to conserve several small areas like islands?

Answer 32

• Mcarthur and Wilson stated that smaller areas had higher extinction rates
• also if one small area has an extinction of population, it can recolonised from other populations in other areas
• greater habitat diversity