Ecology
– the study of the interdependence of living organisms
– the interdisciplinary scientific study of the distributions, abundance and relations of organisms and their interactions with the environment
"It is an obvious truth, which has been taken notice of by many writers, that population must always be kept down to the level of the means of subsistence; but no writer that the Author recollects has inquired particularly into the means by which this level is effected..." -- Thomas Malthus, 1798
Parts of an Ecosystem
• Biotic factors– Living things that affect the organisms
• Abiotic factors– Non-living things that affect the organisms
• Biotic and abiotic factors are interdependent
The Niche
• A niche is a way of life• Includes all aspects of lifestyle– Range of tolerable conditions– Means of acquiring resources– Number of offspring– Interactions with environment– Time of day of activity– And on and on and on and …..
Acclimation
• Tolerance curves can be affected– Acclimation– Homeostasis
0 10 20 30 40 500
10
20
30
40
50
60
Acclimated to 5° CAcclimated to 25° C
Niche differences
• Specialists–Have very narrow
niches and tend to specialize on utilizing a resource other organisms are unable to use.
Measuring productivity
• Biomass– Mass of organic material produced in an ecosystem
• Gross primary productivity (GPP)– Rate at which producers capture solar energy and
produce organic material• Net primary productivity (NPP)– Rate at which biomass accumulates– Kcal/m2/yr= GPP– rate of respiration in producers
Net Primary Productivity
Estuary
Tropical rain forest
Savanna
Woodland and shrubland
Lakes and streams
Tundra
Desert Scrub
0 1000 2000 3000 4000 5000 6000 7000 8000 900010000
NPP (kcal/m2/yr)
NPP (kcal/m2/yr)
Consumers
• Herbivores- eat producers• Carnivores- eat consumers• Omnivores- eat producers and consumers• Detritivores- eat dead stuff or excrement– Decomposers- break down complex organic material
Energy Flow
• Trophic levels– Indicates the number of energy transfers
• Only 10% of the energy in one level is available to the next
Tertiary consumers
Secondary
consumers
Primary consumers
Producers
Consumers
Decomposers Inorganic Nutrients
Producers
Energy and Nutrient Flow
Energy
Nutrients
Consumers
Decomposers Inorganic Nutrients
Producers
Energy and Nutrient Flow
Energy
Nutrients