1. There are levels of organization in an ecosystem:
Intro to Ecology
Ecology is the branch of biology that deals with the interactions between organisms and the relationship between organisms and the environment.
No organism exists in nature alone, apart from it’s environment.
There are levels of organization in an ecosystem:
Population
Community
Ecosystem
Biosphere
Mrs. Degl

2. Population – all members of a particular species make up a population
Population – all members of a particular species make up a population. An example is how all of the water lilies in a pond are one population and all of the gold fish in a pond are another separate population.
Community - all of the populations interacting together make up community. All of the plants, animals, and microorganisims in a pond make up a community.
Mrs. Degl

3. Ecosystem – includes all of the members of a community along with the physical environment in which they live. The living and non-living parts of an ecosystem function together. An ecosystem is the structural and functional unit studied in Ecology.
Biosphere – the portion of the Earth in which all living things exist. Water, soil, and air are included with the living things in the biosphere.
Mrs. Degl

4. What makes an ecosystem?
The ecosystem involves interactions between living and nonliving things. Two requirements must be met for a stable ecosystem to exist:
There must be a constant supply of energy (sunlight for photosynthesis). There must also be living organisms that can incorporate the energy into organic compounds (food). These are autotrophs.
There must be a recycling of materials between living organisms and the non-living materials (environment).
Mrs. Degl

5. An ecosystem had both abiotic (non-living) and biotic (living) parts.
The abiotic factors of an ecosystem include the physical and chemical factors that affect the capacity of an organism to live and reproduce. These factors are:
1. Intensity and duration of light
2. Temperature range
3. Amount of water
4. Type of soil
5. Availability of inorganic substances (minerals) and gases (O2, CO2, N)
6. pH of soil/water
Mrs. Degl

6. Limiting Factors
Abiotic factors vary between environments. Because the abiotic factors in an environment determine which plants/animals live there, they are called limiting factors.
For example, the amount of water in a desert limits the kinds of plants and animals that can live there.
Mrs. Degl

7. Biotic Factors
Biotic factors include all of the living things that directly or indirectly affect the environment.
Thus the organisms, their presence and parts, interaction, and wastes all act as biotic factors
These interactions include:
1. Nutritional relationships
2. Symbiotic relationships
Mrs. Degl

8. Nutritional Relationships
Involves the transfer of nutrients from one organism to another within an ecosystem.
In terms of nutrition, organisms are either autotrophs or heterotrophs.
Autotrophs are organisims that can use energy from the environment to make their own food from inorganic compounds.
Heterotrophs cannot make their own food and must obtain nutrients from other organisims.
Mrs. Degl

9. Heterotrophs can be classified into one of the following:
Saprophytes are organisms that obtain nutrients from dead organisms. Bacteria and fungi are examples.
Herbivores are animals that feed exclusively on plants.
Carnivores are animals that consume other animals.
Predators kill and eat their prey.
Scavengers feed on the remains of animals that other animals killed, not them.
4. Omnivores are animals that consume both plant and animal remains.
Mrs. Degl

10. Symbiotic Relationships
Different organisms may live together in a close association
This is known as symbiosis
There are three types:
1. Commensalism 2. Mutualism 3.Parasitism
KEY:
+ = benefits
- = harmed
o = not affected
Mrs. Degl

11. Ex: barnacles on a whale
Commensalism
(+ , o)
In this relationship, one organism benefits and the other is not affected
Ex: barnacles on a whale
Mrs. Degl

12. Mutualism
(+ , +)
In this relationship both organisms benefit from each other
Ex: protozoan living in the digestive tract of termites
Wood eaten by termites is digested by the protozoan. The nutrients released supply both organisms
Mrs. Degl

13. Parasitism
(+ , - )
In this relationship, the parasite benefits at the expense of the host
Ex:
athlete’s foot fungus on humans
tapeworm and heartworm in dogs
Mrs. Degl

14. Food Chains Producers: Autotrophs that use photosynthesis to make food
Consumers: All heterotrophic organisms that obtain energy from the food that they eat.
Primary Consumers (Herbivores): feed on green plants and algae
Secondary Consumers (Carnivores): feed on primary consumers
Omnivores eat plants and animals. Humans are omnivores.
Decomposers: (saprophytes) Break down the remains of dead organisms and organic wastes. They return the nutrients to the environment, where they can be recycled and used again. Bacteria and fungi are examples. The recycling is essential to an environment so dead remains do not accumulate.
Food Chains
Mrs. Degl

15. FOOD
WEB
Mrs. Degl

16. Food Chains vs. Food Web
A food chain is the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten.
Green plants obtain energy from Sunlight (photosynthesis) and all other organisms obtain energy from the breakdown of food.
In real life most organisms eat more than one organism and are eaten by more than one organism, so food chains are interconnected forming food webs.
Food webs have the same levels of organisms but the flow of energy and materials is more complex.
Mrs. Degl

17. Food Chains vs. Food Web
A food chain is the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten.
Green plants obtain energy from Sunlight (photosynthesis) and all other organisms obtain energy from the breakdown of food.
In real life most organisms eat more than one organism and are eaten by more than one organism, so food chains are interconnected forming food webs.
Food webs have the same levels of organisms but the flow of energy and materials is more complex.
Mrs. Degl

18. Pyramid of Energy
The greatest amount of energy in a community is present in the producer level.
Only a small portion of this energy is passed on to primary consumers, and only a smaller portion is passed on to secondary consumers.
An energy pyramid can be used to show the loss of usable energy at each feeding (trophic) level.
Mrs. Degl

19. Pyramid of Biomass
In general, the decrease in available energy at each higher feeding means that less organic matter or biomass can be supported at each higher level.
Thus, the total mass of producers in an ecosystem is greater than the total mass of primary consumers, and the total mass of primary consumers is greater than the total mass of secondary consumers and so on.
A biomass pyramid can be used to show this decrease in biomass at each higher feeding level.
Mrs. Degl

20. Carrying Capacity
In every ecosystem on Earth, there are limited amounts of available resources. These include food, water, energy, minerals, and space.
The amount of resources available limits the number of organisms that an ecosystem can support.
The maximum number of organisms of a particular type that can be supported in an area is known as the carrying capacity.
If the population increases significantly above it’s carrying capacity, many individuals die off because of insufficient resources.
Mrs. Degl

21. Competition
Different species living in the same environment, or habitat, may require the same resources. When the resources are limited, competition occurs among the species.
Competition- is the struggle between different species for the same limited resources. The more similar the needs of the species, the more intense the competition.
Each species occupies a niche in the community. A niche is the role the species plays, and includes the type of food it eats, where it lives, where it reproduces, and its relationships with other species.
When two different species compete for the same niche in a community, the weaker species is usually eliminated establishing one species per niche in a community.
Mrs. Degl