2. Communities & Ecosystems Chapter 37

3. Energy Flow The Sun is the ultimate source of energy Most Producers (autotrophs) rely on sunlight to make their own food Consumers (heterotrophs) rely on other organisms to obtain food energy

4. Classifying Consumers Based on Diet (Trophic Levels) Producer (Autotroph) Herbivores = primary (1°) consumer 1 st order carnivore = secondary (2°) consumer 2 nd order carnivore = tertiary (3°) consumer 3 rd order carnivore = quaternary (4°) consumer 5°, 6° and son depending on the length of the food chain.

5. Feeding Relationships Food Chains – show the one-way flow of energy in an ecosystem. Food Webs – show a network of complex feeding interactions between many organisms found in one ecosystem Trophic Level – each step in a food chain or food web

6. Food Chains Note: The arrow always points to the organism who is eating

8. Energy Flow through an Ecosystem

9. Energy Loss in a Food Chain

10. 1.Why is only 2% of the original energy from the sun passed down from the diatoms to the zooplankton (1° consumer)? Where does the other 98% go? 2.Where does the energy escape between the 1° consumer and the 2° consumer? 3.Why is there such a difference between the energy lost between the producer and the 1° consumer and the 1° and the 2° consumer?

12. Biomagnification Problem After a tanker ship crashes in the arctic, a level of 1 mg of a toxin is found per 1000L of seawater. Consider the following:  1 small fish filters 1000L of water per week  1 big fish eats 12 small fish per week  1 seal eats 24 big fish per week  1 polar bear eats 3 seals per week

13. 1. How many small fish are needed to the food chain? (i.e., to feed one bear) 2.How much of the toxin would the polar bear accumulate after 3 weeks? 3.Create a flow chart showing how much toxin would be accumulated per animal at each link in the food chain. 4.If 150 mg of this toxin will kill anything, where would the chain stop? 5.How many big fish would the bear have to eat to accumulate the same amount of toxin as in Q 2?

14. Food Chains & Webs Food chains and webs only show which organisms are found at each link in the chain/web. Food chains/webs do not show the make up of an ecosystem in terms of how many organisms are found at each level.

15. Number Pyramids Show the relative number of individuals at each tropic level.

16. Biomass Pyramids Represents the amount of organic matter at each trophic level.

17. Energy Pyramid  Shows the relative amount of energy available at each trophic level.

20. Which Pyramid? Which is the best pyramid to use? Show an example of a feeding chain that does not keep it’s pyramid form.

22. Community Interactions An ECOSYSTEM consists of both biotic and abiotic factors A COMMUNITY is made up of all the biotic factors in an ecosystem and could include many different populations Within a community, living things interact.

23. Types of Interactions Competition – for food, living space, water and shelter Predation – a relationship where one organism benefits and the other dies Mutalism –both organisms benefit Commensalism – a one-sided symbiotic relationship where only one organism benefits and the other is not affected Parasitism – one organism benefits while the other suffers without dying

24. Interspecific Competition Competition among two different species for the same resources, i.e. they occupy the same niche Can lead to: 1.Competitive Exclusion Principle – where the less competitive species is driven to extinction 2.Resourse partitioning – where one species evolves through natural selection to occupy a slightly different niche

25. Classic Test for the Competitive Exclusion Principle

26. Resource Partitioning

27. Remora attaches itself to a shark Crinoid perched on a volcano sponge Commensalism Orchid growing on a tree

28. MUTUALISM

29. Mutualism

31. Gobi and Wrasse Mutualism

32. Cleaner Shrimp & Goatfish - Mutualism

33. PARASITISM

34. Trichina Infection Parasitism

35. Trichina infection in man

36. Tapeworm Infection

37. Tapeworm - Scolex

40. Bladderworms in the Brain

41. Nutrient Cycling

46. Loss of nitrate from a deforested watershed

48. Natural Succession Natural Succession is a predictable sequence of change in an ecosystem’s plant life. Ex. White birch trees “nurse” young spruces by providing shade for them to grow in. BUT once the spruce grow they begin to cast shade upon the birch which need sunlight. Therefore, a forest of birch gets replaced (OR SUCCEEDED) by a forest of spruce.

49. Primary Succession The sequence of changes in plant life that begins with bare rock where there was previously no life. Starts with soil formation Many 1000s of years

50. Bare Rock  Lichen-covered rock  Moss-covered rocks & stones  Grass plant growth & soil development  Shrub growth  Intermediate-stage deciduous forest  Climax community coniferous forest Stages of natural succession are classified according to the DOMINANT autotrophs of the ecosystem

51. Secondary Succession The sequence of changes in plant life after a disruptive event such as fire or logging to a climax community. ~200 years