chapter 13 Flashcards
All populations experience fluctuations due to
availability of resources, predation, competition, disease, parasites, and climate.
what allows larger organisms to maintain homeostasis in the face of unfavorable environmental changes.
Larger organisms have a lower surface-area-to-volume ratio
What can the age structure of a population tell us about pop. fluctuations over time?
It can show times of particular growth or decline in previous years.
When an age group contains a high or low number of individuals, the population likely experienced
high birth or death rates in the past.
when a population grows beyond its carrying capacity; often occurs when the carrying capacity of a habitat decreases from one year to next (e.g., because less resources are produced).
Overshoot
a substantial decline in density that typically goes well below the carrying capacity.
Die-off
regular oscillation of a population over a longer period of time.
Population cycles
Cyclic populations can occur among
related species and across large geographic areas
Populations are stable at their
carrying capacity
Why are some pops. inherently cyclical?
There is a delay between the time of breeding and the birth of offspring.
when density dependence occurs based on a population density at some time in the past.
Delayed density dependence
r =
intrinsic growth rate
N =
current population size at time t
K =
carrying capacity
dn
____=
dt
rate of change in population size
How can energy reserves make a pop. experience delayed density dependence?
They enable the population to survive above carrying capacity.
Delayed density dependence may occur because the
organism can store energy and nutrient reserves.
When populations are low and food is abundant, the water flea Daphnia galeata stores surplus energy as lipid droplets.
is an example of
Delayed density dependence
Delayed density dependence can occur when there is a
time delay in development from one life stage to another.
Small populations are more vulnerable to extinction
than larger populations.
Which is an example of demographic stochasticity?
low fertility for some individuals
variation in birth rates and death rates due to random differences among individuals
Demographic stochasticity
variation in birth rates and death rates due to random changes in the environmental conditions
Environmental stochasticity
the process of breaking up large habitats into a number of smaller habitats.
Habitat fragmentation
high-quality patches that produce a large number of individuals that disperse to other patches
Sources
low-quality patches that produce few individuals and rely on dispersers to keep the sink population from going extinct.
Sinks
We can increase the number of occupied habitat patches by providing
corridors between patches to increase the rate of colonization (c).
We can also increase the number of occupied patches by
decreasing rates of extinction (e).
Dispersal success is inversely related to
the distance of dispersal;
refers to the dispersal between source and sink populations.
) The rescue effect
when dispersers supplement a declining subpopulation and thereby prevent it from going extinct.
Rescue effect
