1. Chapter 18 – Introduction to Ecology
Section 1: Introduction to Ecology

2. Ecology
Ecology is the study of the interactions between organisms and the biotic and abiotic components of their environment
Biotic = living
Abiotic = nonliving

3. Today’s Environment The Exploding Human Population
The world’s human population has tripled from 2 billion people in to 6 billion people in 1999
Causes severe crowding
Requires an increasing amount of food, energy and space for disposing waste

4. Today’s Environment The 6th Mass Extinction
Species are disappearing faster than at any other time since the last mass extinction
About 20% of the species of birds have become extinct in the last years
Caused by:
Habitat destruction
Over-hunting
New diseases and predators being introduced to non-native areas

5. Today’s Environment The Thinning Ozone Layer
The ozone layer protects Earth’s living organisms by absorbing UV radiation from the sun
Industrial chemicals called chlorofluorocarbons (CFCs) react with the ozone and are destroying the ozone later
In 1992 a ban was established on using CFCs and related chemicals
In 1996, the ozone level over Antarctica was about 50% of the maximum density
This allows in extra UV radiation that can lead to sunburn and skin cancer

6. Today’s Environment Climatic Changes
Greenhouse Effect: the ability of carbon dioxide and water vapor to trap the reflected heat from the sun and direct it back towards the Earth
Protects the Earth from the deep-freeze of space
Human use of fossil fuels has increased the amount of carbon dioxide in the atmosphere by 25% in the last 100 years
The increase of greenhouse gases are trapping excess heat in our atmosphere, causing global temperatures to rise
Scientists warn that if the problem is not corrected in the next 10 years, the condition of our Earth will not be able to be reversed

7. A Key Theme in Ecology No single organism is isolated!!
The interconnectedness or interdependence of all organisms is central to the study of ecology
The survival of organisms depends on their interactions with their surrounding environment
Ex: Humans cannot live without the plants that produce food and oxygen

8. Levels of Organization

9. The Biosphere
Biosphere: the broadest and most inclusive level of organization
The Earth and its atmosphere make up our biosphere
Extends from 8 to 10 km (5-6 miles) above the Earth’s surface to the deepest parts of the ocean

10. Ecosystems
The biosphere is comprised of smaller units called ecosystems
Includes all of the organisms and the abiotic environment found in a specific place
Ex: Pond Ecosystem
Abiotic components: water temperature, amount of dissolved oxygen and carbon dioxide, the pH level
Biotic components: insects, fish, algae, aquatic plants, turtles

11. Ecosystem
Chapter 18

12. Communities, Populations and Organisms
A community is all of the interacting organisms living in an area
Ex: All of the fish, turtles, insects, plants and algae make up the community of a pond
A population includes all of the members of a species that live in one place at one time
Ex: All of the humans in Vernon Hills
An organism is a single, living thing.
Ecologists study organisms for their adaptations that allow them to overcome the challenges of their environment

13. Chapter 18
Community

14. There are none! Brain Break
Try to count the number of black dots on the image below...
There are none!

15. Chapter 18 – Introduction to Ecology
Section 2: Ecology of Organisms

16. Biotic and Abiotic Factors
Environmental factors found in an organisms habitat are broken into two classes:
Biotic = living components of the environment
Abiotic = nonliving components of the environment
Includes:
Temperature
Humidity pH
Salinity
Oxygen concentration
Amount of sunlight
Availability of nitrogen
Precipitation

17. Biotic and Abiotic Factors
Visual

18. The Changing Environment
Abiotic factors are NOT constant
Ex: Temperature
Varies from hour to hour, day to day, season to season, and year to year
Varies from place to place:
Phoenix will be hotter than Chicago
Can vary within a habitat
Different in temperature between being in the shade of a tree vs. out in direct sunlight

19. Responses to a Changing Environment
Organisms are adapted to function within a specific range of an abiotic factor
Ex: Temperature
All organisms have a range of temperature in which they can function
To determine the range in which an organism can live, you can measure how efficiently it performs at specific temperatures
A tolerance curve is a graph of performance vs. values of an environmental variable
Performance is usually reduced when the values are outside of the optimal range
Organisms cannot survive in areas where they are exposed to conditions that fall outside of their tolerance range

20. Tolerance Curve Zones of Physiological Intolerance (no performance)
Zones of physiological stress (reduced performance)
Swimming Speed
Temperature

21. Acclimation
Acclimation is the process by which organisms can adjust their tolerance to abiotic factors
Ex: Going to the mountains
If you spend a few weeks in the mountains, your body will acclimate to the lower oxygen levels by producing more red blood cells in your body
This will allow your blood to carry more oxygen
Acclimation IS NOT adaptation!!
Adaptation is a genetic change in a species that occurs over many generations – acclimation occurs within the lifetime of a species

22. Control of Internal Conditions
The abiotic factors within an environment can fluctuate
Two ways to deal with the changes:
Conformers: do not regulate internal conditions; they change as their environment changes
Ex: Desert lizards’ rises and falls with the temperature of their environment
Regulators: use energy to control some of their internal conditions
Ex: humans maintain a constant internal body temperature

23. Escape from Unsuitable Conditions
Organisms have developed strategies for surviving unfavorable environmental conditions:
Dormancy: a state of reduced activity during which an organism’s metabolism slows down
Ex: Reptiles and amphibians “hide” underground and become dormant during the winter to survive the cold temperatures
Migration: when organisms move to a more favorable environment
Ex: Seasonal movements of birds

24. Resources
Resources: the energy and materials that an organism needs to survive
Ex: Food, water, shelter and sunlight
The resources essential for survival vary between different species
Ex: The resources plants require are different from those humans need

25. The Niche
A specie’s niche is the role an organism plays in its environment
Includes:
Range of conditions the organism can tolerate
Methods by which it obtains resources
Interactions with its environment such as reproduction
A fundamental niche is the range of conditions that a species can potentially tolerate and the range of resources it can potentially use
A realized niche is the range of resources an organism actually uses

26. The Niche
Visual

27. Niche Differences Generalists are species with broad niches
Can tolerate a range of conditions and use a variety of resources
Ex: Virginia opossum  found all over the US and can eat a wide range of food
Specialists are species that have narrow niches
Ex: koalas  only feed on leaves from a few species of eucalyptus trees