19. Community ecology: competition

Question 1

Life expectancy, eₓ on x axis

Answer 1

expected years of life left to an individual of age x

Question 2

Reproductive value, vₓ

Answer 2

expected number of future daughters left to an individual of age x

Question 3

IntRA-specific competition

Answer 3

competition among
members of the same species (among
conspecifics)

Question 4

IntER-specific competition

Answer 4

competition among
members of different species (among
heterospecifics)

Question 5

Scramble/explosive competition

Answer 5

depletion of a
shared resource (squirrels and birds)

Question 6

Contest/ interference competition

Answer 6

direct interactions, such as battles over territory (invasive ants and native ants)

Question 7

Lotka-Volterra equations for intra specific

Answer 7

for 1 species competing for resources (logistic model= 1 eqauation)

Question 8

Lotka-Volterra equations for inter specific

Answer 8

for 2 species competing for resources (logistic models= 2 eqauation)

Question 9

Principle of competitive exclusion

Answer 9

In other words, two species can’t compete too intensely (i.e., overlap too much in resource use/niche space), or one will out-compete the other

Question 10

equilibrium for a population

Answer 10

population size not changing over time (dN/dt= 0)

Question 11

equilibrium for a community

Answer 11

a community not changing over time

Question 12

equilibrium in the strict sense

Answer 12

all populations in a community at equilibrium

Question 13

Stability

Answer 13

the ability of a system to return to equilibrium following a perturbation or disturbance

Question 14

Coexistence requires…

Answer 14

intra specific (same species) competition be stronger than interspecific (different species) competition

Question 15

Coexistence

Answer 15

Occurs when two or more species have non-zero population sizes at equilibrium

Question 16

MacArthur’s warblers: classic
example of niche partitioning

Answer 16

• Warblers coexist by partitioning resources; they feed in different parts of trees; similar species have different niches

Question 17

Lotka-Volterra models too simple, ignore too much reality, including:

Answer 17

Most real communities are not at a competitive equilibrium