Competition For Resources (C5) Flashcards
IFD =…?
Competition through the exploitation of a common resource.
IDD = …?
Resource defense competition.
Flow of concepts throughout Behavioural Ecology? (3)
Individual + Food
|
Individual + Food + Predation
|
Individual + Food + Intraspecific competition
How does the presence of conspecifics influence the individual’s behaviour?
How does competition influence population dynamics?
• Influences reproductive success & survivability.
• Provide more info, pls.
How does competition influence the distribution of the individuals?
Increased competition causes the outcompeted individuals to move to poor areas even though they have less resources.
Essential resources that lead to intraspecific competition? (3)
• Food.
• Territory.
• Mates.
Competition for resources leads to changes in? (3)
• Behaviour.
• Morphology.
• Physiology.
All changes in behaviour, morphology & physiology drive/lead to…?
Evolution.
IFD assumptions besides “ideal” & “free”? (3)
• No territoriality.
• No fighting.
• Prey items consumed by one individual become unavailable to others.
Optimal behaviour/ IFD equation?
U = Q/n
IFD equation symbols? (3)
U = value of the environment.
Q = quality of the environment.
n = number of individuals.
U = Q/n?
Population is partitioned between the environment in proportion to the environment’s relative productivity.
Why the “Ideal” in IFD?
Assumes that individuals are ideal as they have complete information about the availability & distribution of resources.
Why the “Free” in IFD?
Assumes that individuals are free to move from one area to another.
Explain IFD graph? (2)
● Because you have an equal reward in both habitats, you are free to go into any habitat, rich or poor (individuals who go into the poor habitat still gets the exact amount of resources).
● As you have more individuals coming into an area, more individuals will share resources, resulting in a less reward per individual.
IFD prediction?
Competitors adjust their distribution so that all individuals have the same rate of resource acquisition (i.e., high quality areas will have the most individuals & low quality areas will have the fewest individuals).
IDD attribute?
• The stronger competitors secure the better habitat.
Why the “Ideal” in IFD?
Assumes that individuals have complete information about resource availability.
IFD axes? (2)
• x-axis = number of competitors.
• y-axis = reward per individual.
Explain IDD graph? (3)
● Rich environment is over poor habitat.
● a = rich habitat becomes full & newcomers are forced to occupy poor habitats.
● When b is reached, further competitors are excluded from resources.
IDD axes? (2)
• x-axis = number of competitors (a & b).
• y-axis = number of individuals gaining resources.
Egs of IDD? (2)
• Parsus major: woodland vs hedgerow.
• Red grouse.
Explain Parsus major? (3)
● Oak woodland is the best breeding habitat but is quickly occupied & becomes completely filled with territories.
● Filled Oak woodlands force excluded individuals to occupy hedgerows where there is less food & ultimately less breeding success.
● If birds are removed from the best habitat then the ones occupying the hedgerows move to the woodlands.
Expkain Red grouse?
Territorial birds defend the richest areas as breeding & feeding territories, resulting in excluded birds exploiting poor areas with low survival rate.
Harper 1982 paper summary? (3)
● An eg of IFD with unequal competitors.
● Population showed a distribution of ducks according to the IFD but some ducks were better competitors than others & grabbed most of the food.
● Therefore, there was unequal distribution of resources.
Habitat selection in stem mother aphids? (3)
● An eg of both IFD & IDD models.
● It first appears that females follow the IFD as there are more of them in large leaves & less of them in small leaves, and would each get an equal amount of juice but…
● We observe later on that females follow the IDD as well due to females located at the base of the leaf getting more juice than those located away from the base of the leaf.
IFD stands for?
Ideal Free Distribution.
IDD stands for?
Ideal Despotic Distribution.
Home range?
= an area that an individual uses for all their activities throughout their life.
Territory?
= an area occupied by an animal/group of animals from which others are excluded by aggression or threat.
Egs of IFD? (2)
• Milinski’s experiment.
• Armoured catfish.
Intraspecific competition?
= the competition between individuals of the same species for the same limited resources.
Intraspecific competition plays a role in…? (3)
• Population dynamics.
• The distribution of individuals within a habitat.
• The overall structure of ecosystems.
Intraspecific roles do what/importance?
Show us how an individual’s behaviour influences all other aspects of an ecosystem.
Intraspecific competition vs Interspecific competition?
● Intraspecific competition
= between the same species.
● Interspecific competition
= between different species.
Effects of Intraspecific competition on populations (linking to population ecology)? (2)
• Leads to regulation of population size.
• Leads to changes in the spatial distribution of individuals.
How does Intraspecific competition lead to the regulation of population size?
It’s because of competition limiting the number of individuals that can exist within a particular area.
IFD?
= model that describes how organisms distribute themselves among different resource patches in order to maximize their fitness.
IFD result based on “Ideal” or “Free” assumptions?
Enables individuals to make optimal decisions about where to forage or mate, based on the quality & availability of resources.
IFD importances? (3)
● Helps us understand how organisms distribute themselves in response to resource availability & competition.
● Helps us better understand the behaviour & ecology of different organisms.
● Helps us make predictions about how populations might respond to changes in their environment.
Milinski’s experiment? (4)
● Placed 6 sticklebacks in a tank with one side (A) of the tank receiving twice the rate of food than the other side (B).
● Observed that the fish partitioned themselves in a way that 4 fish went to side A & the remaining 2 went to side B.
● When the sides were inverted with more food at B & less at A, the fish partitioned themselves once more by 4 fish being at side B and 2 being at side A.
● Therefore, the fish were following IFD.
IDD assumption?
Certain individuals in a population are dominant & can monopolize access to resources.
IDD assumption result?
Dominant individuals will claim the best resources for themselves, while the subordinate individuals will be forced to occupy less desirable areas.
Explain graph of stem mother aphids? (4)
● Talks on the level of fitness of stem mother aphids in relation to the leaf size (quality) & the no. of stem mother aphids per leaf (no. of competitors).
● Found that in larger leaves, you would have more stem mother aphids who would fight for the mid-rib position on a leaf
● Whoever won would settle at the base of the mid-rib of the leaf where food was the richest, therefore increasing the fitness of that particular stem mother aphid.
●
Things to note based on answers given on Slido open ended question? (2)
• Consider costs & benefits relevant to that specific individual.
• Territorial behaviour of when B>C.
When should an individual show territorial behaviour (given costs & benefits)?
Only if B>C.
Explain graph of benefits & costs? (5)
● Speaks on the idea of economic dependability.
● As the amount of resource defence/territory size increases, costs of defense increase.
● • x-axis = Territory size.
• y-axis = Benefit or Cost.
● 2 benefit curves: one for rich environment, one for poor environment.
● If a benefit curve rises steeply, it means that the density of resources is high.
Eg of Benefits & Costs graph?
Golden winged sunbird with Leonotus flowers.
Eg of how changes in resource distribution patterns affect territoriality?
Plain zebra vs Grey’s zebra.
Explain eg of how changes in resource distribution patterns affect territoriality?
Grey’s zebra males establish territories around water holes as they tend to be concentrated with females compared to plain zebra which are not territorial.
List the scenarios? (3)
● S1
= Evenly spread, low quality resources.
● S2
= Localised, high quality resources.
● S3
= Highly concentrated, high quality, ephemeral resources.
Would you expect territoriality in S1?
No.
Would you expect territoriality in S2?
Yes.
Would you expect territoriality in S3?
No.
Why would/wouldn’t you expect territoriality in S1?
B<C.
Why would/wouldn’t you expect territoriality in S2?
B>C
Why would/wouldn’t you expect territoriality in S3? (3)
• B<C.
• Unpredictability.
• Feeding frenzy.
Eg of S1?
Grass.
Eg of S2?
Fruiting tree.
Eg of S3?
Swarm of insects.
Ephemeral?
= seasonal.
The problem with shared resource defense?
With more resources/abundance, you have more intruders.
Benefit of Shared resource defense?
There’s power in numbers when defending against intruders.
Cost of Shared resource defense?
Having to share resources, but will be minimum if resources are abundant.
Eg of Shared resource defense?
Pied wagtails.
Egs of Shared resource defense? (2)
• Pied wagtails.
• Brashares & Arceses paper (1999).
Defending a territory attributes? (2)
• Energetically expensive.
• Only favoured by selection when B>C.
Factors that may influence if an individual defends a territory or not? (5)
• Food quality.
• Food quantity/abundance.
• Mating partner(s) availability.
• Predictability of the movement of females.
• Presence of competitors.
Questions to ask regarding territorial behaviour? (2)
• Should an individual be territorial (given the costs & benefits)?
• If yes, what should the optimal territory size be?
Brashares & Arceses 1999 summary? (3)
Oliver et al 2007 summary? (3)
