Species Interactions 2

Detritivores

organisms that feed on nonliving organic matter and fragment dead material

Decomposers

Organisms that perform crucial mineralization steps

Varying litter mesh bag size

proxy of organic material (cotton strips)

How to measure contribution of micro vs. vacro-organisms to decomposition

Introduction of top predators like wolves

scavenging opportunities may increase with:

Parasites

dominates food web links

Mutualism

Net benefit for both partners

parasitism

Negative effect for host and positive for parasite

Parasitism to commensalism to mutualism

mutualism-parasitism continuum

Facultative mutualism

interactions where the participants can live without their mutualistic partners

Obligate mutualism

interactions where the participants are dependent on the mutualistic relationship for survival

Symbiotic relationships

organisms that live in close proximity to each other

Nonsymbiotic relationships

organisms that do not live in close proximity to each other

Mutualism between corals and unicellular algae called zooxanthellae.

• zooxanthellae receive nutrients from corals

• corals receive organic compounds synthesized by zoxanthellae during photosynthesis

coral reefs mutualism example:

80%

how much of plant pollination is by animals?

Ants and bullshorn acacia

• Acacia shoots without ants have much larger number of herbivorous insects

mutualism as protection example:

mycorrhizal fungi may improve ability of plants to extract soil water

mycorrhizal fungi supply inorganic nutrients to plants in exchange for carbohydrates

Plant roots and mycorrhizal fungi interaction

parasite

organism that grows, feeds, and is sheltered in or on another organisms and provides no benefit to survival of the host

Parasitoid

Parasite that ultimately sterilizes or kills the host to complete their life cycle

wasps

mistletoe

Parasitoid examples:

Cricket with parasitic worm (makes it jump in water)

behavioural parasite change example