Chapter 11 Flashcards
When experimental plants were grown at high densities…
the proportion of resources allocated to leaf production increased
Which of the following factors is most likely to be density-independent regulator of population growth?
drought
Self-thinning occurs…
at high population densities
In a wolf pack, the beta male is
closely related to the alpha male
Which of the following is a density-independent factor?
a. weather event
b. shelter availability
c. availability of mates
d. food availability
a. weather event
The carrying capacity is the population size at which dN/dt is…
equal to 0
Which of the following is negatively correlated with territory size?
a. number of mates
b. bird density
c. bird size
d. number of offspring
b. bird density
When individuals in a small population have difficulty finding a mate, this is referred to as…
the Allee effect
The inidivudlas that disperse as a response to high population density are generally
the younger members of the population
The model dN/dt = (b-d)N makes 2 assumptions:
there is unlimited essential resources
there is a constant environment.
What is carrying capacity, and what is its variable?
When birth rate = death rate. Represented by K
What does K/2 represent
1/2 of the carrying capacity. This is where the fastest rate of growth is occurring.
What formula takes into account carrying capacity?
dN/dt = rN(1-N/K)
What do the variables represent for the carrying capacity formula?
dN - change in population
dt - change in time
r - growth rate
N - population size
K - carrying capacity
Define density-dependent mortality
Rate of mortality increases as population density increases.
Why does mortality increase as population increase? (3)
- reduced resource availability
-changes in predation pattern
-spread of disease and parasites
Define density-dependent fecundity
Rate of fecundity decreasing as population density decreases.
*Doesn’t have to kill you to reduce fecundity.
Define competition
When individuals use a common limited resource. Not enough of a resource for all individuals
Define intraspecific
Competition among individuals of the same species. Typically happens due to the same species having very similar resource requirements.
What does competition for resources at high population densities cause?
Can suppress individual growth and reduce survival.
What happens to growth rate and phenotypic plasticity in high-density populations?
Growth rate decreases.
Competition-induced phenotypic plasticity occurs.
Define phenotypic plasticity
The ability of organisms with a given genotype to develop varying phenotypes under fluctuating environmental conditions.
Define self-thinning and what it is caused by.
Individuals of a species dying off and leaving more room for the remaining individuals to grow. Caused by the combined effect of a density-dependent mortality and growth within a population. As density declines, growth of remaining individuals increases.
How do plants self-thin? animals?
Plants do this by outcompeting and causing others to die (think if a plant grows taller quicker it will block sunlight for other plants)
Animals do this through dispersal.
How does competition reduce fecundity?
A greater population density results in a higher age at first reproductive event. Higher age is a result of limited resources causing an organism to spend longer times in the growth & development phase.
What does stress cause? (5)
-Suppression of growth
-Curtails reproduction / delays sexual activity
- Makes individual more vulnerable to disease
-Increases fetal mortality
-Reduced milk production resulting in stunted growth of their young
How does a high density affect dispersal?
Lack of resources can cause individuals to disperse or cause sub-adults to be driven out of the area by adult aggression.
Define Social Behavior
The degree to which individuals of the same species tolerate each other.
What does social behavior limit?
Limits the number of animals living in the same habitat with a common food supply
How are social groups typically organized? What are it’s 2 opposing forces?
Based on aggression, intolerance, and domination of one individual by another. Made up of 2 opposing forces:
-Mutual attraction of individuals
-Need for individual space
Define Home Range
Area that an animal normally uses over the course of a year
What causes the size of a home range to vary?
-food availability
-mode of food gathering
-body size
-metabolic needs
