Commensalism

The term commensalism (Latin comme salis, table companion ') is used for a form of interaction between individuals of different species, for that of the other type is positive for members of one type neutral. The term is used in different areas with slightly different definition.

• In the original definition, which goes back to the works of the Belgian parasitologist and paleontologist Pierre- Joseph van Beneden, a commensal is a " blackhead ", which is dependent for its food on an organism of a different kind, by partaking of the food, these but (as opposed to a parasite ) is not damaged. In close spatial coexistence of the host organism imaging and which miternährende commensal is called. The host arise while no major upstream or adverse effects. Only the commensal is the beneficiary of living together and is mostly dependent on the host. The commensal mostly feed on waste or surplus food of the host, but this does not draw vital substances.

• Derived from this meaning, the term applied to any type of interaction between the two species, which is positive for a partner neutral for the other. In this case, it may also be an interaction irrespective of feeding relations ( technical term: " trophic " relationships ) act. The following positive ( ), negative (-) and neutral ( 0) Effect of assorted kinds of relationships are being sorted in the form of an interaction matrix. This results in five possible relationship couples - or six, if you will consider the trivial case that the species did not interact (pairing 0/0). Commensalism is the definition according to the pairing ( / 0), ie positive / neutral. Since at least one partner benefits, provides this interspecific interaction is a form of Probiose represents the relationship will not be here for the mechanisms (eg, food relations ), but only after the effects defined. This use of the term goes back to the influential American ecologist Warder Clyde Allee.

• When considering mammals, it has become common to refer to as commensals such species that depend for their food directly to people and their inventories.

Man

In humans include those microorganisms to the species, which colonize different micro habitats as ecto- or Endokommensalen and are collectively referred to there as the respective normal flora. This is, however, partly also to mutualism, since many of the microorganisms provide a protective environment and the people is an imbalance of flora brings health problems, and therefore, strictly speaking, this can not be counted among the commensals. These are

• On the skin, the different ( according to area of ​​skin ) skin flora
• In the oral cavity, the oral flora, not protect the area of ​​the teeth, however, before the acid-forming and decay-causing microorganisms
• In the upper respiratory tract the local physiological colonization with microorganisms
• In the intestine after intestinal section differ distributed intestinal flora
• In the female ( in the vagina ), the age- dependent different compositions vaginal flora

Animals

A typical example of commensalism are, for example, the scavengers of the steppes and deserts, follow the larger hunters. Occasionally commensals can become indirect competitors by mass occurrence or food shortages.