CH 16: Mutualism

What is a mutualism?

An interaction between two species that provides fitness benefits to both.

In the context of mutualism, what is a generalist species?

A species that interacts with many other species.

In the context of mutualism, what is a specialist species?

A species that interacts with one or a few other species.

Define 'obligate mutualists'.

Two species that provide fitness benefits to each other and require each other to persist.

Define 'facultative mutualists'.

Two species that provide fitness benefits to each other, but whose interactions are not critical to the persistence of either species.

What type of mutualism exists between a tree shrew and a pitcher plant?

The tree shrew receives nectar and the plant receives nitrogen from the shrew's faeces, which it uses as a 'bathroom'.

_ are a type of fungus that surround plant roots and help plants obtain water and minerals.

Mycorrhizal fungi

What are the three main types of mycorrhizal fungi mentioned in the source material?

Endomycorrhizal fungi, ectomycorrhizal fungi, and endophytic fungi.

In the mutualism between legumes and Rhizobium bacteria, what does the plant provide for the bacteria?

The plant provides the bacteria with sugars from photosynthesis and a root nodule in which to grow.

In the mutualism between legumes and Rhizobium bacteria, what do the bacteria provide for the plant?

The bacteria convert atmospheric nitrogen into ammonia, a form of nitrogen the plant can use.

What type of mutualism is exemplified by the alpheid shrimp and the pink bar goby?

A habitat mutualism.

Describe the habitat mutualism between the alpheid shrimp and the pink bar goby.

The alpheid shrimp digs a burrow for both to live in, and the goby acts as a lookout for predators.

What is one benefit that mutualistic ants provide to acacia trees, besides protection from herbivores?

The ants can cause a reduction in harmful bacteria on the acacia plant.

What service does the cleaner wrasse provide to the yellowfin goatfish?

The cleaner wrasse removes parasites from the goatfish's body.

What is the mutualistic relationship between oxpeckers and large mammals?

Oxpeckers eat ticks and other parasites off the mammals' bodies, providing food for the bird and pest removal for the mammal.

What is the specific name of the bat mentioned as an example of a pollinator?

The lesser long-nosed bat.

Describe the mutualism between the yucca plant and the yucca moth.

The yucca moth pollinates the yucca plant, and the plant serves as a food source for the moth's larvae.

What are elaiosomes?

Lipid and protein-rich tissues attached to seeds that attract ants.

What benefit do ants provide to plants by eating elaiosomes?

The ants act as seed dispersers by carrying the seeds back to their nests.

Under what circumstance might a mutualistic relationship change?

A mutualism can change to predation or parasitism when environmental conditions change.

What species pairing is given as an example of a mutualism that can switch to parasitism?

The cleaner wrasse and the damselfish.

How did the wild onion demonstrate that mutualists can favour more beneficial partners?

The plant allocated more products of photosynthesis to the more beneficial species of mycorrhizal fungus in its roots.

What invasive plant is mentioned as an example of one that can disrupt existing mutualisms?

Garlic mustard.

Beyond individual species, what three larger-scale ecological structures can mutualisms affect?

Species distributions, communities, and ecosystems.

What was the observed effect of fencing off deer from acacia trees on the mutualistic ant species?

The acacia offered fewer benefits, causing one ant species to become 'withdrawn' while the other increased its presence.

What is the ecosystem-level effect of increasing the species diversity of mycorrhizal fungi?

It has positive effects on the plants within the ecosystem.

What is a 'substitute mutualist' in a conservation context?

An introduced species that takes over the ecological role of a missing or extinct mutualist partner.

What animal was introduced to an island in Mauritius to act as a substitute mutualist?

The Aldabra tortoise.

What was the conservation goal of introducing Aldabra tortoises to Mauritius?

To act as a seed disperser for a critically endangered population of ebony trees.

The interaction between coral and _ is a classic example of mutualism.

zooxanthellae