Ecology: Chapters 52-54

1. Ecology: Chapters 52-54

2. Ecology= The study of the interaction between organisms and their environment. Environment (to ecologists) = Surrounding Biotic and Abiotic factors Biotic: living – animals, plants, bacteria… Abiotic: nonliving – temp, light, water…

3. Habitat: the kind of setting in which an organisms is: usually found (cactus – desert) • Niche: the interrelationships (“role”) of an organism with its physical environment and with other plant and animal populations in its community. • Population: all organisms of the same species -- in a specific area • Community: all the populations inhabiting a specific area. Would include: • Producers: photosynthetic &/or chemosynthetic • Consumers: herbivores, carnivores, omnivores and detritivores (decomposers & scavengers) Chemosynthetic tubeworm

4. Biome: Major community, classified by dominant vegetation, specific soil & climate: • Tropical Forest: near equator, sunny, warm, variable rain (rain forest = most species rich). • Savanna: grass, few trees, wet & dry seasons, frequent fire, grazing animals

5. Deserts: arid, temperature extremes, very low precipitation. • Chaparrel: fire-adapted evergreen shrubs, along coasts, mild rainy winters, long, hot, dry summers

6. Temperate Grasslands: cool climate, rich deep soil, periodic fire and drought. • Temperate Deciduous Forests: midlatitudes, enough rain for large trees with seasonal leaf drop • Taiga: coniferous or boreal forest, long, cold, snowy winters, short summers.

7. Tundra: occurs at the northernmost limits of plant growth (artic tundra) and at high altitudes (alpine • tundra): very cold, little precipitation, small plants (permafrost) • Freshwater: rivers, lakes, ponds, streams. • Vertical stratification of light (photic / aphotic) & temp.

8. Marine: estuaries (transition between fresh/salt), coral reefs, oceanic pelagic (open ocean) Horizontal Classification: Intertidal zone:shore, subject to tides Nertic zone: shallow, over continental shelf Oceanic zone:deep, (benthos = ocean bottom) Vertical Classification: Pelagic zone: open water, any depth except floor, divided into photic / aphotic regions Benthic zone:ocean floor, very cold, chemosynthesis = food chain base

9. Population Dynamics: Demography: Study of a population’s vital statistics (birth / death rate, immigration / emigration, age structure, sex ratios…) Density: number of individuals per unit area or volume Dispersion: pattern of spacing for individuals within the boundaries of the population

10. Population Growth: Exponential Growth:no restrictions, population is at biotic potential, J-curve if graphed Logistic Growth: population growth is restricted (due to limiting factors); related to carrying capacity. Carrying Capacity (K):maximum # of organisms the environment can support

11. Density Dependent Limiting factors: intraspecific competition, predation, parasites, pathogens. Density Independent Limiting factors:weather, natural disasters, habitat disruption.

12. Symbiotic Relationships: Parasitism: one organism is harmed, other benefits Commensalism: one organism benefits, other is not affected Mutualism: both organisms benefit Cowbirds are brood parasites The lichen consists of a fungus and an algae growing together. The fungus gets food from the photosynthesizing algae and the algae gets a place to live. Anemonefish are immune to the sting

13. Ecological Succession: A change in species composition over time; one community replaces another. Primary Succession:occurs in lifeless region (volcanic island…) Secondary Succession: occurs in a cleared region with intact soil (forest clearing, crop planting)

14. Biogeochemical Cycles: Remember – energy does NOT recycle!!! Other Elements do. Water Cycle: The quantity of water on Earth is constant. It cycles via the following processes: Enters atmosphere: via evaporation from bodies of water, transpiration from plants, and respiration from all organisms. Returns to land:via precipitation

16. Carbon Cycle: Enters atmosphere: via respiration from all organisms, burning of wood and fossil fuels. Returns to land:via photosynthesis

18. Nitrogen Cycle: Enters atmosphere: via denitrifying bacteria in soil. Returns to land:via nitrogen-fixing bacteria (& then plants…)

20. Energy Transfers: food chains, food webs show how energy passes through trophic levels. • Energy Pyramid: also called pyramid of net productivity. • Only 10% of the energy passes to the next level: must have mostly producers…

21. Biomass Pyramid: mass of producers is usually highest

22. Pyramid of Numbers: numbers of organisms usually highest at: producer level (this is the only one that might not be a pyramid shape). *Not always a pyramid!

23. Primary Productivity = the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem. There are two aspects of primary productivity: •Gross productivity = the entire photosynthetic production of organic compounds in an ecosystem. •Net productivity = the organic materials that remain after photosynthetic organisms in the ecosystem have used some of these compounds for their cellular energy needs (cellular respiration). Since oxygen is one of the most easily measured products of both photosynthesis and respiration, a good way to gauge primary productivity in an aquatic ecosystem is to measure dissolved oxygen: