1. Population Ecology 4
CHAPTER
Placeholder opening page, but maybe we can duplicate the look of the SE chapter opener page by using the same fonts and colors (and maybe that Ch 14 icon?)

2. Levels of Ecological Organization
Lesson 4.1 Studying Ecology
Levels of Ecological Organization
Everything on Earth is connected, so how do ecologists study anything?
Ecology is the study of how organisms interact with each other and with their environments
Scientists study ecology at various levels of organization.

4. Levels of Ecological Organization
Individual
Ecology involves describing relationships between individual organisms and their environment.
Populations
Individual organisms are classified - species
Species = group of individuals that interbreed and produce fertile offspring
Members of a species that live in the same area at the same time = a population.

5. Levels of Ecological Organization
Communities
All of the populations in a particular area.
Ecology involves interactions among species.
Ecosystems
Include all the livings things and their physical environments within a particular area
Living and nonliving things.
Ecology involves studying the living and nonliving components of a system together.

6. Levels of Ecological Organization
Biosphere
Includes all parts of Earth that host life, with all of its organisms and environments.
Ecology involves how matter and energy cycle through the biosphere and influence organisms worldwide.

7. Biotic and Abiotic Factors
Lesson 4.1 Studying Ecology
Biotic and Abiotic Factors
Biotic factors: Parts of an ecosystem that are living or used to be living
Ex: living tree, dead tree
Abiotic factors: Parts of an ecosystem that have never been living
Ex: oxygen, sunlight

8. Habitat The specific environment in which an organism lives
Lesson 4.1 Studying Ecology
Habitat
The specific environment in which an organism lives
Habitats consist of biotic and abiotic elements.
Habitats provide an organism with resources—anything an organism needs to survive and reproduce, including food, shelter, and mates.

9. Lesson 4.2 Describing Populations
From 1900 to 2000, the white-tailed deer population of New York state grew from about 20,000 to more than 1 million. Densities of more than 100 deer per sq mi occur in some metropolitan areas.

10. Lesson 4.2 Describing Populations
Population Size
The number of individuals in a population at a given time
Sudden and dramatic decreases in population size can indicate an unhealthy population headed toward extinction.
When population size increases or remains steady, it is often a sign of a healthy population.

11. Determining Population Size
It is nearly impossible to count each individual in a population
Population is estimated using sampling techniques.
Count individuals in small sample area
Use that to estimate number of individuals in large overall area
Counting Laysan Albatross Nests

12. Population Density Measure of how crowded a population is
Lesson 4.2 Describing Populations
Population Density
Measure of how crowded a population is
Larger organisms generally have lower population densities.
Low population density: More space, resources; finding mates can be difficult
High population density: Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators
Northern pintail ducks

13. Population Distribution
Lesson 4.2 Describing Populations
Population Distribution
How organisms are arranged within an area:
Random distribution: Organisms arranged in no particular pattern, resource are spread out
Uniform distribution: Organisms evenly spaced; individuals hold territories/compete for space
Clumped distribution: Organisms grouped near resources; most common distribution in nature

14. Population Distribution

15. Lesson 4.2 Describing Populations
Age Structure
Age structure describe the relative number of organisms of each age group within population
Can be used to predict future population growth of a population
Young individuals who have not yet reached the age where they can reproduce are called pre-reproductive
Older individuals past the age of having offspring are called post-reproductive

16. Age Structure
Population with even age distribution will likely remain stable (births = deaths).
Population made up of mostly post-reproductive individuals will likely decline over time.
Population made up of mostly pre-reproductive individuals will likely increase over time.

17. Age Structure Diagram
Age 
How will each population change over time?

18. Lesson 4.3 Population Growth
From 1800 to today, the human population has grown from about 1 billion to more than 6.8 billion—an exponential rate of increase.

19. Lesson 4.3 Population Growth
Biotic Potential
An organism’s maximum ability to produce offspring in ideal conditions
Many factors influence biotic potential, including gestation time (time to “be born”) and generation time (span from time of organism’s birth until time it has its own offspring).
Organisms with high biotic potential can recover more quickly from population declines than organisms with low biotic potential.