# Topic 15 Flashcards

Exponential model of population growth is based on several assumptions about the environment which are.

- assumes that essential resources, space, food, are all unlimited
- assumes constant environment w no seasonality or variations or change of any kind

In real world environment isn’t constant and resources almost always become..

limiting if population numbers reach large sizes. b and d rate will change, and r value will change

Assume population is growing exponentially ..

- resources are initially high
- higher density demand for resources
- resource consumption eventually exceeds rate of resupply
- shrinking resources and unequal distribution of resources (increase morality and fewer offspring/individual)

Due to density-dependence, we should expect ..

r (=b-d) to vary with N (assumption of exponential model is that r is constant)

K=

carrying capacity, population size (N) that the environment can carry or support

Carrying capacity

max number of individuals an environment can support indefinitely. resources not unlimited

When N=K, r=0

population is not decreasing just at as much as it can hold

K acts as an..

equilibrium around which a population will fluctuate .

Population below K

increase

Population above K

decrease

Determining K is difficult as it will not necessarily ..

remain the same over time

From equation for exponential growth we can do math to arrive at an equation that incorporates ..

K

Logistic growth equation

∆N/∆T = rN(1-N/K)

As the population reaches the carrying capacity the rate of growth stop and if the population exceeds the K the population growth becomes..

negative

(1- N/K) is a correction factors added to the

exponential growth model