Population Interactions

I.  Neutralism

II.  Positive interactions
  A.  Commensalism
     B.  Synergism (protocooperation)
     C.  Mutalism (symbiosis)

III.  Negative interactions
  A.  Amensalism (antibiotics and allelopathic compounds)
     B.  Competition
     C.  Predation
          1.  predator-prey models
          2.  phagotrophy
          3.  labelled prey (Sherr and Sherr)
     D.  Parasitism

IV.  Interactions with Higher Organisms
     A.  Microorganisms and Plants
           1.  Plant roots
               a.  Mycorhizae [p. 591]
               b.  Nitrogen fixation in nodules (Rhizobium spp. and legumes)
                   - Legumes - pea, bean, clover, alfalfa, soybean
                        root nodules - Rhizobium and Bradyrhizobium  [p. 596]
                        stem nodules on a tropical legume - Azorhizobium
                   - Alder tree roots - Frankia spp. root nodules  [p. 603]
          2.  Lichens (consortium of alga [or cyanobacterium] and fungus)
          3.  Microbial plant pathogens
                Agrobacterium spp. - cause tumerous growths or galls on many types of plants

     B.  Microorganisms and Animals
          1.  Predation of microorganisms by animals
          2.  Predation of nematodes by fungi
          3.  Cultivation of fungi by ants, beetles, and termites for food (cellulase production needed)
          4.  Invertebrate symbioses and mutalisms with microorganisms
               a.  Teredo shipworms (N2 fixing cellulase-producing proteobacteria in gills)
               b.  Zooxanthellae (coral and photosynthetic eucaryotic dinoflagellates; other invertes 
                    have also established symbioses with photosynthetic eucaryotes or cyanobacteria)
               c.  Riftia pachyptila and chemolithotrophic bacteria in trophosome at deep sea 
                    hydrothermal vents (sulfur oxidation and CO2 fixation)
               d.  Mytilidae mussels and symbiotic methane-oxidizing bacteria (not chemoautotrophic;
                    don't fix CO2 but obtain carbon from methan) in their gills (methane seeps in Gulf of 
                    Mexico - Florida escarpment and salt domes)
          5.  Digestive tract ecosystems 
               a.  Termite hindguts
               b.  Vertebrate associations
                    - rumen microorganisms in cows and other rumenants
                    - human enteric bacteria
                    - lumenescent organs of deep sea fish (Vibrio and Photobacterium species)
          6.  Microbial Pathogens of Animals

V.  Environmental Virology

• Return to Index