Keystone Ecology Review
Jan 01, 2016
Keystone
Ecology Review
Levels of Organization
• Ecosystem—biotic & abiotic
• Community—all biotic factors
• Pollution—only one group (species) of organisms
Comparing Biotic and Abiotic FactorsBiotic—all living or once living organismsAbiotic—all non living factors
Food Chain in an Antarctic Ecosystem• A food chain shows ONE possible feeding pathway.• The arrow always goes into the mouth of the eater
Food Web in an Antarctic Ecosystem• A food web shows all possible feeding relationships in a
ecosystem
Energy Transfer Through Trophic Levels• Only 10% of energy from each level is available to be
passed on to the next level. • Most of it gets used or lost as heat. That’s why more
organisms on bottom than top
Energy Pyramid
Symbiosis—close, long term relationship b/w to organisms (at least one benefits
Parasitism, mutualism, commensalism
Parasitism
The parasite benefits while the host is hurt
Mutualism
• Both organisms benefit
Commensalism• One benefits while the other is neither hurt nor
helped
Recycling Matter through the Ecosystem
Water Cycle
• Key processes are– Evaporation– Transpiration– Precipitation
Carbon CyclePhotosynthesis & Respiration are the two main steps
Nitrogen Cycle• Nitrogen fixing bacteria change nitrogen gas into a useable
form for nitrogen for plants (& then animals) • Denitrification puts nitrogen gas back into the atmosphere
Phosphorus Cycle
Phosphorous moves from phosphate deposited in rocks , to the soil, to living organisms and finally to the ocean
Succession—gradual sequential regrowth of a community of a species in a area
Two Types:Primary
Secondary
Primary SuccessionOccurs where the land has not supported any prior life, bare rock, newly formed islands (soil lacks nutrients or any life left behind)
Secondary SuccessionOccurs where soil has previously existed and some life is still left behind.
Ecological Succession at Glacier Bay
• Carrying capacity— number of individuals the environment can sustain
• Limiting factor— any factor the restrains the growth of a population (space, sunlight, food, water, mates)
Carrying Capacity of Reindeer in Pribilof Islands