Chapter 50: An Introduction to Ecology & Biosphere

1. Chapter 50: An Introduction to Ecology & Biosphere Ecology Scientific study of the interactions between organisms & their environment **Environment= biotic & abiotic factors Difficult to conduct experiments & control variables Test hypothesis by manipulation of field populations & communities Use of mathematical models Manipulation of models to simulate long term effects

2. Subfields of ecology • Organism ecology • response of organism to abiotic factors • Physiological/morphological ecology • Evolutionary ecology • Behavioral ecology • Population ecology • examines factors influencing population size • Community ecology • studies interactions (predation, competition, disease, etc.) of all organisms in an area • Ecosystem ecology • focuses on energy flow & chemical cycling between abiotic factors & communities

3. Biotic factors influencing biomes • Predation • Parasitism • Disease • Competition • Dependence on other species (ex. Pollinators) Abiotic factors influencing biomes • Temperature • Varies regionally • Influences metabolism • Most organisms unable to regulate body temperature • Endothermic organisms function best at temp to which they are adapted • Water • Precipitation patterns vary regionally • Aquatic organisms contend with osmoregularity • Terrestrial organisms contend with desiccation • Sunlight • Latitudinal & seasonal variations affect organisms • Affects producer distribution which influences other organisms • Cues seasonal behavioral events

4. Wind • Global air circulation & wind patterns differ regionally • Effects evaporation, convection, transpiration, & morphology of organisms • Rocks & soil • Minerals, pH & physical structures affect distribution of plants & therefore animals • Fires, hurricanes, natural disasters • Periodic disturbances effect biological communities • Local/seasonal effects of climate • Bodies of water, mountains, seasons affect organisms • Examples- lake effect snow, lake turnover

5. Aquatic biomes • Occupy the largest part of the biosphere • Marine biomes • [NaCl]=3% • 75% of all biomes • Freshwater biomes • [NaCl]<1% • Vertical stratification • Thermocline- narrow separation between warm & cold H2O • Light penetration • Photic zone- sufficient light penetration for photosynthesis • Aphotic zone- no light penetration; no photosynthesis • Open H2O vs. bottom • Pelagic zone- open water • Benthic zone- bottom layer; bottom dwellers (benthos) feed off detritus (dead organic matter from upper zones) • Abyssal zone- deepest region (ocean only)

6. Depth of H2O & distance from shore • marine • Intertidal zone- covered by tide part of day • Neritic zone- shallow regions close to shore • Oceanic zone- far from shore • Freshwater • Littoral zone • shallow waters • close to shore • inhabited by algae, plant, mollusk, insect, crustaceans, fish, & amphibians • Limnetic zone • deep waters • do not support rooted plants • inhabited by variety of phytoplankton & cyanobacteria

7. Freshwater biomes • Ponds- Small bodies of standing H2O • Lakes- Large bodies of standing H2O • Oligotrophic lake • Deep, clear, & nutrient poor • Mesotrophic lake • Eutrophic lake • Nutrient rich; support large, productive phytoplankton community • Streams & rivers- flowing habitats • Chemical & physical characteristics vary from source to mouth • Wetlands- areas covered with water & supporting hydrophytes (H2O plants) • Diverse biomes • Important for flood control & H2O filtration • Estuaries- area where fresh H2O river meets the ocean • Often borders wetlands & are called mudflats & saltmarshes • Salinity varies spatially & daily • Diverse communities • Breeding ground for marine invertebrates, fish, & waterfowl Marine biomes • estuaries • Intertidal zone • Coral reefs- tropical H2O supports highly diverse & productive communities • Ocean zones

8. Terrestrial Biomes • Geographic distribution based mainly on regional variations in climate • Stratification • Forest biomes • Canopy • Low tree stratum • Shrub understory • Ground layer/forest floor litter • Root layer • Non-forest biomes • Herbaceous layer/shrub layer • Ground layer/forest floor litter • Root layer • Types of biomes • Tundra/permafrost • Taiga/coniferous forest • Temperate deciduous forest • Temperate grasslands • Chaparral • Deserts • Savannas • Tropical rainforest