Functional roles within communities Flashcards
3 types of key species with highest impact on community structure?
- Dominant species
- Keystone species
- Foundation species (ecosystem engineers)
Most abundant or have the highest biomass in a community?
Dominant species
What causes a species to become dominant?
- dominant species more competitive at obtaining resources and more likely to win
- better at avoiding predation or disease
Why are invasive species so successful?
Climate change causes them to relocate and are transported to different areas
How do we measure impacts of dominant species on a community?
We remove it
How to research species removal?
- Natural experiments
- Humans removing dominant species
- Mathematical modelling
- Microcosm experiments (Petri dishes)
How do Keystone species get their name?
They lock whole structure into place, removal and community collapses. Not most abundant but strong control and how it interacts
Origin of concept of keystone species
- 1960’s
- still relevant
- Robert Paine
Removing the keystone species does what…?
Species richness falls rapidly
Keystone predator =
Massive effect despite not being abundant
What is an ecosystem engineer or foundation species?
Animals which physically alter their environment
Example of ecosystem engineer
American beaver
Example of keystone species
Sea otter
What describes community organisation?
SImple models or the regulatory relationship between trophic levels
What is meant by bottom-up control?
Communities only change in lower trophic levels
Increase in vegetation leads to more herbivores
Changes in nutrients drives trophic structure
Cascades up through food chain
what is meant by top-down control?
Communities only change via changed in upper trophic levels
Changes in predator numbers effects lower trophic levels
Indirect effects from high level community to a lower level
Bottom up and top down are extreme, what is normal?
Most communities interactions between trophic levels is reciprocal or direct of control may change over time and often can be both
Ecosystems are influenced by what human management measures?
- Agricultural landscapes
- National parks
- Fisheries
