Lecture Seven

Question 1

What is Competition?

Answer 1

Interaction among two or more individuals that attempt to use the same resource, such as food, water, sunlight, or living space.

Question 2

What is Intraspecific Competition?

Answer 2

Competitive interactions between two individuals of the same species.

Question 3

What is Interspecific Competition?

Answer 3

Competitive interactions between two different species.

Question 4

What is Exploitation Competition?

Answer 4

Can be intra- and interspecific, organisms are competing for the same resource but not directly interacting.

Question 5

What is Interference Competition?

Answer 5

Can be intra- and interspecific, there is direct competitive interactions.

Question 6

What is Consumption Competition?

Answer 6

Individuals of one species inhibit individuals of another by consuming a shared resource (Interspecific, Exploitative).

Question 7

What is Pre-emption Competition?

Answer 7

Individuals of one species prevent occupation of an area by individuals of another species by getting there first (Passive, Interspecific, Exploitative).

Question 8

What is Overgrowth Competition?

Answer 8

Individuals of one species grow over individuals of another species, inhibiting access to a resource (tall plants over short plants, Interspecific, Exploitative).

Question 9

What is Chemical Interaction Competition?

Answer 9

Individuals of one species release growth inhibitors or toxins that inhibit or kill other species (Interspecific, Interference)

Question 10

What are examples of Chemical Interaction Competition?

Answer 10

Allelopathy in plants – secretion of chemicals that inhibit germination of other species.
Yeast and sugar produce a waste product (alcohol) that kills bacteria to keep sugar for itself.

Question 11

What is Territorial Competition?

Answer 11

The behaviour of one species excludes another species from a specific location that is defended as a territory (territorial, actual fighting. Interspecific, Interference).

Question 12

What is Encounter Competition?

Answer 12

A non-territorial encounter between individuals of different species that affects one or more species involved, such as scavengers fighting over animal carcasses. (Interspecific, interference).

Question 13

True or False: Interspecific competition can have strong influence over the structure of communities (give an example).

Answer 13

True, purple loosestrife is an invasive plant from Europe that is out competing native wetland vegetation.

Question 14

What is the Competitive Exclusion Principle and does is apply to reality?

Answer 14

When two species compete directly for the same limiting resources; the more efficient species will eliminate the other. In reality complete competitive exclusion is uncommon as no two species have exactly the same requirements and so total elimination won’t occur. Coexistence.

Question 15

Can the Competitive Exclusion Principle happen?

Answer 15

In labs, such as with Paramecium species competing (P. Aurelia and P. caudatum, the latter being driven to extinction).

Question 16

Give a real-life example of the Competitive Exclusion Principle.

Answer 16

A field experiment with barnacles that attach to intertidal rocks on the Atlantic Coast. Chthamalus occupies the high tide area which remains out of water longer
Balanus is found on the lower rocks; it is less tolerant to drying
If Balanus is removed from lower rocks, Chthamalus will also colonize the lower rock. However, if both species are permitted to colonize the rock Balanus displaces Chthamalus on the lower rock.
Therefore, the upper limit of Balanus’ distribution is set by the availability of water, whereas the lower limit of Chthamalus distribution is set by competition.

Question 17

What is a Niche?

Answer 17

The sum total of the biotic and abiotic resources an organism uses. For example, the temperature range for a population, the time of day it feeds, and the type of food it consumes are all part of a populations niche.

Question 18

What happens when the niche of two or more species are very similar?

Answer 18

Then one or more species may be driven out of the habitat by competitive exclusion.

Question 19

What is Resource Partitioning?

Answer 19

The reduction in competition among coexisting species. Over time natural selection favours individuals of each species that avoid, or at least, reduce competition for limited environmental resources.

Question 20

What are the Warblers in Spruce Trees and example of?

Answer 20

Resource Partitioning, the Warblers in this example all feed for insects on the same species of tree. To avoid competition they have divided up the feeding habitat within the tree; thus feeding in differing micro-habitats and avoiding competition.

Question 21

What is Competitive Release?

Answer 21

Resulting when competition between species stops for whatever reason, it is the expansion of a species niche when the competitor is no longer present. This may happen when a species invades a habitat that is free of potential competitors.

Question 22

Define Symbiotic Relationship.

Answer 22

An interaction between two or more species in which one species lives in close association with another species.

Question 23

What are the three main types of symbiosis?

Answer 23

Parasitism, commensalism, and mutualism.

Question 24

What is Parasitism?

Answer 24

A kind of predator-prey relationship in which one organism, the parasite, derives its food at the expense of its symbiotic associate, the host. Parasites increase their fitness by using the host for food, habitat, and a means of dispersal, they do not usually kill the host. Pin worms are an example, as well as ticks.

Question 25

What is Parasatoidism?

Answer 25

When the parasite kills the host.

Question 26

What happens to the parasite when the host organism dies?

Answer 26

Parasites must leave one host and relocate to another before host death but often cannot do this at will. To successfully migrate a host must adapt its own life history with hosts feeding, social, and mating behaviours.

Question 27

What Parasitism example happened with rabbits?

Answer 27

Introduced rabbits overran the Australian countryside in 1940s, myxoma virus, a parasite of rabbits, was introduced to control the rabbits in 1950 and the rabbit population was devastated. Over the years, the virus became less effective as rabbits become resistant to the virus.
In addition, the deadliest strains of the virus disappeared with their hosts; natural selection favoured strains that infect a host without killing it.

Question 28

How does the host adapt in parasitism relationships?

Answer 28

To minimize the impact of the parasites through immune responses (common in micro-parasitic infection and less common in macro-parasitic infection) and behavioural defences (to help avoid infection).

Question 29

What is Commensalism?

Answer 29

A type of symbiosis in which one organism benefits and the other one is neither harmed nor helped.

Question 30

Is absolute Commensalism common?

Answer 30

No, because it is unlikely that one partner remains completely unaffected.

Question 31

What is an example of Commensalism?

Answer 31

Birds eating insects that have been flushed out of the grass by grazing cattle.
The birds benefit by feeding on the insects kicked up by the cattle; unlikely the cattle gets any benefit from the relationship.

Question 32

What is Mutualism?

Answer 32

A positive interaction between two species that can be characterized by a number of benefits such as provision of essential resources (food, shelter), protection from predators, herbivores, parasites, reduction of competition with a third species, enhanced reproduction provision of essential resources (food, shelter), protection from predators, herbivores, parasites, reduction of competition with a third species, enhanced reproduction.

Question 33

What are Obligate Mutualists?

Answer 33

Organisms that cannot survive or reproduce without the interaction.
Some associations are so permanent and obligatory that the distinction between the two organisms blurs.

Question 34

What are Facultative Mutualists?

Answer 34

Organisms that can survive and reproduce without the interaction.

Question 35

What is the Mutualistic relationship between Acacia Trees and Ants?

Answer 35

Tree provides ants with: shelter, sugar and protein secretions.
Ants provide tree with: protection against herbivores, and reduce competition from surrounding plants for sunlight (ants clip neighbouring plants).
If ants are removed from the acacia tree the acacia tree dies.

Question 36

What is the common mutualistic relationship between bacteria and plants?

Answer 36

In this relationship the bacteria fix nitrogen for the plant (make it biologically available). The plant provides housing (often in nodules) that provide the bacteria with protection and nutrients.

Question 37

What is the mycorrhizae mutualistic relationship?

Answer 37

A mutualistic relationship between plants and fungi (at least 80% of vascular plants have fungi associated with their roots. Fungi provide: minerals, water and protection against pathogens (other fungi) and nematodes. Plant provides: carbohydrates and vitamins.