- By
**guang** - Follow User

- 159 Views
- Uploaded on

Download Presentation
## PowerPoint Slideshow about 'Populations' - guang

**An Image/Link below is provided (as is) to download presentation**

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

### Populations

Topic 5.3

Assessment Statements

- 5.3.1 Outline how population size is affected by natality, immigration, mortality and emigration.
- 5.3.2 Draw and label a graph showing a sigmoid (S-shaped) population growth curve.
- 5.3.3 Explain the reasons for the exponential growth phase, the plateau phase and the transitional phase between these two phases.
- 5.3.4 List three factors that set limits to population increase.

Outline how population size is affected by natality, immigration, mortality and emigration.

- Natality – # of new members of the species due to reproduction
- Mortality - # of deaths
- Immigration – members arriving from different places
- Emigration – members leaving the population

Mount Saint Helens 1980

- How is/was the sizes of populations affected by:
- Natality?
- Mortality?
- Immigration?
- Emigration?

Draw and label a graph showing a sigmoid (S-shaped) population growth curve.

Sigmoid (S-shaped) curve of the graph shows three stages in population growth

- Exponential growth phase – a.k.a. logarithmic phase, in which the # of individuals increases at a faster and faster rate
- Transitional phase – growth rate slows down considerably
- Plateau phase – stationary phase, in which the # of individuals has stabilized

Causes of exponential phase

- Plentiful resources
- Little or no competition from other inhabitants
- Favorable abiotic factors
- Little or no predation or disease

Causes of the transitional phase

- Increasing competition for resources among individuals of population
- Predators, attracted by a growing food supply, move into the area
- b/c of large numbers of individuals living together in a limited space, opportunities for disease to spread within the population increase

Causes of the plateau phase

- Less and less space
- Limited supply of food, animals tend to have smaller numbers of offspring
- Predators and disease increase mortality and the growth curve tends to level off
- # of births plus the # of immigrants is balanced with the # of deaths plus the # of emigrants

List three factors that set limits to population increase.

- The maximum number of individuals that a particular habitat can support is called the carrying capacity and it is represented by the letter K.
- Limiting factors:
- Availability of resources
- Build-up of waste
- Predation
- Disease

Download Presentation

Connecting to Server..