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 Overlapping niche requirements

Keystone species 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

Chylorphyll abundance

Secondary production

Measuring Productivity

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