1: intro

Question 1

what is the ancient greek and historical meaning of symbiosis?

Answer 1

greek: derivation meaning living together
historical: close and often long term interaction between 2 or more different biological species

Question 2

what is Anton de Bary’s definition of symbiosis and when

Answer 2

the (intimate) living together of unlike organisms 1879

Question 3

what is mutualism?

Answer 3

symbiosis where both partners derive a fitness benefit

Question 4

what is commensalism?

Answer 4

symbiosis where one partner derives fitness benefit at no fitness cost to the other

Question 5

what is parasitism?

Answer 5

symbiosis where one partner derives fitness benefit at fitness cost to the other

Question 6

what do some such as prof. angela douglas argue about the symbiosis model and is this correct?

Answer 6

split into parasitic OR commensal OR mutualistic
- assumes benefits and costs symmetrical
- but sometimes one partner may benefit more than the other
NOT CORRECT

Question 7

what is symbiosis considered and what happens at the point where parasitic and mutualistic symbiosis meet?

Answer 7

continuum

commensalism at this point (one partner benefits at no cost to the other)

Question 8

what is temporally dynamic mutualism?

Answer 8

organisms can have different symbiotic associations in a single lifetime

Question 9

how does orchid mycorrhizal symbiosis work?

Answer 9

roots take up water and nutrients and outsource to fungus to cover a wider area of soil to forage nutrients and feed them to the plant root system

Question 10

what % of plants only exist due to symbiotic relationship with fungus?

Answer 10

roughly 90%

Question 11

how may you measure how much C a plant gave to a symbiont?

Answer 11

expose to radioactive CO2 to see the network of fungus with the radiation

Question 12

• why may mycorrhizal plants grow larger than other plants?
• what stress can they survive?
• what can enhance growth rate?

Answer 12

• can access more N and P
• stress of nickel added
• C enhances growth as enhances P

Question 13

typically how many seeds are produced by an orchid plant? and what are they known as?

Answer 13

100,000 per plant (small so cant give seeds resources to germinate on their own)
- dust seed : 4-16 cells

Question 14

give 6 points and stages on the unusual orchid lifecycle

Answer 14

• symbiotic germination: cause fungus to grow towards plant and invade cells causing germination
• fungus dependent seedlings: protocorms are underground for years taking C and nutrients from fungus until can germinate
• life stage dependent trophic switch: heterotrophic–> autotrophic
  mutualistic symbiosis as adult, parasitic as seedling
• continuum of symbiosis
• some adults have chlorophyll others don’t
• some adults may become parasites

Question 15

Martin et al 2012 abstract and intro? (5)

Answer 15

• De Bary definition widely used in textbooks
• 85% textbooks studied defined symbiotic interactions as mutualism, commensalism, parasitism
• predator/prey and herbivore/carnivore considered organisms
• confusion and controversy towards symbiosis
• authors tried to broaden De Barys definition

Question 16

Martin et al 2012 results and discussion? ()

Answer 16

• some include parasitoidism (intimate) in De Barys definition (organism spends most of life history attached to/within host sterilising/killing it)
• all books studied discussed competition, grazing, predation, parasitism, commensalism, mutualism
• intimacy and constancy required
  all species interactions ectosymbiotic but only mutualism, commensalism, parasitism, parasitoidism endosymbiotic
• antagonism includes any negative species interactions
• facilitation: species can have positive effects on survival and reproduction of other species
• predation can be symbiotic as is similar to parasitism