BIOL1003 Lecture Notes - Lecture 5: Intermediate Disturbance Hypothesis, Atlantic Menhaden, Keystone Species
BIOL1003: Module 4 – Ecology
Lecture 5 – Specialists/Generalists, Disturbance, Keystone Species and Interactions
Specialists and generalists
• Specialist - less resilient to disturbances
• Competitive exclusions - a competitive advantage, will eventuate in the suess… ad
extinction of the other species (can be on a local scale)
Community ecology
• Competition
o Resource partitioning
• Same habitat, different times
o Character displacement
• Very similar organisms become different over years to better fit their realised
niche
o Competitive exclusion
Disturbance
• Limits the availability of resources
• Coping with disturbances
o Specialist less resilient
o Maximal disturbance vs no disturbance
o No disturbance
• Lower biodiversity
o Maximal disturbance
• Frequently occurring, you get extinction
o Intermediate disturbance
• Balance between the other 2
• Areas with this tend to have the highest biodiversity
• Does’t result i etitio, does’t result i opetitive elusio (take over
one species)
• "Intermediate disturbance hypothesis"
• "Intermediate disturbance hypothesis"
o Diversity will be highest when interferences prevents completive exclusion, but it of low
enough intensity or frequency to allow many species to proper
o The disturbance may be due to interaction with the environment(abiotic) or other
species (biotic).
• Types
o Global warming
o Flood
o Introduction of new species
o Disease
o Logging
o Habitat fragmentation (roads)
o Natural disasters - fire, storm, cyclones
Keystone species
• Are defined by having the largest number of interactions within their ecosystems
o Not the top predator
o Or the biggest
o Starfish - if you take it out, the biodiversity oin the area will decreases
o There are lists of keystone species - need to look at definition
o Atlantic menhaden - oil production, pet food, etc (not for eating)
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