Unit 8: Topic 4 - Effect of Density of Populations Flashcards
What is the carrying capacity?
The carrying capacity is the average population determined by the balance between how many organisms an environment can support based on the resources available.
What determines the carrying capacity?
The carrying capacity is determined by a number of environmental factors such as food availability, shelter availability, water availability and the ability to mate.
What are the two different types of growth models and when are each produced?
The two types of growth models are the exponential growth model and the logistic growth model. The exponential growth model is for when the population is not yet limited by environmental factors. The logistic growth is the growth in population when there is a set carrying capacity.
What are density-dependent and density-independent factors?
Density-dependent factors are factors that depend on the size of the existing population. For example, food availability and disease would be density-dependent factors since the amount of food available and the amount of disease spread would depend on whether there were a lot of organisms of the species or only a few. However, density-independent factors do not depend on the population. Such an example would be a natural disaster.
What is the relationship between density-dependent and independent factors and population growth?
When a population starts, it exponentially grows and there is a surplus of resources. This growth continues until the population reaches the carrying capacity and the density-dependent factors cause a decrease in population. This decrease can be caused by famine or the decrease in reproduction until the population is under the carrying capacity. Then, this cycle happens again.
What is the formula for carrying capacity and how is it used?
(dN) / (dt) = rN (1 - N/K) where:
dt = change in time
N = population size
rmax = maximum per capita growth rate
of population
K = carrying capacity
