Lecture 9 community ecolgy: Mutualism

Question 1

Define Mutualism, Symbiosis.

Answer 1

Mutualism: Two species being benefitted of each other

Symbiosis: Species living together

Question 2

Are all mutualisms symbiotic?

Answer 2

Most mutualisms are but not all symbiosis.

Question 3

What does mutualism typically involve?

Answer 3

Exchanging reciprocal good and services between species

Question 4

What are three types of mutualism?

Answer 4

1.Nutritional Mutualism
2.Defensive mutualism
3. Dispersal mutualism

Question 5

What is nutritional mutualism?

Answer 5

Mutualism between legumes and nitrogen-fixing bacteria called rhizobium

Plants and mychorizzal fungi: Fungi provide phosphorous, water or other nutrients while plants reward it by giving carbohydrates

Legumes provide carbohydrates to the bacteria while the rhizobium converts Nitrogen into a form that plants can use

Question 6

What is defensive mutualism?

Answer 6

Exchange of protection, like ants and plants, cleaner fish and client fish

Usually, Ants and Plants:

Ants get extra floral nectar, while plants get security from ants against other herbivores.

Cleaner fish remove parasites and they get food.

Question 7

What is dispersal Mutualism?

Answer 7

Plants and Animal seed dispersal: Typically one moves offsprings of the other. (exchange seed dispersal for food)

Plant and Animal pollinators: Exchange gamete dispersal for food.

Question 8

What is a Lotka-Voltera model for mutualism?

Answer 8

Same as interspecific competition, but with addition for the competiton from species 2.

dN1/dt = rN1 (1 - N1/K1 + alpha12*N2/K1)

Question 9

What is invitational meltdown

Answer 9

The process coined by Simberloff and Von Holle, the process by which two non-native species facilitate one another’s spread

Question 10

What is an example between wild animals and humans
mutualims?

Answer 10

Yao people in Mozambique and the honeygiudes (indicator indicator)

Question 11

What did claire spottiswoode’s research show?

Answer 11

The probability of guidebee’s responding was higher when yao people called (Honey-hunting sound) while probability was less in human control and animal control.

Question 12

What is the problem with lotka-volterra model for mutualism?

Answer 12

Even if N1 reaches the carrying capacity, the term will never become 0, hence it says that both populations will grow exponentially, in orgy of mutual benefaction.

Question 13

What limits the population growth in mutualism?

Answer 13

1) Strong intra-specific competition

2) Third species or a predator or a competitor

3) Diminishing returns to mutualism as the population grows.

Question 14

At what size does mutualism have positive benefits?

Answer 14

When the population size is small, but not when it is big.

This is because, near carrying capacity, the population no longer grows hence no point in growth in mutualism

Question 15

What does positive feedback generate between mutualists?

Answer 15

Runway population growth

Question 16

What was the difference found in native seed dispersal ants (Aphaenogaster rudis ) and invasive ant species (Myrmica rubra) aka European fire ant?

Answer 16

The native ant species (Aphaenogaster rudis) facilitated the germination of native plant seeds while myrica rubra facilitated the germination of invasive plant species

Question 17

Which experiment showed the example of invasive meltdown?

Answer 17

The Aphaenogaster rudis ants (native) and the myrmica rubra facilitating growth of different plant species.

Question 18

What is an example of defensive mutualism?

Answer 18

Cleaner fish and client fish

Y-axis: Has gnathiids per fish
X-axis: Has reefs

cleaner fish feed on the ectoparasites of the client fish (gaining food) while client fish loose the parasites

Experimentally removing the cleaner fish from the cleaning stations (territories) that clients visit increased the number of gnathiids abundance on clients

this remained the same in 12 days, 12 hours and 24 hours

Question 19

What did Redouan Bshary’s experiment show?

Answer 19

Y axis: Change in specie diversity

X axis: Natural, experimental and combined.

Value of 0, meant no changes in the number of fish

When cleaners were removed fish diversity went down, while if they were added fish diversity went up.

In this case mutualism increases fish diversity.

Question 20

What is an example of adaptative mutualism?

Answer 20

Darwin’s orchids: (Epiphyitic orchids) from Madagascar
which was predicta, as predicted by darwin.

Question 21

Why was the orchids from Madagascar and predicta an example of evolutionary arms race?

Answer 21

Because the longer the nectar spurs orchids grew the longer the proboscis of the predicta became. (an example of evolutionary arms race or coevolution)

Question 22

How was the reciprocal adaptation studied?

Answer 22

x axis: had proboscis length and floral tube length

y axis: had nectar consumed and pollen grains deposited.

If the length in (mm) of the was longer, more proboiscus length helped in getting more nectar

More floral tube length meant more pollen grains deposited

Question 23

What does endosymbiont mean?

Answer 23

Bacteria lives within its host.

Question 24

What does vertically transmitted mean?

Answer 24

They are passed from aphids mother’s eggs to offspring’s

Question 25

Who studied the endosymbiosis of buchnera in aphids?

Answer 25

Nancy Moron

Question 26

What are the features that show buchnera has evolved with aphids?

Answer 26

Buchnera has much smaller genome than E-coli

Question 27

When do bacterias have very tiny tiny genomes?

Answer 27

When a bacteria lives in the host cell as a symbiont

(genome shrinks when bacteria lives in a host cell. mitochondrion has 1700 base pairs of codons, while human genome has around 3 billion base pairs)

Question 28

What are some theories for why endosymbionts looses genome?

Answer 28

Because it is well protected in the host cell, and other function can get out sourced.

Question 29

What is horizontal transmission?

Answer 29

Most mutualisms have to find their partners anew each generations.

Question 30

Are most interactions one-to-one in mutualisms?

Answer 30

No, they have many interactions, usually many-to-many

Question 31

What is microbiome?

Answer 31

Either all the microbes living together in a community (often in a host) or in their collective genome.

Question 32

What is a network of interaction?

Answer 32

Nodes are species, lines are interactions that occur between species.

Question 33

What makes a potential host-microbe mutualism?

Answer 33

Having the right diversity of microbiome.

Question 34

What does sequencing highly conserved genome mean?

Answer 34

slowly evolving gene, usually bacterial 16S rRNA gene

Question 35

What did Ruth Ley do?

Answer 35

Study the distribution of microbes in different specie’s guts.

Question 36

What do the dots closer together in principal components analysis in Ruth Ley’s study mean?

Answer 36

The dots are animals, and closer ones have similar microbiomes.

Question 37

What does microbiome in a gut reflect?

Answer 37

Diet, Phylogeny and morphology