Lecture 10

Question 1

What is an island?

Answer 1

Some sort of isolated habitat that is surrounded by a different habitat, so the organisms have to get through an inhabitable place to get to the island.

Question 2

The study of succession and what is closely linked?

Answer 2

The presence of animals can be directly correlated with seral stage but animal diversity is independent of plant succession
Continent wide succession has been occurring in North Eastern North America for the past two centuries
The study of succession and conservation are closely linked

Question 3

What is Island Biogeography?

Answer 3

Island biogeography is the study of colonization and survival in island communities. The theory of island biogeography was developed to explain patterns of species richness on islands.
Early naturalists observed that larger islands have more species than smaller islands.

Question 4

What are examples of islands?

Answer 4

A piece of land surrounded by water.
An oasis in the desert.
A woodlot in the center of a farm field.
A park in a city.
A wetland surrounded by farmland (e.g., a slough).

Question 5

What does Island Biogeography combine?

Answer 5

Connectivity (how the island is connected to the source population) and patch size (how big is the island).

Question 6

What is the goal of Island Biography?

Answer 6

To establish the equilibrium number of species on any given island (S value). Stability is achieved when the immigration of new colonizing species equals the extinction of previously established species.

Question 7

What is the number of species present a combination of?

Answer 7

How quickly animals go extinct versus how long it takes for new species to arrive.

Question 8

Why would immigration rate decline? (2)

Answer 8

1) When all mainland species are found on the island, the immigration rate is zero (no new species available)
2) Successful establishment of a new species on an island is based on whether their niche has been filled yet, if their needs are the same as an established species they either successfully compete or die.

Question 9

What happens to immigration rates as the number of species goes up?

Answer 9

The immigration rate of new species declines and extinction rate increases.

Question 10

Why does the extinction rate increase as the number of species occupying the island increases?

Answer 10

Later immigrants may be unable to establish populations because earlier immigrants already occupy available habitats and resources.
As the number of species increases, competition will likely increase, causing an increase in the extinction rate.

Question 11

What happens when the number of species living on the island exceeds S?

Answer 11

The extinction rate is greater than the immigration rate and the species richness will decline. Extinction will go down, and immigration will increase.

Question 12

What happens when the number of species living on the island is lower than S?

Answer 12

The immigration rate is greater than the extinction rate and species richness will increase. Immigration will go down, extinction will increase.

Question 13

How is the equilibrium affected by the size of the island and the distance from the mainland?

Answer 13

The greater the distance, the less likely species will be able to successfully disperse.
If the islands are the same size, S will be lower for the island father from the mainland.
If the islands are the same distance from the mainland, S will be greater for the larger land.

Question 14

Why do larger islands have a greater S?

Answer 14

On larger islands, extinction rates are lower. Larger islands generally have more habitats and resources.

Question 15

What area is great for study Island Biogeography?

Answer 15

The Caribbean.

Question 16

Describe an example of Island Biogeography with bird species.

Answer 16

Numbers of lowland forest bird species in Polynesia decreased with the distance from New Guinea (the source of colonists for these islands). Studies of the Lesser Antilles found a significant relationship between island area and species richness.
Analysis indicated that island size, climate (precipitation and temperature) are important in explaining bird richness as is distance from the mainland.

Question 17

What is adaptive radiation?

Answer 17

How diversity can change in an island in the absent of immigration and extinction events. The process whereby a single ancestral species evolves into a wide array of descendant.

Question 18

What is a good example of adaptive radiation?

Answer 18

Cichlid fish in African Rift Valley Lakes.

Question 19

How does size of a reserve affect species richness?

Answer 19

Larger reserves are better than smaller ones. Larger ones will hold more species and experience fewer extinctions.

Question 20

How does fragmentation of reserves affect species richness?

Answer 20

Given equal area, habitats should not be fragmented. Clumps are better than fragments, and if it must be fragmented-the closer the fragments, the better.

Question 21

What is a Metapopulation?

Answer 21

The examination of species richness of a single habitat patch as a function of colonization and extinction (one species in a certain area).

Question 22

What is Metapopulation theory?

Answer 22

It examines the colonization and local extinction of local populations of a species on an array of patches in a broader landscape. For a particular species, the landscape is patches of potential habitats that vary in size, quality, degree of isolation from one another.
Each patch can potentially support a distinct, partially isolated subpopulation. This local population has its own population dynamics and is connected to other patches by varying degrees through dispersal of individuals.

Question 23

What does Metapopulation dynamics involve?

Answer 23

Two sets of process operating at two distinct spatial scales: single patch (individuals move and interact with each other during routine activities) and landscape (local populations interact through dispersal and colonization).

Question 24

What is meant by metapopulation persistence?

Answer 24

All local populations can potentially go extinct - metapopulation persistence results in recolonization.

Question 25

What is colonization?

Answer 25

The movement of individuals from occupied patches to unoccupied patches. Individuals from an existing population form a new local population.

Question 26

Dispersing individuals and metapopulations.

Answer 26

Dispersing individuals may have a significant chance of failing to locate another suitable patch to colonize.
This dispersal of individuals between local populations is key to metapopulation dynamics.

Question 27

What are metacommunities?

Answer 27

A set of local communities inhabiting discrete patches that are linked by dispersal. More than one species.

Question 28

What are interactions among communities influenced by?

Answer 28

The size of the habitat patches, shape of the habitat patches, spatial arrangement of the habitat patches, and matrix in which the habitat patches are embedded.

Question 29

What does the species composition of patches determine?

Answer 29

The nature of species interactions influencing the ability of a new species to colonize a patch and the ability of current species to persist in a patch.

Question 30

Describe a change in mosaic.

Answer 30

The mosaic of communities that defines a landscape is constantly changing. Disturbances alter the biological and physical structures of these communities. Successional changes occur within these communities. Different patches are in different phases of successional development.

Question 31

What is the Shifting-mosaic steady state?

Answer 31

A theory that is used to describe the process of succession and predict the state of a community.
In other words, while the characteristics of individual forest patches change through time, the collective properties of the patches remain relatively constant – in a steady state because statistically speaking a forest should have the same amount of disturbance/succession through time.