Chapter 7.2 Ecological Interactions

1. Chapter 7.2Ecological Interactions

2. Learning Objectives • By the end of the lesson, you should be able to: • show an understanding of the interrelationship among the various organisms in a community • describe the interactions between organisms such as: mutualism, commensalism, parasitism, herbivory, predation and competition.

3. Ecological Interactions • Organisms interact in many way. • We may classify these interactions based on the following chart: • Only organism A benefit from the interaction between them; B is harmed in some way or may even die from the relationship. • Examples: • Cheetah and Thompson’s gazelles + 0 - + + - • Both organisms suffer some form of disadvantage. • Examples: • Plants growing in the undergrowth. Commensalism Competition Mutualism - Exploitative Relationships (Parasitism, Herbivory, Predation) + • Both organisms A and B benefit from the interaction between them. • Examples: • Clown fish and Sea anemone • Fig wasps and fig trees SYMBIOSIS • Only organism A benefit from the interaction between them; B receives no benefit and is not disadvantaged in any way. • Examples: • Orchids and ferns growing on tree trunks.

4. Examples of Mutualism Clownfish & Sea anemone Ants & Aphids Cleaner shrimps & Eel Egyptian plover & Crocodile

5. Examples of Commensalism Epiphytes & Raintree Cattle Egret & Cattle Barnacles & Scallop Remora & Shark

6. Predation, Herbivory, Parasitism Predation Cheetah & Thompson Gazelle Herbivory Zebra & Grass Predation & Parasitism Mosquito, Plasmodium (Malaria parasite) & Man Parasitism Tree-Ear Fungus & Tree

7. Predation, Herbivory, Parasitism Interspecific Competition Great Blue Heron, Great Egret and Snowy Egret hunting fish Interspecific Competition Lion & Hyena Intraspecific Competition Reindeers competing for mate Inter and Intraspecific Competition Trees competing for light

8. Chapter 7.3Energy & Productivity

9. Learning Objectives • By the end of the lesson, you should be able to: • state that the Sun is the principal source of energy input to biological systems • describe the non-cyclical nature of energy flow • establish the relationship of the following in food web: • Producer • Consumer • Herbivore • carnivore • Decomposer • food chain

10. Powering the Ecosystem • Power must constantly be supplied for the CPU, Monitor, USB Hub… etc to keep working. This is because energy is constantly lost to the surroundings in the form of heat (or light in the case of the monitor). • Once the power is cut, energy is not supplied, everything cease working. • In an ecosystem, energy flows from one organism to another much like how electrical energy flows from one peripheral to another. • An ecosystem is like a huge computer network with lots of peripherals linked by USB hubs. • There is only one source of power, all other peripherals depend on this source. • While energy in a computer network flows through cables and wires, energy in an ecosystem flows through the links in the food chain. Producers Green Plants SUN Consumers Caterpillar Printer Monitor USB Hub CPU Keyboard Webcam

11. Producers & Consumers Carnivores are organisms that have a strict diet mainly of eating the flesh of other animals. • We hence call green plants the producers. • And those which feed on the green plants as primary consumers. • Those which feed on the primary consumers are in turned called the secondary consumers. • Plants obtain energy from the Sun through photosynthesis. • Animals obtain energy indirectly from the Sun • Through feeding on plants or on one another. Herbivores are organisms that have a strict diet consisting mainly of plant material only. Secondary Consumers Bird Photosynthesis SUN Primary Consumers Caterpillar Producers Green Plants

12. Decomposers Decomposers are organisms (such as bacteria or fungi) that feed on dead plants and animals, thereby breaking them down into simpler substances. • Eventually all organisms will die. • Their bodies will undergo decompositionbreaking down into simpler substances • This process is accelerated by other organisms known as decomposers. SUN

13. Non-Cyclic Flow of Energy Plants used the energy harvested from the Sun for respiration and other life processes. Only 10% of the energy initially harvested becomes available to the primary consumers. Energy is always lost along a food chain. It cannot be recycled, hence we say its flow through a food chain is non-cyclic. SUN Most of the energy obtained by the primary consumers are expended through cellular respiration and eventually only about 10% of the energy obtained by the primary consumer is available to the secondary consumer. Hence, energy keeps getting lost through various processes in the form of heat. The heat is not recoverable and cannot be channeled back into the food chain for continual use by the organisms. Thus the flow of energy is non-cyclic. Light energy from the sun is harvested by plants through the process of photosynthesis