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Unformatted text preview: BIOL 110: Principles of Biology
Spring 2005 Lecture 44, W 5/18/05
http://www.smccd.net/accounts/staplesn/biol110/ • Quiz #7 (Last Quiz!): is up since Fri.
– (microbes, plants, animal Tissues & homeostasis).
– http://smcwebtest.smccd.net/accounts/staplesn/index.tpx • YOU MUST TAKE ALL QUIZZES by FRIDAY!!!
– If you miss more than 1 quiz, you will likely fail the course!! • Final REVIEW session, Friday, 12:30-2pm (lab). • Next: 29 & 30, (32). REVIEW:
• Ch. 29: Community Structure & Biodiversity
– Community, Niche – Species interactions – symbiosis, competition…. competition… – Predator/prey coevolution, cycles coevolution, TODAY:
• Ch. 29: Community Structure & Biodiversity
– Species interactions – Parasitism – Succession, Diversity • Ch. 30: Ecosystems
– Food Webs & Energy flow; Biogeochemical Cycles 1 IV. Parasitism
• Parasites drain nutrients from their hosts and live on or in their bodies • Natural selection favors parasites that do not kill their host too quickly • TYPES:
• cuckoo • cowbird – Microparasites – Macroparasites – Social parasites – Parasitoids
• Only parasitic during a part of life cycle. IV. Succession
Change in the composition of species in a community over time • Primary succession - new environments • Secondary succession - communities were destroyed or displaced 2 A. Pioneer Species
• Species that colonize barren habitats
– Eg: Lichens, small plants with brief life cycles Eg: – Like Edgewood Park communities:
• lichens, coyote brush, small weeds & flowers, legumes (pea, clover, vetch, lupine) • Improve conditions for other species, who then replace them B. Climax Community B.
• Stable array of species that persists relatively unchanged over time • Succession does not always move predictably toward a specific climax community;
– other stable communities may persist 3 Diversity by Latitude
• Diversity of most groups is greatest in tropics; declines toward poles
• Diversity is self-promoting!! Ant diversity Ecosystems
Chapter 30 4 I. Ecosystem
• An association of organisms and their physical environment, • Interconnected by ongoing flow of energy and a cycling of materials Modes of Nutrition
• Autotrophs (“self feeders”)
– Capture sunlight or chemical energy – Producers • Heterotrophs (“feeders on others”)
– Extract energy from other organisms or organic wastes – Consumers, decomposers, detritivores 5 Simple Ecosystem Model
• Nutrients are recycled • Energy flows only one way!! energy input from sun PHOTOAUTOTROPHS (plants, other producers) nutrient cycling HETEROTROPHS (consumers, decomposers) energy output (mainly heat) Consumers
• Herbivores • Carnivores • Parasites • Omnivores • Decomposers • Detritivores
rodents, rabbits birds rodents, rabbits birds fruits insects SPRING fruits SUMMER insects Seasonal variation in the diet of an omnivore (red fox) 6 Trophic Levels in Prairie
Fourth-level consumers (heterotrophs): 5th Top carnivores, parasites, detritivores, decomposers Third-level consumers (heterotrophs): Carnivores, parasites, detritivores, decomposers 4th Second-level consumers (heterotrophs): 3rd Carnivores, parasites, detritivores, decomposers First-level consumers (heterotrophs): 2nd Herbivores, parasites, detritivores, decomposers Primary producers (autotrophs): 1st Photoautotrophs, chemoautotrophs Food Chain
marsh hawk • A straight line sequence of who eats whom
upland sandpiper • Simple food chains are rare in nature garter snake cutworm plants 7 Food Web
MARSH HAWK HIGHER TROPHIC LEVELS Complex array of carnivores, omnivores and other consumers. Many feed at more than one trophic level continually, seasonally, or when an oppportunity presents itself CROW UPLAND SANDPIPER GARTER SNAKE FROG SPIDER SECOND TROPHIC LEVEL Primary consumers (e.g., herbivores) FIRST TROPHIC LEVEL Primary producers WEASEL BADGER COYOTE CLAYCOLORED SPARROW EARTHWORMS, INSECTS (E.G., PRAIRIE VOLE GRASSHOPPPERS, CUTWORMS) POCKET GOPHER GROUND SQUIRREL Predators feed on multiple prey, and prey are eaten by multiple predators. Energy Losses
• Energy transfers are never 100 percent efficient • Some energy is lost at each step • Limits the number of trophic levels in an ecosystem 8 Pyramid of Energy Flow
• Primary producers trapped about 1.2 1.2 percent of the solar energy that entered percent the ecosystem • 6-16% passed on to next level top carnivores carnivores herbivores producers 21 383 3,368 20,810 kilocalories/square meter/year decomposers detritivores All Heat in the End
• At each trophic level, the bulk of the energy received from the previous level is used in metabolism • This energy is released as heat energy and lost to the ecosystem and • Eventually, all energy is released as heat 9 II. Biogeochemical Cycle
• The flow of a nutrient from the environment flow to living organisms and back to the environment • Main reservoir for the nutrient is in the environment Three Categories
• Hydrologic cycle
– Water • Atmospheric cycles
– Nitrogen and carbon • Sedimentary cycles
– Phosphorus and sulfur 10 A. Hydrologic Cycle
atmosphere wind-driven water vapor wind40,000 evaporation precipitation from ocean into ocean 425,000 385,000 evaporation from land plants (evapotranspiration) 71,000 surface and groundwater flow 40,000 precipitation onto land 111,000 ocean land Hubbard Brook Experiment
• • • A watershed was experimentally stripped of vegetation All surface water draining from watershed was measured Removal of vegetation caused a six-fold increase in the sixcalcium content of the runoff water
losses from disturbed watershed time of deforestation losses from undisturbed watershed 11 ...
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