3 - Community Ecology Flashcards
(29 cards)
Classical biodiversity examples
quadrats, walks, traps
What are the benefits of classical biodiversity assessment techniques
Relatively inexpensive
Direct, observable data collection
Good for large and visible organisms
What are the drawbacks of classical biodiversity assessment techniques
Labour-intensive and time-consuming
May miss cryptic, rare, or nocturnal species
Potential disturbance to habitat and species
Molecular biodiversity Assessment example
eDNA
What are the benefits of molecular biodiversity assessment techniques
Detect unculturable, rare, hidden organisms
High sensitivity and massive data generation
Standard method in microbiome studies (e.g., 16S rRNA barcoding)
What are the drawbacks of molecular biodiversity assessment techniques
Requires expensive equipment and expertise
Risk of contamination (false positives)
Difficult to distinguish live vs dead organisms
What is Alpha Diversity
Number of species in a site
Measures species richness and evenness at a local scale
What is Beta Diversity
Variation in species composition between sites
High beta diversity = sites have very different species assemblages
What is Gamma Diversity
Number of species across an entire landscape
Combines both alpha and beta diversity
Key interpretations for Alpha, Beta, and Gamma Diversity in conservation
High alpha: Conserve individual sites
High beta: Conserve multiple distinct sites
Gamma: Represents overall regional biodiversity
What are trophic (consumptive) interactions? Give examples
Involves energy transfer (e.g., herbivory, predation, parasitism, decomposition)
Represented in food webs
Can be specialist or generalist feeding strategies
What are non-trophic (non-consumptive) interactions? Give examples
No direct energy exchange
Includes symbioses, mutualisms, mimicry, allelopathy, environmental modification
Examples: Coral reefs (substrate creation), beaver dams (river modification)
Define an ecosystem engineer
Species that physically modify the environment
Ecosystem engineer example
Beavers (wetlands), earthworms (soil aeration), coral (reef structure)
Define a keystone species
Species with disproportionately large community impact
Keystone species examples
Starfish (Pisaster) maintaining diversity by preying on dominants
Sea otters maintaining kelp forests by controlling sea urchins
How are keystone species identified
Removal experiments: Collapse or major shift in community structure
Regulation of competitive dynamics among species
What is the Dispersal Filter in community formation
Determines which species reach a location
Example: Oceanic islands = fewer species due to isolation
What is the Environmental Filter in community formation
Determines which species survive local conditions
Species must fit within their fundamental niche
What is the Ecological Filter in community formation
Determines coexistence based on biotic interactions (e.g., competition, predation)
Species fit within their realised niche
What is the predictability of community formation
“Priority effects”: Order of arrival influences final community
Succession stages are somewhat predictable, but exact composition is often not
How does keystone species restoration benefit ecosystems (Give an example)
Restores ecosystem function
Example: Sea otter reintroduction restores kelp forests by controlling sea urchins
What happens at critical thresholds for species loss
Communities may collapse if functional groups are lost
Functional redundancy can buffer loss, but not the loss of key groups
What is assisted restoration
Active management is sometimes needed, especially under high herbivory or degraded ecosystems
