Lecture 1 4/6/10 2:27 PM Ecology: the study of the interaction of organisms with one another in an environment Organismal ecology: studies how an organisms structure, physiology, and behavior meet environmental challenges Includes physiological, evolutionary, and behavioral ecology Population ecology: focuses on factors affecting how many individuals of a species live in an area; distribution and abundance of a particular species Population: group of individuals of the same species in an area Community ecology: examines how interactions among species affect community structure and organization Community: group of populations of different species in an area Ecosystem ecology: emphasizes energy flow and chemical cycling among various biotic and abiotic components (lakes) Ecosystem: the organisms in an area and the physical factors with which they interact Landscape ecology: focuses on the factors that generate patterns of ecosystems in a geographic region Physical and chemical context Soil science, geography, history Landscape: mosaic of connected ecosystems Global ecology: how movement of energy and materials affects the distribution and functioning of organisms across the biosphere Biosphere: the global ecosystem, the sum of all the planet?s ecosystems History of Ecology: From age of exploration Technology let people travel around to different places to make observations Ernest Haeckel: termed ecology For the relationship between animals Warming: wrote first book on plant ecology Tansley: urged more experimental approach to the study of ecology; termed ecosystem Modern ecology is an integrative science of complex systems, using the full range of scientific approaches Observation (most fundamental) Experimentation Analysis Simulation Ecological approaches can be applied to problems Can apply to human systems, economics, mathematics, politics Ecological methods: locust example Outbreak of locusts What causes this? What factors influence the locust distribution and abundance? Extremes of temperature/moisture Predators Competitors Host plant quality/quantity Hypothesis testing Not total control of place (more variables) Locust populations are high when bird population is low Inverse relationship Predation levels determine locust numbers Use linear regression Graphs imply a correlation between variables Correlation does not mean causation In an experiment, remove predators Experimental group Control group Any differences should be due to predation Perform replicates Analysis: could use statistical tests Do other experiments Moisture Create simulation models to assess affects of certain variables What limits distribution and abundance? Dispersal Behavior Biotic factors: interactions with other organisms Food, predation, parasitism, competition, disease Abiotic factors: physiological tolerance limits Abiotic factors that can limit organisms? ranges Temperature Affects biological processes Cells freeze below 0 C, proteins denature above 45 C Some adaptations Mammals and birds expend energy to regulate internal temperature Range limits of many species determined byt the lowest critical temperature for the most vulnerable life stage Tree vs. seedling Important geographical gradients Latitude, elevation Insect development is very temperature dependent Coral reefs are abundant only in warm water because of the increased rate of deposition of carbonate skeletons Cannot get too high! Atlantic Lobster: lives in water from 0-17 C, but breed in water warmer than 11 C Frost is most important factors for geographical distribution of plants Cacti Sugar Maple Water availability Plants can be tolerant to flooding Plant?s toleration of dry environments Adaptations (cacti) Animal distribution linked to plant distribution Animals have adaptations for water conservation, tolerance of excess water Gas partial pressure Wind Increases heat loss by evaporation/transpiration and convection Increases rates of water loss Can intensify wave action in water Flagging of tree limbs due to wind Individual ecology Sprouts facing wind are mechanically disrupted Relief/topography UV Damage to DNA Salinity Animals Freshwater fish tend to gain excess water; constantly eliminate water Marine fish lose water and must drink water to compensate; salt excreted at gills and kidneys Plants Halophytes: tolerate high salt concentrations Irrigation can result in salt accumulation due to evaporation Light availability Water absorbs light so most photosynthesis in aquatic ecosystem occurs near the surface Red algae have pigments that absorb blue-green light so they can live deeper High light levels can cause stress Space Rocks and soil Physical structure Mineral composition pH most terrestrial plants grow best at pH=6.5 Decreased pH in soil slows decomposition, N cycling, leaches calcium from soils Acid Rain: pH < 5.6 Results from burning fossil fuels Fish are most vulnerable to low pH in juvenile life stages Species diversity is generally lower in acidic lakes and streams Experiment Added calcium carbonate increased pH, available N and rates of nitrification, sugar maple growth and mycorrhizal associations Like titration nutrient availability
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