Question 1

The observation that three species of grouse in Finland all experience natural population cycles every 6-7 years in synchrony is evidence that

Accepted Answer

The fact that three different species of grouse in Finland all experience population cycles in synchrony suggests that drivers of these population cycles can happen over a large area, affecting multiple species. This is evidence of how environmental factors can impact populations and communities beyond individual species. It is not evidence of close relatedness, convergent evolution, or equal impacts from climate change.

Question 2

When comparing larger animals to smaller animals we tend to see more stable population sizes in larger animals. What might be a reason this is the case?

Accepted Answer

Larger animals have longer generation times and lower reproductive rates, which means that their populations are less responsive to environmental changes and can more steadily maintain a stable population size. Smaller animals, on the other hand, have shorter generation times and higher reproductive rates, which means that their populations can fluctuate more drastically in response to environmental stochasticity.

Question 3

When a population is small there is an abundance of resources for all individuals, so the per capita resource availability is high, thus leading to more rapid growth rates (as compared to larger populations). Why then are small populations more likely to go extinct compared to large populations?

Accepted Answer

Small populations are more impacted by stochastic events, which can include natural disasters, diseases, and fluctuations in resource availability. These events can have a greater impact on smaller populations with fewer individuals to buffer against the effects. In contrast, large populations are more resilient to these events as they have a greater genetic diversity and a larger number of individuals to withstand the effects of fluctuations in resources or environmental conditions. Therefore, small populations are more likely to go extinct due to stochastic events.

Question 4

A population that exceeds its carrying capacity will

Accepted Answer

When a population exceeds its carrying capacity, it means resources are being consumed faster than they are being replenished. This leads to increased competition, which can result in decreased birth rates, increased death rates, and emigration. These factors can eventually cause the population to decline, sometimes even below the carrying capacity, as resources are depleted or destroyed at an unsustainable rate. Therefore, the most likely scenario is that a population that exceeds its carrying capacity will continue to increase for a time but then die back to below the carrying capacity.

Question 5

Which of the following is NOT true about the 1911 St. Paul Island, Alaska, reindeer introduction?

Accepted Answer

The reindeer numbers on St. Paul Island crashed primarily due to overgrazing and the harsh winters, not because they relied on the same food item throughout the entire year.

Question 6

That a predator finds itself in an environment with increased prey, yet does not immediately convert the prey consumed in such a resource-rich environment into offspring is the foundation for the idea of

Accepted Answer

Delayed density dependence describes the phenomenon where, in a resource-rich environment, a predator may not immediately convert prey consumed into offspring. Instead, it may take time for the population to reach equilibrium due to a lag in the effects of density-dependent factors. Overshoot and die-off refers to the boom-and-bust cycles of a population when it exceeds the carrying capacity of its environment. Extinction modeling involves predicting the probability of a species going extinct based on various factors. Metapopulation dynamics refer to the interactions between multiple populations of a species in different habitats.

Question 7

Which of the following is NOT a factor that determines whether a patch is likely to be occupied by a species?

Accepted Answer

The size of the patch, proximity to other occupied patches, and resource availability in the patch are all factors that can influence a species' decision to occupy a patch. However, the history of extinction in the patch is not a factor that determines whether a patch is likely to be occupied by a species.

Question 8

Vernal pools are ephemeral bodies of water that form in small depressions within the forested landscape during early spring in the northeastern United States (as well as elsewhere). The water in the vernal pools has its origin with winter snowmelt and spring rains. These vernal pools are important breeding grounds for some amphibian species. Describe how environmental stochasticity might influence amphibian populations at vernal pools.

Accepted Answer

The answer of Vernal pools are ephemeral bodies of water...

Question 9

Describe what is meant by delayed density dependence.

Accepted Answer

The answer of Describe what is meant by delayed density...

Quiz 13: Population Dynamics Over Space and Time