topic 3 - density independent pop growth

Question 1

what is a model

Answer 1

• A simplified description, especially a mathematical one, of a system or process
Population growth model: a simplified mathematical description of population growth

Question 2

why do we use models?

Answer 2

○ Simplifies a complex process

Allows us to make projections regarding a process that cannot be observed directly

Question 3

consequences of assumpin closed pop

Answer 3

• Simple population growth models assume populations are closed
○ Emigration and immigration are difficult to model
In many populations, growth is governed primarily by birth and death rates

Question 4

BD model?

Answer 4

Nt+1 = Nt +B-D

Question 5

two principles of DI pop growth

Answer 5

Without density dependent feedback, populations grow exponentially or geometrically (density independent)
- • Rate of growth/slope continuously increases

Natural populations will eventually show self-limitation (density dependence)

Question 6

when do pops grow exponentially or geometrically

Answer 6

ccurs when resources are not limiting (space, food, etc)
○ Characteristic of populations at low densities in favorable environments
○ Commonly occurs when an organism invades a new habitat
○

Question 7

why do natural pops show self limitation

Answer 7

2. Natural populations will eventually show self-limitation (density dependence)
   ○ Populations cannot increase indefinitely
   ○ Resources eventually become limiting influencing b and d
   Population growth rates eventually decline

Question 8

types of density independent growth?

Answer 8

discrete model - geometric

cont. mmodel - exponential growth

Question 9

models of d-d growth

Answer 9

discrete and cont. logistic growth

Question 10

what is discrete time?

Answer 10

*

* Discrete - defined times, usually linked to the organisms e.g. reproduction times

Question 11

look at D-I vs D-D graphs

Answer 11

ok