Interactions Among Living

OrganismsPage 539-549Chapter 18

Section 2 & 3

Identify the characteristics that describe

populations.

Examine the different types of relationships that occur among populations in a community.

Determine the habitat and niches of a species in a community.

Objectives for Section 2

Population Size

Number of individuals in the population Difficult to measure

Small populations that are made up of organisms that do not move are determined by counting the individuals.

Usually individuals are too widespread or move around too much to be counted.

Characteristics of Populations

What does this graph tell

us?

Change in population size due to-

Older mice die Mice are born Mice eaten by predators Some mice move away

Is this a fast changing population size or slow?

What happens if you observe Field Mice in a pasture for

several months?

What have you noticed about the Pine Trees

here in Kentucky over the last several years? Has this effect been fast or slow?

How can Pine Tree population be effected more quickly? Forest Fire? Disease? Logging?

Pine Trees in a Mature Forest

The number of individuals in a population that

occupy a definite area

Example: 100 mice live in an area of 1 square kilometer,

the population density is 100 mice per square kilometer.

Population Density

Population Density

Map

How the organisms are arranged in a given

area Can be:

Evenly spaced Consistent distance between them

Randomly spaced Wind or birds dispersing seeds

Clumped together Resources such as food or living space are clumped Results when animals gather in groups or plants

grow near each other in groups

Population Spacing

Population Spacing

What are the five limiting factors from the

video below?

http://www.youtube.com/watch?v=CuwrZUTeEqM

Limiting Factors

Any abiotic or biotic factor that limits the number of

individuals in a population A limiting factor can affect other populations in the

community indirectly: Example:

A drought might reduce the number of seed-producing plants in a forest clearing. Fewer plants means that food can become limiting factor for deer that eat the plants and for a bird population that feeds on the seeds of these plants. Food also could become a limiting factor for animals that feed on the birds.

Limiting Factors

Lets go outside!!!!

Limiting Factor Example

Get out worksheet:

Key Terms Interactions of Living Things

Bell Ringer 1-10-13

Open Book to Pages 541-543

Each group is responsible for the section they are assigned. Include Key Term Definition Explanation of the section must be presented

to class, so they can put in their notes!

Group Presentations