Lecture 2 Topic: Autecology - the ecology of single species.
Section objectives:
Ecological factors: abiotic, biotic, anthropogenic
Limiting factors: critical factors and tolerance limits. Liebig 's law of the minimum and Shelford's principle of tolerance limits
Biotic and abiotic interactions
1. Ecological factors:
Abiotic factors - the nonliving components of an ecosystem.
Biotic factors - the living components of an ecosystem.
Anthropogenic factors – factors that are caused by human activities.
Ecological factors |
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Abiotic |
Biotic |
Anthropogenic |
Meteorological: climatic; temperature, humidity, pressure, wind |
Zoogenic: animals relationships |
Economical : using natural resources for survival |
Geophysical: radiation, relief, magnetic |
Phytogenic: plants relationships |
Technogenic: using machines and complex technical equipment to reach definite purposes |
Chemical: components of atmosphere, water, soil chemistry and structure, acidity |
Microorganismic: microorganisms relationships |
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physical factors interact with one another: Example: Rains → Flood → Change the chemical soil composition.
Biotic factors also interact in many ways:
Possible interactions between Organisms in a community |
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Kind of interaction |
Organism 1 |
Organism 2 |
Competition [interspecific = between species, intraspecific = between individuals of one species] |
harmed |
harmed |
Predation [predator-prey system: herbivory (rabbit-grass; giraffe-trees), carnivory (wolf-deer, fox-hare), omnivory (bear-elk, or fruits)] |
benefited |
harmed |
Symbiosis: the relationship between different species living in close association with one another: |
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Parasitism [a parasite secures its nourishment by living on or inside another organism called the host – helminthes; fleas, lice] |
harmed |
benefited |
Allelopathy [the type of interaction in which one organism release allelochemicals that harm another organism – flowers with strong smell kills other: tulip-narcissus, rose-pink, lily of the valley, lilac] |
benefited |
harmed |
Commensalism [interaction that benefit one participant and have no effect on the other – remoras and sharks; leguminous-nitrogen fixing bacteria] |
benefited |
unaffected |
Protocooperation [is a noncompulsory interaction which can also benefit both participants – fungus + algae = lichen] |
benefited |
benefited |
Mutualism = obligate symbiosis [both participants benefit, but this interaction is essential to the survival or reproduction of both participant – pollination of some flowers by insects, birds, or bats; termites and internal protozoa] |
benefited |
benefited |
Most obvious are Predation and Competition - antagonistic relationships