Ecological interactions (article) | Ecology | Khan Academy
Symbiotic relationships are a special type of interaction between species. transport symbiosis, since the first organism provides not only food. Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit from each The commensal relation is often between a larger host and a smaller. Fleas get a free ride - and there's not much in it for the dog. ecologists use “ symbiosis” to refer to any relationship between two organisms.
Arguments[ edit ] Whether the relationship between humans and some types of gut flora is commensal or mutualistic is still unanswered. Some biologists argue that any close interaction between two organisms is unlikely to be completely neutral for either party, and that relationships identified as commensal are likely mutualistic or parasitic in a subtle way that has not been detected.
For example, epiphytes are "nutritional pirates" that may intercept substantial amounts of nutrients that would otherwise go to the host plant. Similarly, phoretic mites may hinder their host by making flight more difficult, which may affect its aerial hunting ability or cause it to expend extra energy while carrying these passengers.
Types[ edit ] Phoretic mites on a fly Pseudolynchia canariensis Like all ecological interactions, commensalisms vary in strength and duration from intimate, long-lived symbioses to brief, weak interactions through intermediaries.
Phoresy[ edit ] Phoresy is one animal attached to another exclusively for transport, mainly arthropodsexamples of which are mites on insects such as beetlesflies or beespseudoscorpions on mammals  or beetles, and millipedes on birds.
Inquilinism[ edit ] Inquilinism: Tillandsia bourgaei growing on an oak tree in Mexico Inquilinism is the use of a second organism for permanent housing. Examples are epiphytic plants such as many orchids that grow on trees,  or birds that live in holes in trees. This is to the advantage of the mimic but to the detriment of both the model, whose protective signals are effectively weakened, and of the dupe, which is deprived of an edible prey.
For example, a wasp is a strongly-defended model, which signals with its conspicuous black and yellow coloration that it is an unprofitable prey to predators such as birds which hunt by sight; many hoverflies are Batesian mimics of wasps, and any bird that avoids these hoverflies is a dupe.
Amensalism is an asymmetric interaction where one species is harmed or killed by the other, and one is unaffected by the other. Competition is where a larger or stronger organism deprives a smaller or weaker one from a resource. Antagonism occurs when one organism is damaged or killed by another through a chemical secretion. An example of competition is a sapling growing under the shadow of a mature tree.
The mature tree can rob the sapling of necessary sunlight and, if the mature tree is very large, it can take up rainwater and deplete soil nutrients.
Throughout the process, the mature tree is unaffected by the sapling. The Human Microbiome The human microbiome describes the genes associated with all the microbes that live in and on a human.
The microbes are mostly bacteria but can include archaea, fungi, and eukartyotic microbes The locations include skin, upper respiratory tract, stomach, intestines, and urogenital tracts.
Colonization occurs soon after birth, as infants acquire microbes from people, surfaces and objects that they come in contact with.
Five Types of Ecological Relationships | Education - Seattle PI
Gut microbes and human metabolism Most of the microbes associated with the human body are found in the gut, particularly about hours after eating a meal when the microbial population dramatically increases. The gut microbiota is extremely diverse and it has been estimated that from species of bacteria live in the human gastrointestinal tract typically described as from pounds of bacteria! The gut microbes are essential for host digestion and nutrition, aiding in digestion by breaking down carbohydrates that humans could not break down on their own, by liberating short chain fatty acids from indigestible dietary fibers.
In addition, they produce vitamins such as biotin and vitamin K.
Commensalism - Wikipedia
Gut microbes and obesity There has been increased interest in the microbial gut population, due to the possibility that it might play a role in obesity. Although currently hypothetical, research has shown that obese mice have a microbial gut community that differs from the microbes found in the gut of non-obese mice, with more Firmicutes bacteria and methanogenic Archaea.
It has been suggested that these microbes are more efficient at absorbing nutrients. Human microbiome and disease It has been shown that microbiota changes are associated with diseased states or dysbiosis. Preliminary research has shown that the microbiota might be associated rheumatoid arthritis, colorectal cancer, diabetes, in addition to obesity.
Some researchers used advanced DNA-sequencing techniques to determine what microbes are present and in what populations. Many current research projects are focused on determining the role of the human microbiome in both health and the diseased state.
There is no doubt that our knowledge will continue to grow as we find out more about the vast populations of microbes that live in and on us. Biofilms Biofilms are a complex aggregation of cells that are encased within an excellular matrix and attached to a surface. Bioforms can form on just about any surface and are common in nature and industry, being found on the surfaces of rocks, caves, pipes, boat hulls, cooking vessels, and medical implants, just to name a few.
They have also been around a long time, since the fossil record shows evidence for biofilms going back 3.
The microbial community of a biofilm can be composed of one or two species but more commonly contains many different species of bacteria, each influencing the others gene expression and growth. Biofilm development The basic steps for biofilm formation can be broken down into four steps: Cell disposition and attachment — in order for biofilm development to occur, free-floating or planktonic cells must collide with a suitable surface.
Typically the surface has been preconditioned with the deposits of environmental proteins and other molecules. Colonization — cell-to-cell signaling occurs, leading to the expression of biofilm specific genes.