Effect * of species 1 on species 2

-

+

+

-Effect ofspecies 2

on species 1

COMPETITION

MUTUALISM

PREDATION

PREDATION

* On per capita growth rate

• Trophic Mutualisms• Protective Mutualisms• Dispersive Mutualisms

I. By Function:

Two ways to Classify Mutualisms

Obligate: species are so dependent on their mutualistic relationship that cannot live in its absence.

e.g., symbionts lichens leaf-cutter ants & fungustermites and gut fauna

Facultative: species can live without their mutualistic partner e.g., oxpeckers cleaner-wrasse many diffuse mutualists

Diffuse Mutualisms: Mutualistic interactions that where the“partner” can be one of any species, e.g., pollinators, seed dispersers.

Two ways to Classify Mutualisms

II. By relationship of mutualists for one another:

Trophic Mutualisms – involve a mutual exchange of energy/nutrients – specialized to the point of obligates

Lichens

Mycorrhizal fungi

Nitrification processes carried out only by specialized bacteria

NH3 NO2- NO2

- NO3-

Nitrosomonas (soil)Nitrosoccus (marine)

Nitrobacter (soil)Nitrococcus (marine)

Denitrification processes carried out only by specialized bacteria,such as Pseudomonas denitificans

NO3- NO2

- NO

Nitrogen fixation offsets Denitification and is accomplished by free-livingbacteria, such as Azotobacter, symbiotic bacteria, such as Rhizobium occurring in rootsof legumes, and cyanobacteria.

Nitrogen-fixing bacteria in root nodules of soybeans

Protective Mutualisms – involve an exchange of protection from predators/parasites often for an exchange of resources

Ant-leafhopper-goldenrod interactions

Alarm Calling• prey-2 predator

Tree hopper-ant mutualisms

#alarm signals before and after predatorcontact

Mechanically mimicking the tactile alarm call

Fewer LBremain

More antspatrolling

Dispersive Mutualisms – involve an exchange of a reproductive service often for an exchange of resources

Magnificent Hummingbird

BANFF NATIONAL PARK: Friendly Relations Between Clark’s Nutcracker and Whitebark Pine

Seed Dispersal

Seed dispersal

American robin and Viburnum

Experimental tests of mutualisms

Janzen’s study of Psuedomyrmexand the bullshorn acacia.

Beltian bodies

A comparison of acacia with ants and those with ants removed

Growth (cm) by

bullshorn acacia

Survival (%) by

bullshorn acacia

The benefit to the plant is fewerherbivorous insects

Mutualisms…..Really?

• 2000 interactions/day w/queue

• Eat parasites (coop) & mucosal tissue/scales (defect)

• The latter leads to client “jolt” so an observable cue

Jolts are predictors:

• 12-18/min among biting cleaners• 2-3/min among coop cleaners

Do clients image score?

• If previous client ends w/conflict (jolt/chasing): 100% bystanders (queue) depart• w/o conflict 100% approach

Audience effects?

• 17 vs. 6 cleaners spp showed (-) relationship between jolts and bystander presence

And also observed in Sergeant major

Mechanically mimicking the tactile alarm call

Fewer LBremain

More antspatrolling

Virola surinamensis 7Tetragastris panamensis 12Virola sebifera 6Caesearia corymbosa ** 22Gurarea glabra 19Didymopanax morototoni 37Miconia argentea 46

Plant species Avian frugivores

** Considered a Keystone species by Howe (1977) because it bears a fruit crop for 10 week period including December, the time of lowest fruit production in La Selva forest

Keystone Mutualists (Eco Eng, Foundation Spp)

Casearia corymbosa

Red-lored Amazon eats the arils and drops the fruit w/o dispersing

Chestnut-mandibled Toucan

Eats huge quantities of seeds, but a poor disperser. Toucans however depend on Casearia seeds in December when all their preferred foods are gone.

Disappearance of key fruit would push the tityra, the toucan, and other species to local extinction. Without its main disperser, Casearia, Virola (primarily dispersed by the Chestnut-mandibled toucan), and other treesdependent on these birds for dispersal would slowly lose their competitive position and diversity would slowly erode away in the tropical rain forest in La Selva.

The only known dependable disperser for Casearia seeds. Like the toucan, itappears to have no alternative food to eat in December.

Alternative *forms* of mutualisms

(1) Physical Ecosystem Engineers (after Jones et al. 1997)

What does a tree do in the forest?

- living and dead tissues are eaten by animals (+,-) - competes with other plants for water and nutrients (-,-)

- branches, bark, roots, and leaf surfaces make shelter, resting locations, and living space- small pools for organisms are created where water gets channeled into crotches- soil cavities that from when roots grow provide places to live and cache food- leaves and branches cast shade, reduce the impact of rain and wind, moderate temperature extremes, and increase humidity in the under story and soil - root growth aerates the soil, alters its texture, and affects the infiltration of water

And more…..

Jones et al. called these modifications ecosystem engineering

And there are many, many, many examples.

Some almost trivial, such as plants creating shade??

Others are very obvious….

Sometimes it’s the non-living structure left behind that providesthe benefit, other times it may benew structures created as a resultof an animal’s activity.

And EE have bothpositive and negativeeffects on individualSpecies or the

Sometimes Eco. Engineers are called Foundation species when they form the base from which a whole community of species is built

Coral reefs Kelp forest