Dispersal And Habitat Selection

Question 1

What is dispersal by diffusion?

Answer 1

Gradual recolonisation of suitable habitat after population crash due to hunting

Question 2

Give an example of dispersal by diffusion

Answer 2

The sea otter Enhydra lutris

Question 3

What is jump dispersal?

Answer 3

When individuals move across large distances, often crossing unsuitable habitat, and establish as a population in a new area.

Question 4

What is a human example of an accidental transplant experiment

Answer 4

Human activities resulting in the dispersal and introduction of exotic species to new areas.

Question 5

What are the four stages of pest species commencing?

Answer 5

Imported
Introduced
Established
Pest

Question 6

How can dispersal be a limiting factor? (S)

Answer 6

Invasive species- they are a consequence of removing barriers to dispersal

Question 7

Give an example of an invasive species as a result of dispersal as a limiting factor.

Answer 7

Salvinia molesta
- floating pond weed native to South America and introduced via human activity to Africa, India, australia

Question 8

What was the problem with the invasive species Salvina molesta? (Dispersal as a limiting factor)

Answer 8

-It reproduces vegetatively and grows rapidly, doubling its biomass in 3-4 days.
-Blocks waterways making them unusable for transport or drinking water
- wiped out fish populations

Question 9

What is the natural predator of Salvina molesta?

Answer 9

Cyrtobagous salvinae, feeds on the buds as adults and roots as larvae

Question 10

What problems occur from aquatic weeds?

Answer 10

• block access to and disrupts drinking water
  -interferes with drainage and irrigation , floods
  -changes ecology of natural aquatic systems

Question 11

What insect species were used to try to control the Salvinia molesta outbreak in Sri Lanka, India, Africa and Fiji?

Answer 11

A weevil, a moth and a grasshopper.

Question 12

What finally controlled the Salvina molesta outbreak?

Answer 12

A weevil ( C. Salvinae) brought the weed under control in one year.

Question 13

What was the benefit to cost ratio of the Salvinia molesta outbreak in Sri Lanka?

Answer 13

53:1 monetary terms
1673:1 labour terms

Question 14

What are the factors that influence species distribution?

Answer 14

-dispersal
-behaviour
-other species
-physical and chemical factora

Question 15

How can dispersal factors influence species distribution?

Answer 15

-area is inaccessible
- insufficient time for dispersal

Question 16

How can behaviour influence species distribution?

Answer 16

• habitat selection

Question 17

How can other species influence species distribution?

Answer 17

• predation
• competition
• parasitism
• disease

Question 18

What physical factors influence species distribution?

Answer 18

• temperature
  -light
  -soil structure
  -fire
  -moisture

Question 19

What chemical factors influence species distribution?

Answer 19

-water
-oxygen
-salinity
-pH nutrients

Question 20

What are the two main abiotic factors limiting species distribution?

Answer 20

• temperature
  -moisture

Question 21

What physical factors limit the distribution of coral reefs due to the narrow requirements of zooxanthellae?

Answer 21

• need temps of 18-30 degrees
• need solid substrate to grow on
• need access to light
• narrow range of salinity tolerance

Question 22

When identifying factors that limit distribution, what do transplant experiments provide?

Answer 22

Transplant experiments provide empirical evidence of species’ ability to survive outside of its current range.

Question 23

Give an example of the role of dispersal in limiting distribution.

Answer 23

The bull kelp in Kachemak Bay, Alaska

Question 24

What was the observation in the Bull kelp transplant experiment?

Answer 24

Surveys based on aerial photographs showed that Bull kelp forests only occurred in the outer basin and were absent from the turbid low salinity inner basin.

Question 25

Where was the Bull kelp present in the transplant experiment!

Answer 25

In the outer basin

Question 26

Where was the Bull kelp absent in the transplant experiment?

Answer 26

In the turbid low salinity inner basin

Question 27

What is the hypothesis of the bull kelp transplant experiment?

Answer 27

Decreased salinity and light intensity limits the distribution of Bull kelp in this system.

Question 28

What was the prediction in the Bull Kelp transplant experiment?

Answer 28

Bull kelp juveniles transplanted from the outer to the inner basin will not survive.

Question 29

What are the biotic factors that determine distribution of species?

Answer 29

Species interactions

Question 30

What are the abiotic factors that determine the distribution of species?

Answer 30

Environmental factors

Question 31

What are species distributions shaped by?

Answer 31

Adaptation and natural selection
Environmental and biotic change

Question 32

What are reasons a species are absent from a habitat that it could survive within?

Answer 32

-it can’t get there (dispersal)
- it does not recognise it as a suitable habitat (habitat selection)

Question 33

What factors prevent a species from being able to complete its life cycle outside its current range?

Answer 33

• interactions with other organisms eg: predation, disease, competition
• impacts of physical and chemical factors eg: temperature, light, moisture

Question 34

What is an Ideal Free Distribution?

Answer 34

When all individuals are free to move into any habitat without constraint

Question 35

What is an Ideal Despotic Distribution?

Answer 35

When all individuals are not free to move between habitats and the highest quality habitats are protected by territorial behaviour.