160 likes | 286 Views
Interactions Among Living Organisms. Page 539-549 Chapter 18 Section 2 & 3. Objectives for Section 2. Identify the characteristics that describe populations. Examine the different types of relationships that occur among populations in a community.
E N D
Interactions Among Living Organisms Page 539-549 Chapter 18 Section 2 & 3
Objectives for Section 2 • 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.
Characteristics of Populations • 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.
What happens if you observe Field Mice in a pasture for several months? • 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?
Pine Trees in a Mature Forest • 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?
Population Density • 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 Spacing • 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
Limiting Factors • 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 Factor Example • Lets go outside!!!!
Bell Ringer 1-10-13 • Get out worksheet: • Key Terms • Interactions of Living Things
Group Presentations 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!