Mutualism, Commensalism, and Amenalism

mutualism (+,+)

Both species benefit

Two types:

• Obligate: partners need each other

  • pollinators/plants pairings: they need each other and won’t survive in the absence of the other.

• facultative: partners could exist independent of each other, but they perform better together

obligate mutualism

Two species depend on each other for survival and cannot survive without each other.

pollinator and plant pairings

facultative mutualism

Two species can exist independent of each other, but they perform much better together.

Mutualism equation

dN1/dt = r1N1 [(K1 - N1 + aN2)/ K1]

dN2/dt = r2N2 [(K2 - N2 + BN1)/ K2]

what benefits do organisms get from mutualism

• nutritional

• supply of energy

• protection

• transportation

nutritional benefit

either the breakdown of compounds by digestion for a partner, or supply of growth factors or nutrients by synthesis or concentration

supply of energy

generally from photosynthesis

protection

from environmental variations or enemies

transportation

either from a suitable/unsuitable environment or by dispersal of gametes or propagules.

symbiosis

when 2 organisms are living together, but it doesn’t specify their relationship.

symbiosis and mutualism are

not the same thing. But could also be symbiotic mutualism.

In mutualism…

both species exploit each other, but they both benefit. This can lead to cheating (can lead to parasitism) if not for the presence of sanctions.

sanctions

Sanctions prevents one species from taking over or cheating. The stricter the sanction, the less likely the organisms is to deviate from mutualism.

Sanctions in ecology refer to the mechanisms or behaviors that individuals or species employ to enforce cooperation or punish non-cooperative behavior within a social group. These sanctions can include various forms of punishment or exclusion, such as aggression, withholding resources, or social ostracism. The purpose of sanctions is to maintain social order, promote cooperation, and deter individuals from engaging in behaviors that are detrimental to the group or ecosystem.

Commensalism (+,o)

One species benefits from the interaction, while the other is neutral and receives no benefit or incurs a cost.

processing chain commensalism

One organism is the upstream consumer of a resource. The upstream consumer modifies the resource that then benefits the downstream consumer.

Amensalism (o,-)

One organism incurs a cost, while the other is neutral. An organisms hurts another without benefitting from it.

context dependence

The interactions between 2 organisms exist on a spectrum and certain variables can influence the relation exhibited.

context dictates the type of relationship organisms will have (resources available, climate, etc).