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