Biological interactions result from the fact that
organisms in an
ecosystem interact with each other. In the natural world, no organism is an autonomous entity isolated from its surroundings. It is part of its
environment, rich in living and non-living elements, all of which interact with each other in some fashion. An organism's interactions with its environment are fundamental to the survival of that organism and the functioning of the ecosystem as a whole. Sign-mediated interactions in which molecules serve as signs are the characteristic feature of communicative interactions.
[1]In ecology, biological interactions are the relationships between two species in an ecosystem. These relationships can be categorized into many different classes of interactions based either on the effects or on the mechanism of the interaction. The interactions between two species vary greatly in these aspects as well as in duration and strength. Species may meet once in a generation (e.g. pollination) or live completely within another (e.g. endosymbiosis). Effects may range from one species eating the other (predation), to mutual benefit (mutualism). The interactions between two species need not be through direct contact. Due to the connected nature of ecosystems, species may affect each other through intermediaries such as shared resources or common enemies.
Terms which explicitly indicate the quality of benefit or harm in terms of fitness experienced by participants in an interaction are listed below. There are six possible combinations, ranging from mutually beneficial through neutral to mutually harmful interactions. The level of benefit or harm is continuous and not discrete, such that an interaction may be trivially harmful through to deadly, for example. It is important to note that these interactions are not always static. In many cases, two species will interact differently under different conditions. This is particularly true in, but not limited to, cases where species have multiple, drastically different life stages.
Amensalism between two species involves one impeding or restricting the success of the other its being affected positively by the presence of the other.[2] It is a type of symbiosis. Usually this occurs when one organism exudes a chemical compound as part of its normal metabolism that is detrimental to another organism.
