LEPTOSPIROSIS

DEFINITION OF NICHES

A niche refers to the way in which an organism fits into an ecological community or ecosystem. Through the process of natural selection, a niche is the evolutionary result of a species morphological (morphology refers to an organisms physical structure), physiological, and behavioral adaptations to its surroundings.

EXAMPLE OF NICHES

The male red-winged blackbird's mating call can be heard in the marshes in early spring. At that time, they hold the prime real estate in the marsh. However, as the season progresses, the more aggressive tri-colors blackbirds move in. The tri-colors take over the best territory and force the red-wings to choose the leftovers. The entire marsh represents the red-winged blackbirds' fundamental niche.

Spartina alterniflora is a grass species that is very tolerant of salt. It lives in salt marshes along the eastern North American coast. These marshes go underwater at high tide. While it is found all along the coast, it does not live in nearby freshwater environments.

Coyotes (Canis latrans) are successful niche generalists. Originally native to deserts, these omnivorous opportunists are able to adapt to almost all habitats at many different successional stages, and altitudes up to around 9800 ft.

Their diets are highly varied, primarily consisting of rats, mice, ground squirrels and carrion, they also feed on snakes, birds, tortoises, fruit, nuts and grass; they eat almost anything they can find and they cause big problems to farmers by hunting sheep and domestic fowl. They can hunt by digging out prey, or ambushing and stalking, and can reach speeds of up to 40mph. They are also able to hunt solitarily, in pairs or in small packs. They are very tolerant of human activities and so have managed to integrate within urban areas, feeding from human waste.

Because coyotes are able to adapt their niche quickly to changes in their environment, their populations are ever increasing, often to the detriment of other species, whose niche they exploit, causing competition. However, the removal of coyotes entirely from an ecosystem can be equally damaging; coyotes’ natural niche includes the predation of mesocarnivores such as foxes and raccoons, which eat songbirds and duck eggs. In the absence of coyotes, numbers of these birds decline rapidly

COMMENSALISM

Commensalism is a type of relationship between two living organisms in which one organism benefits from the other without harming it. A commensal species benefits from another species by obtaining locomotion, shelter, food, or support from the host species, which (for the most part) neither benefits nor is harmed. Commensalism ranges from brief interactions between species to life-long symbiosis.

Bromeliads

While bromeliads themselves can be commensal or parasitic, the pools of water they collect are a vital environment for dozens of commensal species, from insects to crabs to salamanders. Most of these species do the bromeliad no harm, but benefit from the shelter and water provided by the plant.

MUTUALISM

Mutulaism describes a type of mutually beneficial relationship between organisms of different species. It is a symbiotic relationship in which two different species interact with and in some cases, totally rely on one another for survival. . An example of mutualism involves  nitrogen-fixing  bacteria   and  legumes (see Figure below).

Nitrogen-fixing Bacteria and Legumes

 Symbiotic root nodules on alfalfa containing nitrogen-fixing Rhizobium bacteria. Inga Spence/ Photolibrary/Getty Images

Mutualism in Nitrogen-fixing Bacteria and Legumes: Nitrogen-fixing bacteria live in the root hairs of legume plants where they convert nitrogen to ammonia. The plant uses the ammonia for growth and development, while the bacteria receive nutrients and a suitable place to grow.

Some mutualistic symbiotic relationships involve one species living within another. This is the case with legumes (beans, lentils, peas, etc.) and some types of nitrogen-fixing bacteria. Atmospheric nitrogen is an important gas that must be changed into a usable form in order to be utilized by plants and animals. This process of converting nitrogen to ammonia is called nitrogen fixation and is vital to the cycle of nitrogen in the environment. Rhizobia bacteria are capable of nitrogen fixation and live within the root nodules (small growths) of legumes. The bacteria produce ammonia, which is absorbed by the plant and used to produce amino acids, nucleic acids, proteins, and other biological molecules necessary for growth and survival. The plant provides a safe environment and adequate nutrients for the bacteria to grow.