Mutualism

Symbiosis

-2 organisms live together in close association (physical contact) -May involve parasatism, mutualism, or commensalism

Dispersive Mutualism

-Animals transport pollen or seeds

Example of Dispersive mutualism (Seed dispersal)

-Blue jays eat acorns in the fall (disperse seeds over long distances and bury them in open areas. Some are left to germinate) -Monkeys eat fruit and defecate seeds. Dung beetles roll up dung and bury eat protecting seeds from seed eaters

Commensalism examples

-Elephants kill trees opening up habitat for grassland species -Cattle egrets eat insects stirred up by cattle -Arctic foxes eat food scraps left behind by polar bears

Trophic Mutualism (Grazing associations)

-Grazing by bison and pronghorns lower grass height providing better habitat for prairie dogs -bison forage on prairie dog town edges where young grasses have high nutrition value -Pronghorn forage in prairie dog town centers where forbs dominate over grasses

Example of Dispersive mutualism (hummingbirds)

-Hummingbirds are attracted to red and bright colors -Bill shapes of hummingbirds mimic flower shapes

Defensive Mutualism

-1 partner protects the other from predation, herbivory, or parasitism

Trophic Mutualsim

-1 partner obtains energy and nutrients from the other

Example of Trophic Mutualism

-Microbial fermentation -Rumenants (mammals with 4 stomachs) have bacteria in rumen which breaks down cellulose and synthesizes proteins and vitamins -Allows them to survive on low nutrition diet

Example of Dispersive mutualism (Bat pollinators)

-Nectivorous bats have long grooved tongues and broad wings for hovering -Bat pollinating flowers are drab and strongly scented (bats have strong sense of smell)

Obligate Mutualism

-Partners are fully dependent on each other for survival

Facultative mutualism

-Partners could survive without each other, but still benefit from association

Evolution of mutualistic relationships

-Probably started out as a predator prey relationship, parasitic host relationship -Both species exploit eachother in way that benefits both

Mutualism

-Relationship between 2 species in which both benefit -Can be either symbiotic or nonsymbiotic

Example of Defensive Mutualism

-Soay sheep on Scottish islands -As grazing pressures increase on red fescue grasses, rate of infection of fungi increases -Sheep crash every 3-5 years due to the poisioning of endophytic fungi