Communities and ecosystems Aidas Bertulis 2013, Šiauliai Jurgita Šerniūtė 2013, Kaunas

THE MAIN AIM: OBJECTIVES: To learn about communities and ecosystem. To learn about a food chain and the energy flow in a food chain. To learn about a food web. To find out what the trophic level is. To recognize the pyramid of energy and to learn about the way how energy enters and leaves ecosystems and that nutrients must be recycled. To do a topic-related task.

MAIN CONCEPTS and Lithuanian equivalents Ecology – ekologija; gamtosauga. Ecosystem – ekosistema, ekologinė sistema. Population – populiacija. Community – (augalų, gyvūnų) bendrija, biocenozė Species – rūšis, atmaina; veislė. Food chain – mitybos grandinė. Food web – mitybos tinklas. Omnivore – visaėdis gyvūnas. Organic compound – organiniai junginiai. Habitat – arealas.

Definitions and examples (1): Ecology – the branch of biology that deals with the relations of organisms to one another and to their physical surroundings. Ecosystem – a biological community of interacting organisms and their physical environment: e.g. The marine ecosystem of the northern Gulf has suffered irreparable damage. Population – a community of animals, plants, or humans among whose members interbreeding occurs: e.g. fluctuations in populations of voles. Community – a group of interdependent plants or animals growing or living together in natural conditions or occupying a specified habitat: e.g. communities of insectivorous birds

Definitions and examples (2): Species – a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. e.g. Homo sapiens. Food chain – a series of organisms each dependent on the next as a source of food. Food web – a system of interlocking and interdependent food chains. Omnivore – an animal or person that eats a variety of food of both plant and animal origin. Organic compound – any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. Habitat – environment where species live.

TASK 1 Write a definition for the given concepts and mach them to the pictures.

Answers: i. Organic compound e. Species g. Food web a. Ecology b. Ecosystem f. Food chain j. Habitat c. Population d. Community h. Omnivore

Trophic level The trophic level of an organism defines the feeding relationship of that organism to other organisms in a food chain.

The energy flow in a 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 during photosynthesis. b) Photosynthesis in which light energy is trapped by producers. c) Consumers feeding and passing on energy in the food molecules. 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.

 Pyramid of energy This model shows the typical loss of energy from solar radiation through the various trophic levels. Note how this causes the tapering of the model. The volume of one layer is 10% of the layer below. This is a more typical pyramid of energy. Note that the initial solar energy is not shown. The narrowing shape illustrates the gradual loss of energy progressing along the links of a food chain to higher tropic levels (see above for detail)

Energy enters and leaves ecosystems, but nutrients must be recycled (a) Energy flows: this diagram is a simple version of the pyramid of energy. At each trophic level energy is lost as heat. At the top of the pyramid of energy it tapers to a point showing how all energy is ultimately radiated to space as heat. (b) Matter cycles: new matter is not created, no new carbon, hydrogen or oxygen. Producers (autotrophs) take inorganic molecules and convert them to organic compounds. Consumers feed at different trophic levels taking in organic matter and using it for their own growth. This cycling of matter is the subject of the carbon, nitrogen and water cycle.

ECOSYSTEMS, BIOMES, AND HABITATS TASK 2 ECOSYSTEMS, BIOMES, AND HABITATS Read the text and write one or two questions for each paragraph. Then exchange and answer each other’s questions with a colleague.

A food chain Bushgrass---> Impala ---> Cheetah----> Lion Food chains show a simple linear flow of “who eats who” and therefore the energy and matter flowing through the links in the chain.

A food web The food web is a diagram that shows how food chains are linked together into more complex feeding relationships. http://www.soilfoodwebnewyork.com

A food web has a number of advantages over a food chains including: Shows much more complex interactions between species within a community/ ecosystem; More than one producer supporting a community; A single producer being a food source for a number of primary consumers; A consumer may have a number of different food sources on the same or different trophic levels; A consumer can be an omnivore, feeding as a primary consumer and as a consumer at higher trophic levels. TASK 3: DESIGN A FOOD CHAIN FROM 5 OR MORE ORGANISMS. Example:

References Click4Biology: 5.1 Communities & ecosystems. Internetinė prieiga: http://click4biology.info/c4b/5/eco5.1.htm Oxfordo anglų kalbos žodynas. Internetinė prieiga: http://oxforddictionaries.com/spellcheck/english/

HOMEWORK: Example: Design a food web from 15 or more organism. For both alternatives write names and short definitions near pictures. Prepare to present in class (3-5 min.)