animal associations - categories
HOMOSPECIFIC
- same species [1]
- associations which form the basis of social behaviour
HETEROSPECIFIC
- 1 + x species
commensalism
- regular, close association
- one species benefits, other does not
inquillism
- lives in host
- Tenquilus = tenant
mutualism
- mutus = exchange
- parasymbiosis
- nobody benefits
- e.g. different species of bird living in same tree except mabye tearning each other
- animals feeding within sight of each other
- do not compete with each other ecologically
alarm calls
parabiosis
- bilateral association with entire species
parasitism
- lives inside or attached to another organism, the host, obtaining nourishment from its tissues or fluids
- Implies intimate, macromolecular contact, where excretions and secretions of one organism may interact with the cells and fluids of the other in such a way that the parasite may be recognised by the host as being foreign, non-se;lf, or antigenic
- If an animal or plant is recognised as antigenic, it is a parasite
e.g.
parasitism of tapeworm in hind part of gut:
- worm uses the wall of the gut for attachment only minimally
- absorption of nuitients takes place in the region of excretion and tapeworms excretory products do not affect the host
Commensalism examined
- Commensalism originally meant "eating at the same table". But this suggests that there are only nutritional linkages.
- It is now termed a oone sided heterospecific association
- commensalism can range from an association where nutrition forms some part of the relationship to where it is completely excluded
- there have been some ecological definitions
- Any definition needs to carefuly qualified
Ecological definition of commensalism
In commensalism animals receive unilateral benefit but this not the same as parasitism
- Animals living in the same locality where the "host" is part of the environment
- The relationship consists of a whole range of associations where animals or animals and plants gain advantage through living togetherthe relationship stops just short of predation
- There can be subdivisions of the umbrella term commensalism based on nutritional themes