11 Mutualism Chapter 15

22 Introduction _______________: Interactions between individuals of different species that benefit both partners. – ___________________ occurs when a species can live without its mutualistic partner. – ___________________ occurs when a species is dependent on a mutualistic relationship. Margulis and Fester amassed evidence …

33 Plant Performance and Mycorrhizal Fungi Two most common types of mycorrhizae: 1) (AMF) Produces arbuscules -

44 Plant Performance and Mycorrhizal Fungi Two most common types of mycorrhizae: 2) Ectomycorrhizae (ECM)

55 Mycorrhizae and Plant Water Balance Allen and Allen studied water relations of grass Agropyron smithii. – Plants with mycorrhizae maintained …

66 Mycorrhizae and Plant Water Balance Hardie suggested mycorrhizal fungi improve water relations by providing more extensive contact with ____________ in rooting zone and providing extra area for ______________.

77 Nutrient Availability and Mutualistic Balance Sheet Johnson investigated whether fertilization can select for less mutualistic mycorrhizal fungi. – Fungal partner received an equal or greater quantity of photosynthetic product in trade for … In nutrient poor environments, many plants invest …

88 Nutrient Availability Results suggested mycorrhizal fungi from unfertilized soils supplied plants with … – Plants able to invest more energy in above-ground photosynthetic material… principle of ?

99 Ants and Bull’s horn Acacia Herbivores attempting to forage on accacia plants occupied by accacia ants are met by a large number of fast, agile, highly-aggressive defenders. Ant Benefits: – – –

10 Ants and Bull’s horn Acacia

11 Experimental Evidence For Mutualism Janzen demonstrated ants significantly improve plant performance. – Acacias without ants had … – Suckers growing from accacia stumps occupied by ants lengthened at _______________rate of suckers without ants. Suckers with ants ______________________the rate of suckers without ants.

12 Coral Mutualisms Zooxanthallae and Corals – Zooxanthallae live within coral tissues. – Corals induce release of organic compounds with “signal compounds” that …

13 Coral Mutualisms Corals also control rate of zooxanthallae population growth and density by influencing ____________________________. Main zooxanthallae benefit appears to be access to … – Uptakes ___________________ excreted by coral.

14 Coral Protection Mutualism Glynn found 13 coral species protected by … – Crustacean mutualists substantially improved chances coral will avoid attack by sea stars.

15 Coral Protection Mutualism Also found crab activity promotes coral health and integrity. – Pocillopora coral increases production of _____ _________ in the presence of crabs. Digestive tract of crabs inhabiting corals contained …

16 Evolution of Mutualism Theory predicts mutualism will evolve where the benefits of mutualism exceed the costs. – Keeler developed models to represent relative costs and benefits of several types of mutualistic interactions. _________________ – Give and receive benefits. ______________________ – Give, but do not receive benefit.

17 Evolution of Mutualism _____________________ – Neither give nor receive benefit. For a population to be mutualistic, fitness of successful mutualists must be ____________ than unsuccessful or non-mutualists. – If not, natural selection will eventually …

18 Facultative Ant-Plant Mutualisms Keeler proposed for a facultative ant-plant mutualism to evolve and persist… proportion of plant’s energy budget ants _____ from destruction by herbivores… must exceed proportion of the plant’s energy budget ______ in _____________ and ______.

19 Facultative Ant-Plant Mutualisms So what conditions might produce higher benefits than costs?

20 Facultative Ant-Plant Mutualisms p [H ( 1 – D ) A ] > I A

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