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ECOLOGY 0370Introduction1. What is ecology?- Haekel (1866): study of relationship of animals to their environment- Now expanded to all organisms- Yet vague, what is really studied?- Some basic observationso Many species on Earth; approx. 1.9 million named and describedspecieso Each has unique, limited distribution, unique geographical locations—no species that occurs everywhereo Abundance of each species varies in space and timeo Not all species occur togethero Species occur in limited sets, or communities- Why should the world be organized like this?a. General definitionsi. Scientific natural history- Natural history: the study of nature and natural phenomena- Not quite appropriate; includes topics peripheral to ecology (e.g. astronomy)ii. Structure and function in nature- The “working” of nature- But seems to imply homeostasiso Gaia hypothesis: world has world-wide homeostasiso we don’t know if it is homeostaticb. Formal definitioni. “Ecology is the scientific study of the interactions that determine the distribution, abundance, and co-occurrence of organisms”ii. simple enough, but subtlei. interactions occur between organisms and their environmentsii. “environment” includes other organisms; including conspecifics- conspecifics: members of a given speciesiii. focuses on organisms, not environments (unlike environmental science)iv. also deals with who occurs with whom and why and who doesn’t occur with whom and why; community membership c. Relationship to other biological sciencesi. Ecology complex, syntheticii. Has close ties to many natural sciencesi. Geneticsii. Evolutioniii. Behavioriv. Phyiologyd. Historyi. See handout of dates and events2. Goals of ecologya. Descriptiono EX: Indigo bunting yearly cycleo Breeds in Eastern USo Migrates south in fallo Stays in central America during wintero Migrates northb. Identification of proximate (immediate) causeso EX: causal cue of Indigo bunting fall migrationo Stephen Emlen: proposed difference in photo period; experiment with birds in planetarium, altered photo periodsand measured footprints made with inkpad; found birds wanted to migrate south in response to mid-August photo periodc. Identification of ultimate (evolutionary) causeso Causes that give rise to proximal causeso EX: evolutionary reason for migrationd. Prediction—use knowledge to predict eventso EX: population response to global warming; American Beech tree response to temperaturee. Application—applied ecologyo EX: steps to protect extinction under global warming3. Levels of Studya. Primarily populations and communities- Population: group of conspecifics- Community: set of populations that co-occurb. Also individuals, ecosystems, and the biosphere- Biosphere: thin shell of Earth capable of supporting lifeo Ecosystem: set of communities and their abiotic surroundings Communities- Populationso Individuals/ramets4. The scientific method in ecology- Handout5. Approachesa. Experimental- Keep as many variables as possible the same- Manipulate one variable, chart responseo Eliminates confounding variables- Requires a control group and a treatment groupb. Modeling/Simulation- Establish qualitative or quantitative “image” of the basics of complex systems- Run model or simulation- Determine if result is a pattern seen in naturec. Comparative- Take advantage of similar natural circumstances that differ in some or few attributeso EX: islands and island size Community smaller on smaller island Island size dictates the number of co-occurring


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Pitt BIOSC 0370 - Lecture notes

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