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Community Collection of species populations Members from most kingdoms Linked in a web Mainly predator/prey Environment & habitat / Dominant species Lake/grassland Sizes Habitats and Niches Habitat: A collection of niches Habitat Physical space where an organism lives Microhabitats Niche The unique position occupied by a particular species in a community – ecological role Each niche unique Occupy overlapping BUT different niches Fundamental vs. realized niche Resource partitioning Darwin’s finches Darwins’ Finches Patchiness Distribution patterns Random Aggregated Conditions & resources not evenly distributed Temporal variability Intraspecific & interspecific competition Events Gradient Regular Plankton patchiness Horizontal, temporal & vertical variability Physical - Water movements Biological – plankton related Light – dark cycle Gamete concentration Predator – prey interactions Trophic interactions and productivity Primary producers, consumers, decomposers Rule of 10% Different communities w/ different# of trophic levels NPP Net Primary Production Trophic interactions and productivity Guilds Keystone species Overlapping niche requirements Limpets Dominant Numerical or biomass abundance Opportunistic species, specialization, generalists Measuring Productivity 6CO2 + 6H2O C6H12O6 (glucose) + 6O2 Increase in biomass over a fixed time period NPP Plankton Measuring Productivity Chylorphyll abundance Secondary production Comparative Ecosystem Productivity Productivity determinants Light, temperature, rainfall, nutrients Tropics, higher latitudes, deserts Photosynthetic efficiency 1-2 % in terrestrial ecosystems – 0.5 % in aquatic habitats Conditions for plant growth not met More secondary production in oceans Detritivores Trophic Interactions & Pollution Material transfer Minerals, vitamins etc. Pollutants Heavy metals, organic chemicals, some light elements Bioconcentration Biomagnification Biotransformation Mercury methyl mercury Mercury Pollution Minimata disease, brain damage, kidney damage etc. Organic methyl mercury Bioconcentration & Biomagnification Succession The change in composition and form of vegetation Immature mature/self-sustaining Primary Succession Pioneer species Xerarch vs. hydrarch succession Secondary succession Climax community Xerarch vs. hydrarch succession Succession Biodiversity Species & genetic & ecosystem diversity biodiversity Ecological diversity Species diversity Genetic diversity Species richness vs. species diversity Tropical forests, coral reefs and tropical lakes Genetic diversity Habitat destruction, pollution and agricultural practices Stability and Resilience Stability – environmental change Persistence, constancy, resilience High diversity = high stability? Tropical rainforest vs. grasslands Biogeography Study of the distribution of organisms Historical & Ecological Vicariant and dispersal distribution Endemic taxa Six major zones
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