Lecture 5 JD

Question 1

Facilitation

Answer 1

facilitative or positive biotic interactions are encounters between organism that benefits at least one of the participants and cause harm to neither

Question 2

What are the two types of facilitation?

Answer 2

• commensalism
• mutualism

Question 3

What is commensalism?

Answer 3

an association between two organisms in which one benefits and the other derives neither benefit nor harm

Question 4

What are the 3 types of commensalism?

Answer 4

• phoresy
• inquilinism
• metabiosis

Question 5

Phoresy

Answer 5

involves animal attaching to another animal exclusively for transport
- e.g. sloth moths are found in fur of sloths as the sloths provide transport to the moths

Question 6

Inquilinism

Answer 6

an association between members of two different species in which one, the inquiline, lives commensally on or in the other, the host, or inside the hosts home

Question 7

Metabiosis

Answer 7

a form of commensalism in which one organism creates or prepares a suitable environment for another

Question 8

What is mutualism?

Answer 8

a relationship in which organisms of different species interact to their mutual benefit (usually involves the direct exchange of goods or services)

Question 9

What are the 4 types of mutualism?

Answer 9

• defensive
• resource-based
• dispersive
• symbiosis

Question 10

Defensive

Answer 10

one species provides protection from predators

Question 11

Resource-based

Answer 11

both species supply resources (food) to each other

Question 12

Dispersive

Answer 12

interactions in which species receives food in return for transporting the pollen or seeds of its partner

Question 13

Symbiosis

Answer 13

an intimate association between two species typically to the advantage of both. often a physically close and long-term biological interaction

Question 14

Example of symbiosis

Answer 14

lichens
- nutritionally specialised fungi (the mycobiont component) that have escaped from their normal way of life into a mutualistic association with a photobiont

Question 15

What is the main photobiont of lichens and what does it provide?

Answer 15

in 90% of lichens, the photobiont is an alga, and it provides carbon compounds to the mycobiont through photosynthesis

Question 16

What is another photobiont of lichens and what does it provide?

Answer 16

in some cases the photobiont is a cyanobacterium which may provide fixed nitrogen to thee association

Question 17

Mycorrhizae

Answer 17

plants and fungi develop mutually beneficial associations in the soil. they are often essential to the survival of the host plant (obligate vs facultative)

Question 18

Mutualistic mycorrhizal associations between fungi and plants

Answer 18

vascular plants provide carbohydrate energy to fungi (as they have no chloroplasts) in return, fungi forage for trace elements and essential nutrients throughout nearby soil. the exchange occurs at the interface (which is often complex and extensive) between the two organisms.

Question 19

What are 2 dominant types of mycorrhizae?

Answer 19

• endomycorrhizae
• ectomycorrhizae (EM)

Question 20

Endomycorrhizae

Answer 20

• vesicular arbuscular mycorrhizae (VAM)
• VAM mutualisms are present in 80% of angiosperm plants
• they fungal hyphae penetrate the host plant tissue, forming two kinds of structures: vesicles and arbuscules

Question 21

What do vesicles play a role in?

Answer 21

storage

Question 22

What do arbuscules facilitate?

Answer 22

the transfer of nutrients between the mutualist partners and comprise a complex dual-membrane between hyphae and the plant cell

Question 23

Ectomycorrhizae (EM)

Answer 23

ectomycorrhizal fungal hyphae do not form any structures within the host tissue but instead penetrate between the cells to form a Hartig net, which are enclosed in a mantle or fungal sheath, which surrounds thee growing root tip