Population Ecology Notes

Population ecology

1. Populations can be described according to certain characteristics.

- size of population

- spacing (how organisms are arranged in a given area)

- density – how many individuals there are in a specific area

Population Density

2. The size of a population occupying an area of a specific size is called population density

- the more individuals = more dense of a population

- less individuals = less dense of a population

Limiting Factors

3. Limiting factor – any biotic or abiotic factor that restricts the number of individuals in a population - examples: food, temperature, living space, other resources - populations cannot grow uncontrolled forever - what affects one population can affect others living in same area

Competition

4. Competition – contest among organisms to obtain the resources they need to survive and reproduce

- population density increases = increase in competition

Carrying Capacity

5. Carrying capacity – the largest number of individuals an environment can support and maintain for a long period of time

- when this happens – some individual may not be able to compete, and will die or have to find another place to live

Carrying capacity

Biotic Potential

6. Biotic potential – the number of individuals each female of a population can produce under the best possible conditions

- plenty of food and shelter

- ideal weather, no disease or enemies

- populations never reach biotic potential in the wild

7. Niche and habitat

1. Niche – all of an organism’s relationships with its environment (both biotic and abiotic factors)

a. Relationships with others, its offspring, time of day its most active, and where it finds shelter

b. An organism’s “lifestyle” – how it contributes to and fits into its environment

2. Habitat – the actual place an organism lives

Questions

1. How is habitat and niche different?

2. Give some examples of things that will limit a population’s growth?

3. What is the carrying capacity of a population?

4. What are the three characteristics used to describe populations?