INVASION ECOLOGY

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INVASION ECOLOGY

• COMMUNITY ECOLOGY

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What is Community ecology?

• Study of how organisms and species interact.
• Who eats who?
• How do individuals and species compete?
• How do disturbances affect communities?

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Who eats Who?

• Predators
• Herbivores
• Parasites
• Pathogens

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Who eats who? Why is it important?

• Maintains biodiversity
• Herbivores keep purple loosestrife at about 5 in
  European wetlands.
• Thats Biological Control

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Biological Control

• Definition The introduction of a specialized
  species to control another species.
• Biological control will not wipe out a species.
• Can reduce population to limit its impact.

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Biological Control

• Effective biological control must be
  HOST-SPECIFIC.
• Feeds on only one or a very few species.

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Biological control Using Insects

• Identify insects eating the plant in its native
  habitat.
• Identify the host specific insects.
• Test effects of insects on plants growth.
• Select the most useful insects.
• Wide distribution
• Large effect

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Biological control Using Insects

• Identify test plants.
• Will other important plants at risk?
• Test for host specificity.
• Get government approval
• Test potential of your biological control.
• Will the control survive?
• Can it be easily raised?

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Biological control Using Insects

• Release and monitor.
• Evaluate effectiveness.
• Long-term monitoring.

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Food Chains and Food Webs
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Food Webs
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Competition

• Competition results in reduced growth of one of
  the competitors

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Species Types

• Species Types
• Native Species
• Nonnative AKA Exotic AKA Alien species
• Indicator Species
• Earlier warning of ecosystem damage

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Species types

• Keystone Species
• most important species.
• Examples
• Pollinators, seed dispersers
• Habitats modifiers
• Top predators
• Nutrient cyclers

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Species Interaction

• Interspecific competition
• Predation
• Parasitism
• Mutualism
• commensalism

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Competitive Exclusion Principle

• The niches of two species cannot significantly
  overlap for long
• One of the species will be eliminated

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Avoidance of competition

• Similar species tend to use slightly different
  niches in order to reduce competition
• Resource partitioning or Character displacement.
• Divide the resources or Change physically or
  behaviorally

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Resource Partitioning
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Ecological Succession

• Primary Succession
• Starts with no soil
• Pioneer species lichen, moss - start forming
  soil
• Grasses herbs
• Low shrubbery

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Ecological Succession

• Small trees requiring lots of sun
• Large shade resistant trees
• This stage is long lasting Climax Community

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Ecological Succession

• Secondary Succession
• Starts with soil in disturbed areas
• Caused by a disturbance
• Fire
• volcano
• Road building

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Ecological Succession

• Facilitation Early species make an areas
  suitable for other species. (Ex soil building)
• Inhibition Early species hinder other species.
  (Ex. Release of toxins)
• Tolerance later species are generally
  unaffected by other plants

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Human Disturbances

• Invasive species can not be understood unless you
  understand community ecology.