Biological Symbiosis

Symbiosis, first defined by botanist Anton de Bary in 1878, typically refers
     to a long-term association between two or more species.
And the intimacy between the organisms varies depending on the association.

Symbiotic associations are varied, and may include, but are not limited to,
     interactions where one organism benefits but not the other, where
     neither organism benefits, where both organisms benefit.

Intimate partnerships involve a physical fusing together of two or more
     different organisms, with each providing a survival benefit to the other.
This may or may not involve the merging of their genomes, known as

The first organisms were simple systems: bacteria and viruses.
Biologist Lynn Margulis has demonstrated that under extreme environmental
     stress, one type of bacteria would invade another.
Sometimes the invader would fail to kill the host.
Likewise the host would be unable to repel the invader.
Overnight, rather than gradually, a new kind of relationship was formed;
     an organism would emerge more complex than either of the two alone,
     better able to compete, survive, and reproduce.

In addition, external relationships have evolved between species,
     such as flowering plants and insects, or trees and fungi.
Flowering plants, which are immobile, and free-flying insects
     are less intimate partners.
They share a deep behavioral connection.
For example, flowers attract bees and supply them with nectar.
The bees, in turn, brush up against the plant’s sticky pollen
     spreading it from flower to flower,
     which insures the reproduction of more plants.

Symbiosis is a continually evolving biological process
     that is responsible for increasingly complex morphology
     throughout nature.