Ecological interaction ppt by Sanduni Madarasinghe

1. Sanduni K. Madarasinghe
University of Ruhuna

2. “Study of the inter-relationship between biotic and abiotic
component as well as the relationships among the individuals of the
biotic component”
Ecology
Biotic factor Abiotc factor Inter-relationships
Competition
Neutralism
Commensalism
Amensalism
Mutualism
Predation,
Parasitism, Herbivory
Matter
Energy
Plants and animals
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3. Types of Interactions
Type Effect on
Species 1
Effect on
Species 2
Amensalism - 0
Neutralism 0 0
Commensalism + 0
Competition - -
Mutualism + +
Predation, Parasitism,
Herbivory
- +
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4. Amensalism
• Any relationship between organisms of different species in
which one organism is inhibited or destroyed while the
other organism remains unaffected
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5. Example 1:
• Penicillium secrete penicillin, a chemical that kills bacteria
Penicillium sp. Penicillium sp. cultured with a
bacteria (Staphylococcus aureus)
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Penicillium
Staphylococcus

6. Example 2:
• Allelopathy involves the production and release of chemical
substances by one species that influence the growth,
survival, and reproduction of other organisms
• These allelochemicals seem to have no direct use in
metabolism
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7. Examples for Allelopathy:
• Black Walnut (Juglans nigra) trees excrete juglone, that
inhibit the growth of nearby trees, shrubs, grasses, and herbs
• The leaf litter and root exudates of some Eucalyptus species
are allelopathic for certain soil microbes and plant species
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8. 8
Casuarina equisetifolia litter completely suppresses germination of understory plants

9. References
• A text book of Plant Ecology (R.S. Ambasht)
• A text book of Plant Ecology (R.S. Shukla)
• http://www.allelopathyjournal.org
• http://csip.cornell.edu/Projects/CEIRP/AR/Allelopathy.htm
• Daizy R. Batish, Harminder Pal Singh (1998) Role of Allelopathy
in Regulating the Understorey Vegetation of Casuarina
equisetifolia. Environmental Forest Science, Vol.54 (Forestry
Sciences) pp 317-323
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