Chapter 15 - Mutualism and Commensalism

Fungus growing ants started cultivating _____ for food for at least ____ _______ years before the first human farmers

fungi, 50 million

What two things do fungi do deter insect herbivores

they digest and detoxify chemicals that the plant uses

what type of interaction is the digestion and detoxification from fungi

positive interaction

what is symbiosis

when two species live in close physical contact with each other

What are the three relationships of symbioses?

parasitism (±)

commensalism (+/0)

mutualism (+/+)

is commensalism considered a positive interaction

yes, it is any interaction where one or both species benefits and NEITHER is HARMED

In mutualism, there is a cost to one or both partners (sacrificial or altruistic), but…

the net effect is positive

commensalism

one benefits, one gains nothing but doesn’t lose anything either

What are the benefits of positive interactions

food

shelter

transport

like altruism, for each species in a mutualistic relationship, the benefits are _____ than the costs

greater

What is the most important symbiosis on earth

mycorrhiza

mycorrhizal fungi are a group of what kind of fungi

network-forming soil fungi

What is the relationship of mycorrhiza

they have symbiotic associations with plants

mycorrhizal associations are extremely _______ in the plant kingdom

abundant

Over _____% of plant species form mycorrhizal associations

80

mycorrhiza fungi have altered evolutionary history - T/F

true

Associations with Mycorrhiza have shaped life on earth more than

400 million years ago

what are the underground economics of plants and mycorrhizae?

strike compromises

resolve trade-offs

deploy trading strategies

what are the four types of mycorrhizal fungi?

arbuscular

ectomycorrhizal

orchid

ericoid

plants that association with arbuscular fungi make up around how much of global plant biomass

70% of global plant biomass

ectomycorrhizal lifestyle has evolved independently more than

70 different times

17,000 species of orchids rely on specialized fungal partnerships for (orchid mycorrhizal)

nutrients

In ectomycorrhizae (ECM), fungus grows between _____ ____ and forms a ______ AROUND the root

root cells, mantle

in arbuscular mycorrhizae (AMF), it ________ the cell walls of some root cells and forms an ________

penetrates, arbuscule

What is an arbuscule

a branched network fromed by AMF

ECM (ecto) are found in _______ regions and AMF(arbuscular) are found in ______ regions

temperate, tropical

What does coral provide for algae in their mutualistic relationship (3 things)?

home

nutrients (nitrogen and phosphorous)

access to sunlight

what does algae provide coral back with

carbohydrates produced by photosynthesis

Herbivores depend on bacteria and protists in their gut for

metabolizing cellulose

Some positive interactions are OBLIGATE, meaning

some species completely rely on one another for survival, it just so happens that their relationship is beneficial for each other

Some positive interactions are facultative, like with trillium glandforum. while seeds are still going to be dispersed, deer are able to

spread the seeds much farther than other means of transport

What are basic examples of commensalism?

lichens growing on trees

bacteria on human skin

species using kelp forest for shelter only

What is the relative neighbor effect (RNE)

its the observance of the growth of a species based on the presence and removal of a neighbor

growth w/ neighbor - growth w/o neighbor

in the study from the lecture what was the RNE at high elevation and low elevation sites?

high elevation - positive RNE (neighbors were positive)

low elevation - low RNE (neighbors were negative)

this type of mutualism is centered around the acquisition of energy or nutrients from a partner

trophic mutualism

this type of mutualism is centered around providing shelter, living space, or a favorable habitat

Habitat mutualism

the pistol shrimp digging burrows to share with goby fish is what type of mutualism

habitat mutualism

In an experiment by Kiers et al, the Medicago truncatula plant would allocate more carbohydrates to mycorrhizal fungi that

provided them with higher concentrations of phosphorous ( shows that they have learned to give equal trade-offs and awards for the effort that is put in)

What is cheating in the context of symbiosis?

individuals that increase offspring production by overexploiting their mutualistic partner

What occurs with the Yucca and Yucca moth with cheating?

the female moth collects pollen in one yuca and lays eggs in another. The retention of flowers with 0-6 eggs (62%) is a LOT higher than those with 9-12 eggs (11% retention)

What is an interaction that can have a bad ecological consequence?

ants that feed on the nectar and high-protein beltian bodies of a tree will patrol it 24 hours a day, but its attacks are really aggressive and can even destroy plant competitors

mutualism and commensalism influences

growth

survival

reproduction

community interaction

some interactions can also only be positive based on certain conditions. what were the interactions of cattails (Typha) with myosotis in low soil temps and high soil temps

low - typha increases growth of myosotis by aerating soil

high - typha was competitor and decreases growth of myosotis due to limited ability of transporting oxygen due to lack of aeration from wetland soils.

what are two “checks and balances” recognized in the yucca and yucca moth example, overall making sure that one partner is not over-exploited?

1. yucca plants have a threshold for the amount of moth eggs - the cost of seed predation CANNOT outweigh the benefit of the pollination

2. Although the moth is laying a lot of eggs to maximize its reproductive success, the plant’s ability to abort flowers limits this behavior and prevents a huge population.