Why Is Exponential Growth Unrealistic?

Why is exponential growth unrealistic? Mark A. McGinley Honors College and Department of Biological Sciences Texas Tech University

Exponential growth assumes that per capita growth rate (r) is constant r r time N

Exponential growth ,[object Object],[object Object],[object Object],[object Object]

What is a realistic relationship between per capita growth rate and population size? ,[object Object],[object Object],[object Object]

How should the per capita birth rate be influenced by population size? ,[object Object],[object Object],[object Object],[object Object],[object Object]

Per capita birth rates ,[object Object],[object Object],b N

How should the per capita death rate be influenced by population size? ,[object Object]

How should the per capita death rate be influenced by population size? ,[object Object],[object Object]

How should the per capita death rate be influenced by population size? ,[object Object],[object Object],[object Object],[object Object]

Per capita death rates ,[object Object],[object Object],d N

Let’s review ,[object Object],[object Object],[object Object],[object Object],[object Object]

How should the per capita growth rate be influenced by population size? ,[object Object],[object Object],[object Object]

Plot both lines on the same graph b N b d d

r = b - d b N b d d Because r = b – d, r can be found my measuring the distance between b and d for any value of N (shown in red- when the arrow points up r is positive and when the arrow points down r is negative)

What does this mean? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Carrying Capacity ,[object Object],[object Object],[object Object],[object Object],[object Object]

We are now ready to plot r vs N (the more realist relationship) ,[object Object],r N r max k 0

r max ,[object Object],[object Object],[object Object],[object Object]

What is a realistic relationship between per capita growth rate and population size? ,[object Object]

Note ,[object Object],[object Object],[object Object],[object Object]

Why Is Exponential Growth Unrealistic?

Recommended

Recommended

More Related Content

More from Mark McGinley

More from Mark McGinley (20)

Recently uploaded

Recently uploaded (20)

Why Is Exponential Growth Unrealistic?