1. 5.1: Communities Topic 5: Ecology & Evolution Miss Friedman

2. 5.1.1: Definitions Ecology The study of the relationship between living organisms and between those organisms and their environment Ecosystem A community and its abiotic environment Population A group of organisms of the same species who live in the same area at the same time

3. 5.1.1: Definitions Community Populations of different species in the same area which are interacting Species A group of organisms which can interbreed and produce fertile offspring Habitat Location within which a species normally lives

4. 5.1.2: Autotrophs & heterotrophs AutotrophProducer An organism that synthesises its organic molecules from simple inorganic molecules Heterotrop h consumer Obtains organic molecules from other organisms

5. 5.1.3: Consumers, detritivores, saprophytes Consumers An organism that ingests other organic matter that is living or recently dead Detritivores An organism that ingests non-living organic matter Saprophytes An organism that lives on or in non-living organic matter, secreting digestive enzymes into and absorbing the products of digestion

6. 5.1.4: Food chains ► Food chains show a simple linear flow of “who eats who” ► Therefore shows the energy flowing through the links in the chain Questions to consider! How is energy lost in the chain? Why are big, dangerous predators so rare?

8. 5.1.5: Food webs ► A diagram that shows how food chains are linked together into more complex feeding relationships Advantages over food chain o Shows much more complex interactions between species within a community/ecosystem o More than one producer supports a community o A single producer is a food source for many primary consumers o A consumer might have a number of different food sources on the same/different trophic levels o A consumer can be an omnivore, feeding as a primary consumer but also as a consumer at higher tropic levels

10. 5.1.6: Trophic level ► The tropic level of an organism defines the feeding relationship of that organism to other organisms in a food web AutotraphProducer Tropic level 1 Hetertroph Primary consumer Tropic level 2 Hetertroph Secondary consumer Trophic level 3 heterotroph Tertiary consumer Trophic level 4

11. 5.1.7: Determining tropic levels in food chains/webs ► Assign tropic levels to the food web on the right!

12. 5.1.8: Constructing a food web ► Producers are usually shown at the bottom ► Use full name of organisms ► Arrows show the movement of matter & energy

13. 5.1.9:Light & food chains ► Sunlight is the source of energy for most communities, both aquatic and terrestrial ► Very few communities deep in the ocean use geothermal energy

14. 5.1.10: Energy flow in Food chain ► a) Not all solar energy will come into contact with chlorophyll and will therefore not be trapped in the synthesis of organic compounds ► b) Photosynthesis ► c) Consumers feeding and passing on energy in the food ► d) Loss of energy as heat from respiration ► e) death and the consumption of dead organisms by detritivores. Or as food not assimilated because of incomplete digestion. Energy Loss ► loss of energy in undigested food which will then be used by saprophytes/ decomposers ► loss of heat energy in the reactions of respiration ► ultimately all energy will be lost has heat

15. 5.1.11: Efficiency of energy transformations ► When energy is changed from one form into another, it is never 100% efficient ► Approximately only 10-20% of the energy on one trophic level will be assimilated at the next higher trophic level

16. 5.1.12: Shape of energy pyramids ► A pyramid of energy is a graphical representation of the amount of energy of each trophic level in a food chain ► The units are kJ/m 2 /yr ► The narrowing shape illustrates the gradual loss of energy processing along the links of a food chain to higher trophic levels

17. 5.1.13: Energy and matter in ecosystems ► Energy is NOT recycled through the ecosystem ► Energy is constantly received from the sun and constantly radiates out in the form of light & heat ► Matter IS recycled ► The process of recycling nutrients requires energy

18. 5.1.14: Decomposers ► Two main groups are detritivores (e.g. earthworms, dung beetles) and saprotrophs (e.g. fungi, bacteria) ► Decomposition is a complex process and serves many functions; formation of soil, recycling of nutrients, reduction of high energy carbon compounds ► Organic molecules are oxidized to release nitrogen in the form of nitrate, nitrite, and ammonia ► Oxidation of organic compounds provides energy for saprophyte but returns matter to abiotic environment