Topic 8: Community Ecology Flashcards
What is predation?
An interaction where one species (predator) feeds upon another (prey).
What are 3 main types of predators?
- Herbivores.
- Carnivores.
- Cannibals.
What are mobile animal grazers?
Mobile animals that feed on stationary animals.
What are monophagous predators?
Predators that only feed on one type of prey.
What type of predator feeds on plants or parts of plants?
Herbivores.
What type of predator feeds on animals?
Carnivores.
What type of predator feeds on its own species?
Cannibals.
What direction is the interaction between prey and predator?
Two-way interaction.
Prey population size may control predators, and predator population size may control prey.
What are 2 successful examples of biological predation controls?
Cactoblastis moth controlling Prickly Pear in QLD.
South American Weevil controlling water hyacinth.
What are two unsuccessful examples of biological predation controls?
Cane toads to control sugar cane beetles in QLD.
Stoats and weasels to control rabbits in NZ.
Why aren’t 2 species predator-prey cycles common?
- Most systems contain >2 species.
- Environmental conditions are not constant (e.g. boom-and-bust cycles).
- Other factors influence population size.
The level of predation related to the availability of prey is what type of regulation?
Density-dependent regulation.
What predators are best for biological control?
- Specialised monophagous predators.
- Predators that virtually eliminated prey, then become scarce but not extinct.
When does predation control fail?
When the predators have a broad dietary range.
What are 6 types of herbivores?
- Frugivores.
- Granivores.
- Folivores.
- Grazers and browsers.
- Nectarivores.
- Fungivores (mycophagy).
What are the 2 categories of herbivore-plant systems.
- Interactive herbivore systems.
- Non-interactive herbivore systems.
What is an interactive herbivore system?
A system where herbivores influence biomass growth rate and subsequent vegetative life.
e.g. grazer eats the plant right down or rips the plant out
What is a non-interactive herbivore system?
A system where there is no relationship between herbivore population density and subsequent condition of vegetation.
e.g. birds eat the seeds or nectar of a plant
What are ungulates?
Hoofed mammals, especially herbivores.
How can herbivores change the condition of vegetation in an interactive system?
- Reducing total plant biomass.
- Changing vegetation structure.
- Changing vegetation composition through selective grazing.
What is batesian mimicry?
When a palatable or harmless species mimics an unpalatable or harmful species.
What is mullerian mimicry?
When two or more unpalatable species represent each other.
What 2 types of defences do plants have?
- Physical defences. Including tough leaves, waxy cuticles, spines, and hairs.
- Chemical defences. Including toxic compounds (tannins, alkaloids) and unpalatable compounds.
How do herbivores overcome plant defences?
- By being a generalist feeder and eating a variety of plants.
- By being a specialist feeder with mechanisms for avoiding the plant’s defences.
What is the consequence of strong selection pressure for both predator and prey to become more efficient at survival?
The predator-prey arms race.
What are predators that influence the overall structure of their community?
Keystone predators.
How do keystone predators perform their ecological role?
Through controlling the abundance of dominant organisms that may otherwise outcompete other species, overgraze the community and prey heavily on lower trophic levels.
What is a keystone species?
An organism that helps hold the community/ecosystem together.
What type of competition occurs between members of the same species?
Intraspecific competition.
What type of competition occurs between members of different species?
Interspecific competition.
What can be caused by the exploitation or depletion of keystone predators?
A trophic cascade.
What type of competition occurs when organisms use common resources that are in short supply?
Exploitative competition.
What type of competition occurs when organisms seeking a resource prevent others from accessing it?
Interference competition.
What is a niche?
All the environmental factors required for a species’ existence.
What is the total range within which a species could potentially occur?
Its fundamental niche.
What is the actual range within which a species occurs?
Its realised niche.
What has the potential to occur in niche overlap?
Competition.
What are the 3 outcomes of competition?
- Competitive exclusion.
- Resource partitioning.
- Character displacement.
What is competitive exclusion?
One species outcompeting another and excluding the lesser competitor.
What is resource partitioning?
Species partition a resource amongst the different species to reduce competition.
What is character displacement?
Competition between species driving divergent evolution, causing morphological changes.
What populations contain species that live apart?
Allopatric populations.
What populations contain species that live together?
Sympatric populations.
What are the 4 key properties of communities?
- Diversity.
- Prevalent form of vegetation.
- Stability.
- Trophic structure.
