Unit 3 - Chapter 5, Part 2

1. Unit 3 - Chapter 5, Part 2 Interactions: Environments and Organisms Edited by David Rude

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4. Interactions: Environments and Organisms

5. Kinds of Organism Interactions • Predation • Interaction where one animal kills/eats another. • Predator • The organism that eats another. • Prey • Animal that is eaten • adaptation - higher reproduction rate.

6. Competition • Competition • Interaction where two organisms strive to obtain the same limited resource. • Intraspecific competition • Competition between members of same species. • Interspecific competition • Competition between members of different species.

7. Competition • Competitive exclusion principle • No two species can occupy • The same ecological niche* • In the same place • At the same time. • Less-fit species must evolve into a slightly different niche. • NOTE* Niche– an organism’s profession • The functional role the organism has in its surroundings.

8. Symbiotic Relationships • Symbiosis • A close, long-lasting, physical relationship between two different species. • At least one species derives benefit from the interaction. • There are three categories of symbiotic relationships: • Parasitism • Commensalism • Mutualism

9. Symbiotic Relationships • Parasitism • Relationship where one organism (parasite) lives in or on another organism (host), from which it derives nourishment. • Ectoparasites live on the host’s surface. • Fleas, lice, molds, mildews • Endoparasites live inside the body of the host. • Tapeworms, malaria parasites, bacteria, fungi

10. Symbiotic Relationships Examples of symbiotic relationships

11. Symbiotic Relationships Examples of symbiotic relationships

12. Symbiotic Relationships • Commensalism • Relationship where one organism benefits while the other is not affected. • Remoras and sharks

13. Symbiotic Relationships • Mutualism • Relationship where both species benefit. • The relationship is obligatory in many cases • Neither can exist without the other.

14. Symbiotic Relationships • Examples of Mutualism • Certain fungi and plant roots • Oxpecker and impala

15. Human Niche • Varies in different parts of the world • Predator, Herbivore, Scavenger • Commensalism • Many organisms use our homes as places to live without affecting us • Parasitism • Blood drawn from cows and mixed with milk • Mutualism • Domestic animals & pets

16. Community and Ecosystem Interactions • Community • All interacting species of organisms in an area. • Ecosystem • A defined space in which interactions take place between a community • Includes: • All its complex interrelationships • The physical environment.

17. Major Roles of Organisms in Ecosystems • Three broad categories • 1st – Producers: • Use sources of energy to make complex organic molecules from simple inorganic substances in their environment. • Usually the Sun • Can be chemical • Plants, algae, phytoplankton

18. Major Roles of Organisms in Ecosystems • 2nd – Consumers: • Require organic matter as a source of food • Use for energy and organic molecules necessary for growth and survival • Consumers divided into categories based • The things they eat • The way they obtain food

19. Major Roles of Organisms in Ecosystems • Three consumer categories: • Primary consumers • Herbivores - eat plants as a source of food. • Secondary consumers • Carnivores - animals that eat other animals. • Omnivores • Consume both plants and animals.

20. Major Roles of Organisms in Ecosystems • 3rd – Decomposers: • Use nonliving organic matter as a source of energy and raw materials to build their bodies. • Many small animals • Bacteria • Fungi

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22. Keystone Species • Keystone species • Plays a critical role in the maintenance of specific ecosystems.

23. Energy Flow Through Ecosystems • Trophic levels • Each step in the flow of energy through an ecosystem • Second law of thermodynamics • Whenever energy is converted from one form to another, some of the energy is converted to a non-useful form (typically, low-quality heat) • As energy moves from one trophic level to the next • 90 % of useful energy is lost as heat (second law of thermodynamics).

24. Energy Flow Through Ecosystems • Biomass • Weight of living material • Difficult to measure the amount of energy contained in each trophic level • Use biomass as a rough measure

25. Energy Flow Through Ecosystems Categories of organisms within an ecosystem.

26. Figure 05_26

27. Food Chains and Food Webs • Food chain • A series of organisms occupying different trophic levels • A result of one organism consuming another • Some chains rely on detritus • Particles of fecal waste or decomposing plans/animals

28. Food Chains and Food Webs • Food web • A series of multiple, overlapping food chains. • Single predator can have multiple prey species at the same time.

29. Food chain Food web Food Chains and Food Webs

30. Nutrient Cycles in Ecosystems—Biogeochemical Cycles • Organisms are composed of molecules and atoms • Cycled between living and non-living portions of an ecosystem. • These nutrient cycles are called Biogeochemical cycles • Bio – living organisms • Geo – physical environment • Chemical – specific atoms and molecules

31. Carbon Cycle • Carbon and oxygen combine to form carbon dioxide • Producers (Plants) use carbon dioxide during photosynthesis to produce sugars • Use sunlight to combine CO2 and H2O into sugar • Use sugars for plant growth

32. Carbon Cycle • Consumers (Herbivores & Carnivores) • Eat plants or other animals that eat plants • Break down the complex organic molecules into simpler molecular building blocks • Incorporate those molecules into their structure. • Respiration breaks down organic molecules into • CO2 and H2O • Releases compounds back into the atmosphere.

33. Carbon Cycle • Decomposers feed on organic molecules of dead • Produce CO2 through respiration • Recycles naturally occurring organic molecules.

34. Carbon Cycle • Burning fossil fuels • Takes carbon atoms that were removed temporarily from the active, short-term carbon cycle • Reintroduces them into the active cycle

35. Carbon Cycle Carbon cycle

36. Nitrogen Cycle • The cycling of nitrogen atoms between abiotic and biotic ecosystem components. • Producers are unable to use atmospheric N. • Must get nitrate (–NO3)or ammonia (NH3.)

37. Nitrogen Cycle • Nitrogen-fixing bacteria convert nitrogen gas N2 into ammonia. • Plants construct organic molecules. • Eaten by animals. • Decomposers also break down nitrogen-containing molecules, releasing ammonia.

38. Nitrogen Cycle • Nitrifying bacteria • Convert ammonia to nitrite • Can be converted to nitrate. • Denitrifying bacteria • Able (under anaerobic conditions) to covert nitrite to nitrogen gas (N2) • Ultimately released into the atmosphere.

39. Nitrogen Cycle Nitrogen cycle

40. Phosphorus Cycle • Phosphorus is not present in the atmosphere as a gas. • The ultimate source is rock. • Phosphorus compounds are released by erosion • Become dissolved in water. • Plants use phosphorus to construct necessary molecules. • DNA, cell membranes, ATP

41. Phosphorus Cycle • Animals gain phosphorus when they consume plants or other animals. • Decomposers recycle phosphorus compounds back into the soil.

42. Phosphorus Cycle Phosphorus cycle

43. Human Impact on Nutrient Cycles • Burning of fossil fuels • Releases large amounts of carbon dioxide into atmosphere. • Increases amount of nitrogen available to plants. • Converting forests (long-term carbon storage) to agricultural land (short-term carbon storage) • Increased amount of carbon dioxide in atmosphere.

44. Human Impact on Nutrient Cycles • Nitrogen or phosphorus is applied as fertilizer • When too much is applied • Applied at the wrong time • Much is carried into aquatic ecosystems. • Increases the growth rate of bacteria, algae, and aquatic plants. • Toxic algae can kill fish and poison humans. • Lowers oxygen concentrations creating “dead zones.”

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