Ecology Your share in the biosphere

Levels of Organization Biosphere – Earth & its atmosphere that supports life Ecosystem – Organisms & abiotic materials in 1 place Community – Different species of an ecosystem Population – Members of single species of an ecosystem Organism

Interdependence All organisms interact with other organisms – Plant, animal, bacteria, fungi, protists, & archaea All organisms interact with their surroundings – Food, shelter, air, moisture, temperature, etc… Abiotic environment is changed by organisms – Erosion, fertilization, pH, mineral cycles, etc…

Community Living

Ecosystem’s Components Biotic factors – Living organisms Abiotic factors – Nonliving materials, conditions, energy Tolerance curve – Survival range for given condition – Acclimation: organisms’ ability to adjust tolerance Niche – Species’ specific role within its environment

Species Interaction Predation – Herbivores : eats plants – Carnivores : eats meat Competition – Interspecific competition: > 2 species, 1 resources – Competitive exclusion:2 species,1 resource, 1 wins Fundamental niche vs. realized niche Character displacement (competition-driven evolution)

“Food Web”

Species Interaction, continued Symbiosis – Parasitism Similar to predation but death of host is not immediate Either external (ectoparasites) or inside (endoparasite) – Mutualism Mutually beneficial Ants & Acacia plants; pollinators & nectar/ food – Commensalism One benefits & other is unaffected Cattle egrets & cape buffaloes

Mutualism

Commensalism

Ecological Succession Primary Succession – New life on previously barren land (no soil) – Bare rock, sand dune, new island/ lava flow – Pioneer species predominate early in succession Secondary Succession – Replacement following disruption of existing life – Soil present after forest fire, flood, storm, humans – Weeds/ wild flowers->perennials-> shrubs-> trees ***Climax community = stable end point ***

Levels of Succession

Conservation of Energy Sun is Earth’s ultimate source of energy Autotrophs = Producers of biomass – Photosynthesis & chemosynthesis Heterotrophs = Consumers – Herbivores, Carnivores, Omnivores, Detritivores Energy flows through trophic levels – Food chains & food webs – Only ~ 10% of energy is transferred to next troph

Biochemistry connects it all!

Ecosystem Recycling Water cycle Surface H 2 O  evaporation  clouds  precipitation  runoff  surfaceH 2 O  percolation  groundH 2 O  plants  transpiration  clouds Carbon cycle – Atmospheric CO 2  photosynthesis  plant life  animal life  respiration  Atmospheric CO 2  animal/plant death  Atmospheric CO 2  fossil fuel  combustion  Atmospheric CO 2

Ecosystem Recycling, continued Nitrogen cycle Atmospheric N 2  N-fixation by bacteria (root & soil)  NH 3 & NH 4 +  Nitrification (via bacteria)  NO 3  Denitrifying soil bacteria  N 2 in air OR  NO 3  Assimilation into plants  herbivores  urine/ feces/ plant or animal death/ decay  decomposers  Ammonification  NH 3 & NH 4 + Phosphorous cycle Rock erosion  PO 4 3-  soil & water  plant absorption  herbivores  carnivores/omnivores  waste/ death/ decay  soil & water