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Population Interactions. 8.11A describe producer/consumer, predator/prey, and parasite/host relationships as they occur in food webs within marine, freshwater, and terrestrial ecosystems.
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Population Interactions 8.11A describe producer/consumer, predator/prey, and parasite/host relationships as they occur in food webs within marine, freshwater, and terrestrial ecosystems 8.11B investigate how organisms and populations in an ecosystem depend on and may compete for biotic and abiotic factors such as quantity of light, water, range of temperatures, or soil composition
What forms an organism? *An organism is any living thing from bacteria to plants and animals.* An organism must be made of at least one cell.
What forms a population? *Populationsform when individuals of the same species share a habitat at the same time.* Habitat is where a population lives. A habitat must support life with food, water, and other resources.
What forms a community? --*Communities form when populations interact with one another.* Communities can have several different habitats, places where organisms live.
What forms an ecosystem? --*Any living and nonliving things that interact together form an ecosystem. * Ecosystems as small as a drop of pond water to as big as the entire Earth. *Living = biotic Nonliving = abiotic*
Example: PJHS Ecosystem PJHS 8th grade 7th grade administration administration students Students Ecosystem? Community? Population? Organism?
*Producers can make their own food and break down the food to get energy to stay alive.*
*Consumers cannot make their own energy (food) source. They eat or absorb their energy.* consumer energy
*Predation occurs when one organism eats all or part of another organism.* The “kill” is usually quick.
*Predation requires predator and prey.* • Predator lives. (+) • Prey dies or is partially torn apart. (-) • Biologists use + / - symbols to make it easier to remember predator-prey relationships. + because it gains, and – because it is harmed. • *Food chains and food webs represent predator-prey relationships.*
*Venus fly trap – Both Producer & Consumer* • The Venus fly trap is a plant (producer) which means that it makes it own food by photosynthesis. • The Venus fly trap is also a predator plant because its leaves can snap shut over another organism. Chemicals are released to dissolve the prey, and the plant absorbs the extra nutrients.
Who lives? • Predators that are better at hunting or gathering food are more likely to survive in their population. • Prey that are better at hiding or running away are more likely to survive in their population.
Let’s look at this food web representing a marine community. • Identify a producer organism. • Identify a consumer organism. • Identify a predator-prey relationship.
Parasitism (+ / -) • Parasitism is also a + / - relationship where the parasite gains while the host is harmed. • Parasites harm the host over a longer period of time. • Predators harm prey quickly. • Parasites often live in or on the host so often it is to their advantage to keep the host alive because the host if the parasite’s energy (food) source.
The tomato hornworm is covered in wasp cocoons. The wasp cocoons are a parasite. The cocoons feed away on the hornworm host. When the cocoons are ready to pupate and no longer need the hornworm host, the hornworm has been eaten away and dies.
Parasite: tapeworm Host: human • Human eats infected meat. Tapeworm grows inside the intestine with head buried into intestine lining. Parts of tapeworm break off to grow into more tapeworm. Tapeworm absorbs nutrients as human eats. Human becomes malnourished and eventually dies.
Most animals have parasite-host relationships, but most food webs and food chains only show predator-prey relationships. • Parasites affect food chains and food webs. Sun Producer Primary Consumer Secondary Consumer • Imagine that the primary consumer is the host of a parasite. • How does this affect the producer population? How does this affect the secondary consumer population?
Identify a producer. Identify a consumer. Identify one predator-prey relationship. What happens if the salamander population is affected by a parasite?
Answers… • Identify a producer. • Oak acorns, Pine • Identify a consumer. • Mouse, Snake, Salamander, Pine borer, Kinglet, Hawk • Identify one predator-prey relationship. • Snake/Mouse, Snake/Salamander, Salamander/Pine borer, Kinglet/Pine borer, Snake/Kinglet, Hawk/Mouse, Hawk/Kinglet • What happens if the salamander population is affected by a parasite? • Less food for the snake, increased pine borer population
Summary Part 1: Label each organism in the food web as follows— • Producers (P) • Consumers (C ) Part 2: Label each organism in the food web as follows— • Primary consumers (PC) • Secondary consumers (SC) • Tertiary consumers (TC) • Quaternary consumers (QC)
Abiotic and Biotic Factors in Ecosystems 8.11B investigate how organisms and populations in an ecosystem depend on and may compete for biotic and abiotic factors such as quantity of light, water, range of temperatures, or soil composition
What is an ecosystem? • An ecosystem consists of biotic and abiotic factors in a given area. • Abiotic factors are all the non-living components of an ecosystem. • What are examples of abiotic factors? • Biotic factorsare all the living components of an ecosystem. • What are examples of biotic factors?
Biotic factors • Archaebacteria • Bacteria • Fungus • Protist • Plant • Animal Biotic factors are the living organism, which we have classified into these six kingdoms.
How do abiotic factors affect biotic factors? Consider the effect of each on organisms. • Average temperature • Amount of rainfall • Amount of sunlight • Amount of freshwater
Competition • *Organisms compete with one another for resources to survive. • Organisms best adapted to the conditions of the environment are more likely to get the resources needed to stay alive.*
Relationships drive change in ecosystems. • Let’s consider a predator-prey relationship. Predators must eat prey to survive. Prey is a biotic resource that affects a predator population. If the graph to the left represents the cardinal population over a given period of time, infer what thepopulation of the cardinal’s prey will be like over the same period of time.
Predator-prey relationship The red line represents the prey population. Why do you think the predator population declined? What will happen to the predator population over time if the prey population continues to decrease?
Relationships drive change in ecosystems. • Planarians are aquatic organisms that respond to various abiotic factors. • What factors trigger the greatest response? • How do you think the response to light affects a planarian’s survival? What would happen to planarians if the environment changed so the light levels change?
Food webs • What abiotic factors would affect aquatic plants in this ecosystem? • Which two populations compete for aquatic plants as its energy source? • Insect populations are dependent upon what two populations for energy?
