Competition and Population Growth

Question 1

Define a population?

Answer 1

A group of interbreeding individuals of the same species.

Question 2

Define a resource?

Answer 2

Something that is consumed by an animal.

Question 3

Define competition?

Answer 3

An interaction between individuals brought about by a shared requirement for a resource in limited supply.

Question 4

What can competition result in?

Answer 4

Reduction in survivorship, growth, reproduction

Question 5

How might a population exhibit exponential growth?

Answer 5

Small starting population size, no predators, access to unlimited resources.

Question 6

How do you calculate r (intrinsic rate of increase)?

Answer 6

(Y2-Y1)/(X2-X1) taking the natural log (ln) of N.

Question 7

What happens if…
R = 1
R < 1
R > 1

Answer 7

R = 1 No change
R < 1 Exponential decrease
R > 1 Exponential increase

Question 8

What effects will competition have?

Answer 8

Fecundity (Birth rate), Size of individuals, size differences between individuals, allocation of resources within individuals, survivorship (Death rate)

Question 9

What are effects on competition said to be?

Answer 9

Density dependant.

Question 10

What is the Allee effect?

Answer 10

Positive density dependance.

Question 11

When might you observe logistic growth?

Answer 11

Access to limited resources.

Question 12

What 3 stages are shown in a logistic curve?

Answer 12

Initial exponential growth, decelerating growth rates, levelling off at the environmental carrying capacity (K)

Question 13

How do you calculate K?

Answer 13

(K-N)/K

Question 14

What is exploitative competition?

Answer 14

Destabilising, depletion, consumption, removal of resource without active interference, everyone suffers when shortages occur.

Question 15

What is interference competition?

Answer 15

Stabilising, resources shared unequally among individuals, winners and losers.

Question 16

What are Deterministic processes?

Answer 16

Intrinsic effects within the population and can be predicted.

Question 17

What is Stochastic processes?

Answer 17

Extrinsic effects, are unpredictable.

Question 18

What is Intraspecific competition?

Answer 18

is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals.; however, the most fit individual survives and is able to reproduce.

Question 19

What is Interspecific competition?

Answer 19

Interspecific competition is a form of competition between different species of the same ecological area. An example of interspecific competition is between lions and tigers that vie for similar prey.

Question 20

Define the term given when one species prevents all individuals of another species from utilising a resource?

Answer 20

Competitive Exclusion

Question 21

Define the term given when competing species appear to coexist as a result of differentiation of their realised niches?

Answer 21

Resource partitioning.

Question 22

Define the term given to the expansion of realised niche in absence of competing species?

Answer 22

Competitive release.

Question 23

What effect have ice ages had on the biodiversity of tropical forests?

Answer 23

Repeated fluctuations between wet and dry conditions allowed rapid evolution of forest organisms and have resulted in mass extinctions, thus reducing the biodiversity of forest organisms.

Question 24

What is the paradox of plankton?

Answer 24

How can so many species of plankton coexist in a simple habitat?

Question 25

Give possible answers to the paradox of plankton?

Answer 25

That there is little opportunity for niche diversification and as the environment is changing so frequently, conditions which favour one species do not persist for long enough to enable that species to outcompete all others and become dominant in the environment.

Question 26

Why are there less species in colder environments?

Answer 26

Requires physiological mechanisms and behaviour to tolerate cold/freezing such as dormancy, hibernation, migration…generally harder to develop.

Question 27

List some biotic factors present in the tropics?

Answer 27

Greater competition, more pressure from parasites and disease, prevents dominance of one species, coexistence at low numbers of individuals, increased niche specialisation.

Question 28

What effect does land size have on biodiversity?

Answer 28

Larger area = more habitats, more resources.

Question 29

What effect does island distance have on biodiversity?

Answer 29

Effects immigration/extinction, turnover of species. The further away an island is, the fewer species.

Question 30

Why are warm wet areas more productive?

Answer 30

Greater amount and range or resources = increased species richness.

Question 31

What is character displacement?

Answer 31

Alteration of morphology of a species as a result of the presence of interspecific competitors.

Question 32

What is apparent competition?

Answer 32

is an indirect, negative interaction between two species or species groups mediated by a third species other than their prey.

Question 33

What is the Allee effect?

Answer 33

is the positive relationship between the overall individual fitness and population density.

Question 34

What factors must a population have to exhibit exponential growth?

Answer 34

Lack predators, un-limited resources.

Question 35

What does R stand for?

Answer 35

Replacement Rate