Population Ecology + Demography
What does the Type II survivorship curve represent?
Species with a constant rate of death over an individual's lifespan
List three factors involved in density-dependent regulation.
Resource limitation, territoriality, disease, predation, toxic wastes, intrinsic factors, etc.
Give an example of a factor that could influence an environment's carrying capacity.
Ex: access to shelter, predation pressure, nutrient availability, access to water, access to suitable nesting sites
What is the difference between population density and population dispersion?
Population density is the number of individuals per unit of area or volume within a geographical boundary.
Population dispersion is the pattern in space regarding the number of individuals within the geographical boundaries.
What is population dynamics?
The study of how populations change in size over time and what biotic and abiotic factors contribute to that variation
What does this equation represent?
dN/dt = rmax N((K − N)/K)
Carrying capacity or logistic population growth
Which processes contribute to a population's density?
Processes that add individuals (ex: birth) and processes that remove individuals (ex: death) contribute to a population's density.
Explain boom-and-bust cycles with an example.
Populations can go through boom-and-bust cycles (a period of high population density followed by a period of low population density).
Ex: voles and lemmings have 3-4 year cycles, birds have 9-11 year cycles, lynx have 10 year cycles, etc.
In relation to carrying capacity, what does N mean and what does K mean?
N refers to the total number of individuals now.
K refers to the maximum stable population size that a particular environment can support.
Describe clumped dispersion with an example.
Individuals live in groups, like wolves who clump together to hunt more effectively
Describe an example of how emigration and immigration affect a metapopulation.
A butterfly species exists as a metapopulation across a set of islands, so individuals are constantly moving back and forth between different populations. Because local populations can be occupied or unoccupied at any given time, there might be local extinctions followed by recolonizations.
When is population growth the largest?
When the number of individuals is half the carrying capacity, population growth is the largest.
How is annual per capita birth rate calculated?
The number of births per year divided by the number of individuals in the population
Explain the first hypothesis proposed to explain the lynx/hare cycles.
Variation was caused by food shortage in the winter, which triggers a population crash among hares. This crash triggers further effects up the food chain, affecting lynx populations.
What is the difference between semelparity and iteroparity?
Semelparity involves an individual producing a large number of offspring once and then dying.
Iteroparity involves an individual producing a small number (usually 1) of offspring multiple times throughout their life.