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ECOSYSTEM BALANCE. Chapter 6 (pgs. 88-107) Mrs. Paul. 6.1 RELATIONSHIPS IN THE ECOSYSTEM. All species interact and a change in the relationships may change a population and thus the food web. Relationships: Predator/Prey Parasitism Symbiosis. Predators and Prey.
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ECOSYSTEM BALANCE Chapter 6 (pgs. 88-107) Mrs. Paul
6.1 RELATIONSHIPS IN THE ECOSYSTEM • All species interact and a change in the relationships may change a population and thus the food web. • Relationships: • Predator/Prey • Parasitism • Symbiosis
Predators: consumers that actively hunt other organisms. • Example: praying mantis (predator) eating a dragon fly (prey) • Prey: organisms that a predator feeds upon • Example: a snake (predator) eating a praying mantis (prey). • The size of both populations influence each other
Increases in the hare population increase the lynx population. • More prey (food) can support more predators. • A decrease in the hare population leads to a decrease in the lynx population.
Parasitism: relationship in which one organism feeds on the tissues or body fluids on another. • Host: the organism on which the parasite feeds. • Parasites are harmful and have the potential to kill their host. • Depends on the host for many functions. • Examples: fleas, ticks, lice, protists, tapeworms.
Symbiosis: relationship where two species live closely together. • Parasitism-one harmed/one benefits • Mutualism-both benefit • Commensalism-one benefit/one not affected
Commensalism: relationship where one species benefits and the other is neither helped nor harmed. • Examples: barnicles living on the skin of whale.
Mutualism: relationship where both species benefits. • Examples: ants and acacia trees, flowers and insects that pollinate them, yucca plant and the yucca moth.
Check for Understanding: • What processes link the sizes of predator and prey populations? • Why are herbivores not considered to be parasites? • How are the 3 types of symbiosis different? How are they similar?
Ecological Succession: gradual process of change and replacement of some or all of the species in a community. • May take hundreds or thousands of years. • Each new community makes it harder for the previous community to survive. • Two main types: • 1. Primary Succession • 2. Secondary Succession
Primary Succession: sequence of communities forming in an originally lifeless habitat. • Occurs in habitats without life. • Examples: cooled lava field, bare rock after retreating glacier.
Steps: Formation of soil from exposed rocks as lichen and weather break them down. -Lichen: fungus and alga living in a mutualistic relationship. -Pioneer community: first community to colonize new habitat. 2. Grasses and small plants begin to grow from seeds carried by wind and animals. 3. Growth of non-woody plants with deep roots (shrub community). 4. Growth of pine forest 5. Growth of hardwood forest. -Climax community: community that does not undergo further succession.
Secondary succession: succession that occurs where a community has been cleared by a disturbance that does not destroy the soil. • Examples: fires, storms, human disturbances. • Frequently disturbed habitats may never reach the climax community. • Example: grassland frequently burned by fires.
Steps: 1. Fast-growing grasses and non-woody plants. 2. Larger shrubs grow. 3. Pine Forest 4. Hardwood Forest
Aquatic Succession • Starts with a body of water that is low in nutrients. • Leads to a fertile meadow as the lake fills in with vegetation over time.
Island Succession • Populations of new organisms can adapt quickly to fill new niches or to form new species.
Check for Understanding: • How does primary succession differ from secondary succession? • What is a climax community? • Suppose humans put out all the fires in a large area of grassland over a period of 100 years. What would happen to the grassland community?
6.3 BALANCE IN THE ECOSYSTEM • If ecosystems are not balanced, they do not survive. • Disruptions are normal; they trigger change in the ecosystem. • Chaos Theory • Suggests that ecosystems may be sensitive to very small changes.
We divide the ecosystems on Earth into several categories. • Biome: major type of ecosystem with distinctive temperature, rainfall, and organisms. • Terrestrial (land) biomes • Type of biome depends on average temperature and amount of precipitation the area receives. • Aquatic (water) biomes • Determined by water depths, nutrients, and nearness to land.
8 Major Terrestrial Biomes: • 1. Desert • 2. Tundra • 3. Coniferous Forest • 4. Deciduous Forest • 5. Rain Forest • 6. Steppe • 7. Prairie • 8. Savanna