Chapter 50: An Introduction to Ecology & Biosphere 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

Subfields of ecology Organism ecology Population 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

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

Fires, hurricanes, natural disasters Local/seasonal effects of climate 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

Occupy the largest part of the biosphere 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)

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

Ponds- Small bodies of standing H2O 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

Geographic distribution based mainly on regional variations in climate 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 Types of biomes Tundra/permafrost Taiga/coniferous forest Temperate deciduous forest Temperate grasslands Chaparral Deserts Savannas Tropical rainforest