A population is a group of individuals of a single species living in an area at the same time.
Population ecology is the study of how population size and age distribution change over time through interactions with the environment and individuals from their own species as well as others.
The carrying capacity is the maximum population size allowed by the resources in a habitat.
Exponential growth models are independent of population density and follow a J-shaped curve. Logistic growth is limited by carrying capacity therefore depends on the population density. Since population growth slows down near carrying capacity, logistic growth curves are S-shaped.
Mathematical models of population growth allow estimation of population sizes in various situations. For instance, we can calculate changes in predator and prey populations. Moreover, they are useful to estimate how populations will fare when outside influences (habitat loss, climate change, etc.) affect variables such as growth rate. In addition, scientists can calculate growth of invasive species as well as how native species will be affected.
