4.2 - What Shapes An Ecosystem?

• • Abiotic Factors: climate, natural disasters, natural resources
  • Ex: Soil mineral content, pH, and structure limit plant species and the animals that feed on them
• • Biotic Factors: the living factors in an ecosystem like plant, animals, bacteria, and fungus - these organisms interact and affect each others survival
  • Habitat: the places in an ecosystem where an organism lives
  • Niche: the role a species plays in an ecosystem
  • type of food it eats
  • where it lives and reproduces
  • relationships w/ other species
• Biotic Factors (1)

  • Competition:
  • Occurs when organisms of the same or of different species attempt to use the same resources at the same time
  • No two species can occupy the same niche
• Keystone Species: A species that helps hold an ecosystem together and define the characteristics of an ecosystem

  • Without its keystone species, the ecosystem would be dramatically different or may not be able to adapt to environmental changes - fall apart
  • No other species in the ecosystem can fill the niche of the keystone species
• Community Interactions

  • Predator/Prey: one organism hunts and consumes another organism
  • Ex: Lion and antelope
  • Symbiotic Relationships: two organisms live in direct contact with one another -> three types = mutualism, parasitism, and commensalism
• Symbiotic Relationships

  • Mutualism: both species benefit from the relationship (+/+)
  • Ex: birds on a water buffalo, clown fish & anemone
  • Parasitism: parasite lives in/on a host and takes its nutrients (+/-)
  • Ex: mistletoe on trees, tapeworms
  • Commensalism = One organism benefits and other is unaffected (+/0)
  • Ex: shark & remora
• Ecological Sucession

  • Ecosystems are constantly changing
  • Sucession is when one community replaces another as a result of changing biotic and abiotic factors
  • Two types of Sucession: primary and secondary
• Primary sucession

  • A new community forms in an area of bare rock that has no soil
  • pioneer species - the first species in an ecosystem that helps to break down rock into soil
  • Over hundreds of years, the community becomes stable and no real change occurs -> climax community
• Secondary succession

  • Disturbances such as fire, flood, and building remove or kill off the organisms in the community
  • The organisms are removed but the soil remains
  • Plants and animals may return to the area in a predictable way