Title: Lecture 21-11: Insect Population Dynamics 1
Date: 2021-09-27 12:45
Tags: lecture

## Exponential Growth Model

* Also referred to as the Malthusian growth model. Thomas Malthus introduced this model in *An Essay on the Principle of Population* published in 1798.
* The exponential growth model assumes unlimited resources such as food and space.

dN/dt = rN

where:

*  r is the intrinsic growth rate: (births - deaths)/N
*  N is the population size

[Exponential Growth (YouTube; 10 minutes)](https://www.youtube.com/watch?v=c6pcRR5Uy6w)

References: [Wikipedia: Exponential Growth](https://en.wikipedia.org/wiki/Exponential_growth),
[Wikipedia: Malthusian growth model](https://en.wikipedia.org/wiki/Malthusian_growth_model)

## Logistic Growth Model

* Also referred to as the Verhulst growth model. This model was developed by Pierre Verhulst in 1838, after he had read Malthus' essay.
* The logistic model assumes that resource availability limits the number of individuals in a population to constant K, the **carrying capacity**.

dN/dt = rN *(K-N)/K

where:

* r is the instrinsic growth rate
* K is the carrying capacity, the maximum population size that can be sustained by the environment

[Logistic Growth (YouTube; 11 minutes)](https://www.youtube.com/watch?v=rXlyYFXyfIM)

Reference: [Wikipedia: Logistic Growth]()

## r and K Selection

* r selected organisms produce many offspring = a high reproduction rate (r)
* K selected organisms produce few offspring, but put significant resources into ensuring their survival

[r/K Selection(YouTube; 7 minutes)](https://www.youtube.com/watch?v=Bu6ouKt9zhs)

Reference: [Wikipedia: r/K Selection Theory](https://en.wikipedia.org/wiki/R/K_selection_theory)