Study%20of%20Communities

1
Study of Communities
2
Communities

• group of interacting organisms sharing an
  environment

3
Biodiversity

• variation of life forms or species within a given
  community, ecosystem, biome, or for the entire
  Earth
• often used as a measure of the health of
  biological systems
• biodiversity found on Earth today consists of
  many millions of distinct biological species,
  which is the product of nearly 3.5 billion years
  of evolution

4
Measuring Biodiversity of a Community

• Number of species which are in a community
• Relative abundance of each species, number of
  individuals of one species compared to the total
  number of individuals in the community

5
Biodiversity of a community

• Is high when
• ?Number of species is high
• ?Relative abundance of different species is
  similar

6
Interactions between individuals of a community

• Competition
• Predation
• Mutlualism
• commensalism

7
Competition

• Interaction between individuals fighting for a
  resource in the environment
• Two types intraspecific and interspecific
• Intraspecific- between individuals of the same
  species
• Interspecific- between individuals of different
  species

8
Predation

• Interaction between two species where one
  individual consumes another individual
• Predator- one that eats
• Prey- one that gets eaten
• Parasitism is a form of predation involving a
  parasite and a host
• The parasite eats the host. The parasite has a
  benefit, the host does not.

9
Mutualism

• Interaction between two individuals where both
  individuals receive some benefit
• Ex. Sea anemone and clown fish
• Flowers and bees

10
Commensalism

• Interaction between individuals where one
  individual experiences and advantage but the
  other individual experiences no advantage or
  disadvantage
• Ex birds nesting in trees or using abandoned nests

11
Effect of interactions between populations on
their densities
Type of Interaction Effect on Population A Effect on Population B
Competition - -
Predation and Parasitism -
Mutualism
Commensalism 0