Community Ecology

Community Ecology - the study of all the organisms in a given area at a given time. Fig 38.8b and 38.8c

Interspecific Interactions

predation

+

-

mutualism

+

+

commensalism

+

0

parasitism

+

-

competition

-

-

Competition

     Limiting factor

     Interspecific competition

Competitive exclusion Fig 38.10

 

The Niche - Image and Fig. 38.9

     Realized niche
     Fundamental niche

 

Resource partitioning - Fig 38.11

     Character displacement - Image

Symbiosis - Three Major Kinds of Relationships

Coevolution

Mutualism: both participants benefit
-- Microorganisms in digestive tracts of herbivores

-- Mycorrhizae = fungus + plant root - Image
-- Nitrogen-fixing bacteria in nodules on the roots of legumes (Image)
-- Flowering plants + pollinators  Fig 38.13

-- Some species of acacia + ants - Fig 38.15

 

Parasitism: one partner benefits (parasite), other is harmed (host) Fig. 38.16a.

       endoparasites
       ectoparasites

       parasitoids

       nest parasites

 

Commensalism: one partner benefits, other unaffected

-- Clownfish and sea anemone Fig 38.17 - The movie
-- Oxpeckers and African cape buffalo Fig 38.18

Predator-Prey Interactions - A predator in action and Fig 38.20 - may be cyclic in nature. Fig. 38.21

Predators may have special features for detection and acquisition of prey - sight, hearing, smell, speed, claws, teeth, tolerance of chemicals

    Plant Defenses

Morphological defenses
-- Thorns and spines
-- Glandular hairs
-- Deposition of crystals in plant's tissues
Chemical defenses
-- Chemical compounds

     Defenses in Animals

Speed Fig 38.19

Claws

Quills

Chemicals

Cryptic coloration - Image and Deceptive coloration

Aposematic coloration - Image
Mimicry

*Batesian mimicry - Fig 38.27
-- Unprotected species resemble protected ones
-- Harmful specimen is the model
-- Harmless specimen is the mimic
*Muellerian mimicry - Fig 38.28

Community Structure

Species diversity - Image

species richness
relative abundance of species

Dominant and Keystone Species - Image and Image and Fig 38.22

Ecological succession, disturbance and non-equilibrium