Topic 18 -Intraspecific Competition Flashcards
Intraspecific competition
an interaction between individuals of the same species (intra) brought about by a shared requirement for a resource in limited supply
intraspecific competition results in
reduced survival, growth and/or reproduction of some individuals
possible reproduction in fitness
competition acts as a selection pressure in nature
Types of competition
Exploitation (scramble) competition
Interference (Contest) Competition
Exploitation (Scramble) Competition
an individual responds to a decreased level of a limited resource remaining after it has been exploited by other individuals
individuals do not interact directly
Interference (Contest) Competition
an individual actually prevents another individual from exploiting a limited resource within a portion of the habitat
individuals interact directly
decrease net energy gain:
energy loss increase +/or energy gain decrease (individual basis)
low competition results in
reduced growth
moderate competition results in
reduced growth and reproduction
high competition results in
reduced growth, reproduction and survival
consumption rates decrease with…
increasing numbers of competitors, it is density dependent
Aggregative response=
what is it due to?
what does it involve?
what can it lower?
predators concentrate where prey density is high
due to high consumption rates
competitive interactions
can lower consumption rates
T or F patch with highest prey density is not always best
True
what are the model assumptions for ideal free distribution? (5)
1) There are a number of prey patches that vary in quality
2) Competitors are “free” to exploit all patches (can move freely among patches)
3) Individual prey consumption rates decline with increasing numbers of competitors in the patch
4) Individuals have equal competitive abilities
5) Animals distribute themselves “ideally” among patches to obtain highest consumption rates (maximize net energy gain to ensure high fitness)
At the equilibrium distribution the consumption rates of individuals are….
can be a dynamic equilibrium…
equal for all competitors in all patches
individuals are constantly moving between all patches, but individuals in the lowest quality patch will not gain access to more prey if they move to a higher quality patch
Ideal free distribution Harper 1982, what did this study do?
pre-cut bread to feed to ducks and fed at two different feeding stations to predict IFD.
One trial food was split evenly, ducks moved to each station 50/50, after 80s stabilized as predicted
the next was double at one station, twice the amount of ducks was at the double food station than the other, after 60s stabilized as predicted
