Nonpredatory Interactions

• Competition -> interaction has negative effects on both individuals
• Density dependent competition -> amount of competition is related to the density of competitors
• What's an example of density dependent comp?

  comp for food becomes more intense as number of individual increases
• density dependent comp can negatively affect growth and reproduction rates and can lead to resource partitioning and specialization
• What are the two types of competition?

  Exploitative and interference
• Exploitative (scramble) comp

  • as resources decline each individual gets less (all equally affected)
  • does not involve direct interactions between individuals
  • common when populations sizes are large and everyone is trying to get as much resources as possible
• Interference Comp

  • individuals directly interfere with one another to get resources (some get more then others)
  • occurs when resources are haphazardly distributed
• comp can impact spatial patterns in species distribution
• species can avoid competition by specializing
• mutualism -> both species have a positive effect on each other
• facilitation -> unidirectional positive effect of one species on another
• mutualism is not common in freshwater ecosystems