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Flashcards in Competition and Population Growth Deck (35)
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Define a population?

A group of interbreeding individuals of the same species.


Define a resource?

Something that is consumed by an animal.


Define competition?

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


What can competition result in?

Reduction in survivorship, growth, reproduction


How might a population exhibit exponential growth?

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


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

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


What happens if...
R = 1
R < 1
R > 1

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


What effects will competition have?

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


What are effects on competition said to be?

Density dependant.


What is the Allee effect?

Positive density dependance.


When might you observe logistic growth?

Access to limited resources.


What 3 stages are shown in a logistic curve?

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


How do you calculate K?



What is exploitative competition?

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


What is interference competition?

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


What are Deterministic processes?

Intrinsic effects within the population and can be predicted.


What is Stochastic processes?

Extrinsic effects, are unpredictable.


What is Intraspecific competition?

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.


What is Interspecific competition?

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.


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

Competitive Exclusion


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

Resource partitioning.


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

Competitive release.


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

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.


What is the paradox of plankton?

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


Give possible answers to the paradox of plankton?

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.


Why are there less species in colder environments?

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


List some biotic factors present in the tropics?

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


What effect does land size have on biodiversity?

Larger area = more habitats, more resources.


What effect does island distance have on biodiversity?

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


Why are warm wet areas more productive?

Greater amount and range or resources = increased species richness.