NRS305 Final Exam
2024./2025 100% VERIFIED
ANSWERS
Population regulation is a term that emerged from the earliest decades of the wildlife ecology
discipline. What does population regulation mean?
Keeping populations from getting out of control.
Naturally, populations are regulated in the wild by K because they never grow exponentially.
How did the examples of whooping cranes, bighorn sheep in the Western US, Vancouver marmots,
white sharks, and New England cottontails illustrate the different ways in which population
regulation is important in wildlife management and conservation?
Whooping cranes have low chick survival rates.
Bighorn sheep populations are struggling, how do you boost populations? Predator regulation?
Vancouver marmots extremely low population, facing regular predation rates.
New England cottontail reintroduction programs threatened by predation.
For many issues in wildlife ecology, the primary focus is on top-down influences (effects of the
predators on prey). This is especially the case with news stories in the popular press, in which
vertebrates that consume other vertebrates get more attention than organisms at lower trophic
levels. What is responsible for the disproportionately strong focus on predators and predation
compared to other factors that regulate populations?
Predators dominate top of food chains, but are populations at lower levels kept below K by
consumption from above? There is top down bias, because we are predators.
Predators pose conservation and management problems, but lack of predators can also be a big
problem (anti-predator adaptations).
Evolutionary importance of predators is obvious.
In the case of white-tailed deer in non-farmland-dominated regions of Wisconsin, a decline in deer
populations coincided with the growth of the wolf population in the state; this could
, understandably lead some people to think that deer populations were being regulated by wolf
predation. What were some alternative explanations for the apparently negative relationship
between deer and wolf densities in non-farmland-dominated regions of Wisconsin?
Deer population boom and bust was unrelated to wolves.
-Increased hunting from humans
-Increased antler collection
-A more violent winter
-Food webs
What is it about real systems in nature that contradict the oftentimes simplistic view of the density
or behavior of a predator being the most important factor in explaining the density or distribution
of a prey species? Also, what variables would you need to measure (and what data would you
need to collect) to test the hypothesis that predation is an important regulator of a prey
population?
-immigration, emigration, carrying capacity
-food chains part of much larger food web, many predators rely on the same prey
-Stochastic events
-Distribution of a prey species due to the distribution of their food
In the simplest model of the predator density being regulated by prey density, the growth of the
predator population is constrained only by its own death rate and which variables are associated
with the prey? (On the exam you will be given the equation with one of the variables blacked out)
dP/dt = acRP - dP
P: # predators
R: # prey
a: efficiency of conversion of food to growth (how well prey converts to new predator)
c: constant for efficiency of predation (how well predators deplete prey)
d: constant for death rate of predators
This simple model (for the predator) assumes what about the predator's feeding behavior and
food requirements? What is it about real predators in nature that makes this assumption
unrealistic?
2024./2025 100% VERIFIED
ANSWERS
Population regulation is a term that emerged from the earliest decades of the wildlife ecology
discipline. What does population regulation mean?
Keeping populations from getting out of control.
Naturally, populations are regulated in the wild by K because they never grow exponentially.
How did the examples of whooping cranes, bighorn sheep in the Western US, Vancouver marmots,
white sharks, and New England cottontails illustrate the different ways in which population
regulation is important in wildlife management and conservation?
Whooping cranes have low chick survival rates.
Bighorn sheep populations are struggling, how do you boost populations? Predator regulation?
Vancouver marmots extremely low population, facing regular predation rates.
New England cottontail reintroduction programs threatened by predation.
For many issues in wildlife ecology, the primary focus is on top-down influences (effects of the
predators on prey). This is especially the case with news stories in the popular press, in which
vertebrates that consume other vertebrates get more attention than organisms at lower trophic
levels. What is responsible for the disproportionately strong focus on predators and predation
compared to other factors that regulate populations?
Predators dominate top of food chains, but are populations at lower levels kept below K by
consumption from above? There is top down bias, because we are predators.
Predators pose conservation and management problems, but lack of predators can also be a big
problem (anti-predator adaptations).
Evolutionary importance of predators is obvious.
In the case of white-tailed deer in non-farmland-dominated regions of Wisconsin, a decline in deer
populations coincided with the growth of the wolf population in the state; this could
, understandably lead some people to think that deer populations were being regulated by wolf
predation. What were some alternative explanations for the apparently negative relationship
between deer and wolf densities in non-farmland-dominated regions of Wisconsin?
Deer population boom and bust was unrelated to wolves.
-Increased hunting from humans
-Increased antler collection
-A more violent winter
-Food webs
What is it about real systems in nature that contradict the oftentimes simplistic view of the density
or behavior of a predator being the most important factor in explaining the density or distribution
of a prey species? Also, what variables would you need to measure (and what data would you
need to collect) to test the hypothesis that predation is an important regulator of a prey
population?
-immigration, emigration, carrying capacity
-food chains part of much larger food web, many predators rely on the same prey
-Stochastic events
-Distribution of a prey species due to the distribution of their food
In the simplest model of the predator density being regulated by prey density, the growth of the
predator population is constrained only by its own death rate and which variables are associated
with the prey? (On the exam you will be given the equation with one of the variables blacked out)
dP/dt = acRP - dP
P: # predators
R: # prey
a: efficiency of conversion of food to growth (how well prey converts to new predator)
c: constant for efficiency of predation (how well predators deplete prey)
d: constant for death rate of predators
This simple model (for the predator) assumes what about the predator's feeding behavior and
food requirements? What is it about real predators in nature that makes this assumption
unrealistic?
