1. Big Idea 17: Interdependence
Description   A. Plants and animals, including humans, interact with and depend upon each other and their environment to satisfy their basic needs.
B. Both human activities and natural events can have major impacts on the environment.
C. Energy flows from the sun through producers to consumers.

2. Benchmark Number& Descriptor
SC.7.L.17.1
Explain and illustrate the roles of and relationships among producers, consumers, and decomposers in the process of energy transfer in a food web.
SC.7.L.17.2
Compare and contrast the relationships among organisms such as mutualism, predation, parasitism, competition, and commensalism.
SC.7.L.17.3
Describe and investigate various limiting factors in the local ecosystem and their impact on native populations, including food, shelter, water, space, disease, parasitism, predation, and nesting sites.

3. Ecosystems include…
Organisms that live in a particular area
physical surroundings
Organisms interacting with each other
by sharing and competing for resources
Organisms interacting with their physical environment
Bottom Line: Ecosystems can be found wherever organisms are living and interacting!

4. ECOLOGICAL RELATIONSHIPS
HABITAT & NICHE
ENVIRONMENTAL FACTORS
Habitat – An organism’s habitat is where it lives in an ecosystem.
Niche – a certain role that each population has in its environment (ex. Both eagles and owls feed on mice, but owls hunt at night while eagles hunt during the day.)
In a healthy ecosystem, populations are interdependent – they depend on each other for survival!
The environment determines the type of ecosystem that will develop in an area.
Factors include:
Soil conditions
Temperature
Rainfall
Plant Life
Amount of Food

5. KNOWLEDGE CHECK
A single organism in an environment is called an _______.
In a healthy ecosystem, each population contributes to the ______ of the other populations.
The amount of food is a ________ that affects population density.
A ______ is a place where a population lives in an ecosystem.
A population has a role or _______ in its environment.
The sizes of animal populations are determined by the kinds and numbers of __________ in an ecosystem.
Word Bank:
niche plants
individual habitat
limiting factor survival

6. KNOWLEDGE CHECK
A single organism in an environment is called an individual.
In a healthy ecosystem, each population contributes to the survival of the other populations.
The amount of food is a limiting factor that affects population density.
A habitat is a place where a population lives in an ecosystem.
A population has a role or niche in its environment.
The sizes of animal populations are determined by the kinds and numbers of plants in an ecosystem.

7. How Energy Is Transferred in an Ecosystem
The sun provides the energy for almost every ecosystem on Earth. Producers use the sunlight to make food they need from carbon dioxide and water (ex. plants).
Consumers – all the animals in a community (ex. all the animals that are eating)

8. Food Chains
Food chains show how consumers, producers, and decomposers are related for survival.
Begins with producers (usually plants)
Next level contains herbivores – animals that eat only plants.
They are eaten by the next level of animals on the food chain – the carnivores (meat eaters).
The chain continues with more levels of carnivores that eat one another.
The chain ends with decomposers such as bacteria which breaks down the tissues of dead organisms. Whatever is left over returns to the soil and helps start the cycle over again by giving nutrients to the producers!

9. EXAMPLES of PRODUCERS AND CONSUMERS
Both land and marine

10. EXAMPLES of FOOD CHAIN RELATIONSHIPS
GRASSES
(producers)
Lions
Predator
Insects, Birds, Hyenas, Worms
Secondary and Tertiary consumers
Carnivores, Omnivores
Zebras and Gazelles
Primary Consumers Herbivores
Energy from the grass is both used and
stored by the animals who eat the grass
directly and by those who eat those animals.

11. KNOWLEDGE CHECK 1. Where are ecosystems found?
2. What are the three links in the food chain?
3. Give an example of each link in the food chain.

12. KNOWLEDGE CHECK 1. Where are ecosystems found?
Ecosystems can be found wherever organisms are living and interacting!
2. What are the three links in the food chain?
Producer, Consumer, Decomposer
3. Give an example of each link in the food chain.
Producer = Plants
Consumer = Bear
Decomposer = Bacterial

13. ECOLOGICAL RELATIONSHIPS
COMPETITION
Resources in ecosystems may be limiting; therefore, competition for these resources may occur.
Resources under competition may include food, water, sunlight, or shelter
The more needs that are in common, the more intense the competition.
If an organism competes successfully for resources, it is more likely to survive and reproduce!
This is why there are PREDATORS and PREY!

14. ECOLOGICAL RELATIONSHIPS
Symbiosis: A close relationship between organisms of different species
4 types of symbiosis:
Commensalism
Mutualism
Parasitism
Mimicry

15. ECOLOGICAL RELATIONSHIPS
Parasitic Isopod on fish
Commensalism- A relationship in which one organism benefits and the other is not affected
Mutualism – A relationship in which both organisms benefit from each other
Parasitism – A relationship in which one organism benefits and the other is harmed
Mimicry – When species mimic colors, patterns, or behavior of another species in order to get closer to unsuspecting prey or to gain protection by imitating a predator
Imperial shrimp hitching a ride on a sea-cucumber
Clownfish in host sea anemone
Two of these are Bumblebees(with stingers) and two are Robber Flies (which also make a sound similar to a bee).

16. KNOWLEDGE CHECK
Living on the Serengeti Plain are herds of lions, zebras, hyenas, birds, ticks, and fleas. Using this information, list the ecological relationships in terms of competition and symbiosis.

17. KNOWLEDGE CHECK
Living on the Serengeti Plain are herds of lions, zebras, hyenas, birds, ticks, and fleas. Using this information, list the ecological relationships in terms of competition and symbiosis.
SYMBIOSIS COMPETITION
Mutualism: Zebra and Bird Zebra and Hyena
Commensalism: Lion and Hyena (Both eat grass).
Parasitism: Flea and Lion

18. LIMITING FACTORS
Limiting factors are things that prevent a population from growing any larger.
If any of the limiting factors change, animal and plant populations change, too.
Limiting factors include:
Water
Food
Shelter
Space
Predation
Disease

19. Limiting Factors FOOD/WATER SHELTER/SPACE
If there is limited food for a population, the species will not survive.
Lack of food or water can create competition among populations and species.
Without proper nutrition, species cannot thrive and survive.
SHELTER: is a prime factor. Without proper shelter, predators can diminish a population quickly.
SPACE: Humans can impact animal and plant populations. When humans develop land for houses and buildings, they cut down trees and change animal and plant habitats.

20. Limiting Factors
Limiting factors are very closely tied to carrying capacity. Many kinds of animals can increase in numbers very quickly and may temporarily exceed the carrying capacity of their habitat.
This results in stress, starvation, disease, predation, and parasites, poor reproductive success and damage to the habitat.
For example, multiplying muskrats can very quickly eat all the vegetation in a marsh. With the vegetation gone, food becomes the limiting factor, and the muskrats may starve or move to another area. The marsh now has a reduced carrying capacity for muskrats until the vegetation grows back again.

21. KNOWLEDGE CHECK
Living on the Serengeti Plain are herds of lions, zebras, hyenas, birds, ticks, and fleas. Using this information, what is/are the limiting factor(s) of this ecosystem?

22. KNOWLEDGE CHECK
Living on the Serengeti Plain are herds of lions, zebras, hyenas, birds, ticks, and fleas. Using this information, what is/are the limiting factor(s) of this ecosystem?
Grass and water. Without these, the bottom of the food pyramid would disappear, creating a chain reaction to the top.