AMENSALISM AND ANTIBIOSIS

AMENSALISM IS A SITE-SPECIFIC RELATIONSHIP IN WHICH ONE POPULATION IS INHIBITED WHILE THE OTHER IS UNAFFECTED. A SIMPLE EXAMPLE IS THE SHADING OUT OF CERTAIN PLANTS UNDER TALL TREES. THE TREES REDUCE THE AVAILABLE SUNSHINE AT GROUND LEVEL, AND NUMEROUS PLANTS CANNOT FIND ADEQUATE LIGHT IN THE SHADE. HENCE, ONLY SHADE TOLERANT PLANTS WITH LOWER LIGHT REQUIREMENTS CAN SURVIVE AS GROUND COVER IN THE FORESTS.

ANTIBIOSIS IS A SPECIFIC TYPE OF AMENSALISM IN WHICH ONE ORGANISM PRODUCES A METABOLITE THAT IS TOXIC TO OTHER ORGANISMS. THE BEST KNOWN EXAMPLE IS MOLD, PENICILLIN, WHICH PRODUCES AN ANTIBIOTIC SUBSTANCE  CAUSING THE DEATH OF MANY BACTERIA. MANY PLANTS ALSO PRODUCE SUBSTANCES  WHICH ARE HARMFUL TO ANIMALS, FOR EXAMPLE, ALGAE BLOOMS OF SOME BLUE, GREEN AND RED ALGAE PRODUCE CHEMICALS THAT ARE TOXIC TO FISH.