BI303 - Section 2 Lecture 5

What is a tropic level?

A position in a food chain

How do predator-prey relations affect ecosystems?

They control abundance and biomass of species.

What factors control baseline ecosystem productivity?

Climate, latitude and soil

What influences trophic structures and biomass distribution in ecosystems?

Predator behaviour and predator-prey interactions

What are antagonistic biotic interactions?

Interactions where one organism benefits at the expense of another.
Competition and predation.

What is intrapspecific competition?

Competition among individuals of the same species

What is interspecific competition?

Competiton among individuals of different species

What is herbivory?

Consumption of plants by animals

What is predation?

One organism consuming another for food

What is parasitism?

One organism benefits and the other is harmed

What are positive biotic interactions?

Encounters that benefit at least one participant.
Cause harm to neither participant.

What is commensalism?

One organism benefits, but the other is unaffected

What is phoresy?

One animal attaches to another for transport

How do sloth moths benefit from sloths?

They use them for transport and habitat

What is inquilinism?

Living commensally on or in another organism

What is metabiosis?

One organism prepares an environment for another

How do hermit crabs use gastropod shells?

For shelter and protection

What are the types of positive biotic interactions?

Faciliation.
Commensalism.
Mutualism.

What is mutualism?

Interaction benefiting both species.

What is defensive mutualism?

Mutualism providing protection to one partner

How do leaf cutter ants exhibit defensive mutualism?

They avoid parasitism by foraging at night

What is resource-based mutualism?

Mutualism involving exchange of resources

How do leaf cutter ants and fungi interact?

Ants cultivate fungi for food and nutrition

What role do fungi play for leaf cutter ants?

They provide nutrition for ant larvae

What are dispersive mutualisms?

Interactions where species transport pollen or seeds

What are the types of mutualism?

Defensive.
Resource-based.
Dispersive.

What is symbiosis?

An intimate association between two species

How do lichens form a mutualistic association?

Fungi and algae or cyanobacteria work together

What is the role of mycorrhizae in plant survival?

They help plants obtain essential nutrients

What do vascular plants provide to fungi in mychorrhizal associations?

Carbohydrate energy

What are the two dominant kinds of mycorrhizae?

Endomycorrhizae and ectomycorrhizae

What structrues do CAM mutualisms form in host plants?

Vesicles and arbuscules

What do ectomycorrhizal fungal hyphae form around root tips?

A mantle or fungal sheath

What is the summary of antagonistic and positive biotic interactions?

Antagonistic - one benefits at the other expense.
Positive - exchange resources for mutual benefit.
Symbioisis - intimate association for mutual advantage.

What is the role of mycorrhizae in land plants?

Essential for nutrient acquisition