How does the logistic population growth model differ from the exponential growth model in terms of resource limitations and population size regulation?
The logistic population growth model accounts for environmental limitations by incorporating a carrying capacity (k), which acts as a cap on population size. As the population approaches k, growth slows and eventually stops, resulting in a sigmoidal (S-shaped) curve. In contrast, the exponential model assumes unlimited resources and allows for continuous, unregulated population growth.
What role does the carrying capacity (k) play in the logistic population growth model, and how does it affect population growth as the population size approaches k?
The carrying capacity (k) represents the maximum population size that an environment can sustain. In the logistic model, as the population size (n) approaches k, the growth rate decreases due to increased competition for limited resources. When n reaches k, population growth stops, preventing the population from exceeding sustainable limits.
What is the main difference between the logistic and exponential population growth models regarding resource limitations?
The logistic model accounts for environmental limitations by incorporating a carrying capacity, while the exponential model assumes unlimited resources and no cap on population size.
How does the carrying capacity (k) affect population growth in the logistic model as the population size approaches k?
As the population size approaches k, the growth rate slows down and eventually stops, preventing the population from exceeding the carrying capacity.
What shape does the logistic population growth curve typically exhibit, and why?
The logistic growth curve is sigmoidal (S-shaped) because growth is initially rapid but slows as the population nears the carrying capacity.
What mathematical term is added to the exponential growth equation to create the logistic growth equation?
The term (1 - n/k) is added, where n is population size and k is carrying capacity, to account for environmental limitations.
At what population size does the logistic model reach its peak instantaneous growth rate, and what happens after this point?
The peak instantaneous growth rate occurs when the population size is half the carrying capacity (n = k/2); after this, the growth rate decreases as n approaches k.
How does the per capita growth rate (r) behave in the logistic model compared to the exponential model?
In the logistic model, the effective per capita growth rate decreases as population size increases, while in the exponential model, it remains constant.
What happens if a population temporarily exceeds its carrying capacity in the logistic model?
If the population exceeds k, the growth rate becomes negative, causing the population to decrease back toward or below the carrying capacity.
Which population growth model considers density-dependent factors, and what is the significance of this consideration?
The logistic model considers density-dependent factors, which allows it to realistically model population regulation due to limited resources.