Question

What is a niche, and is this a property of a particular species or of the environment?

What is the difference between an r-selected and a K-selected species? Where do the letters r and K come from?

Answer 1

Ecological niche is a term for the position of a species within an ecosystem, describing both the range of conditions necessary for persistence of the species, and its ecological role in the ecosystem. Ecological niche subsumes all of the interactions between a species and the biotic and abiotic environment, and thus represents a very basic and fundamental ecological concept. The tentative definition presented above indicates that the concept of niche has two sides which are not so tightly related: one concerns the effects environment has on a species, the other the effects a species has on the environment.

the ecological niche was defined by a place a species can take in nature, determined by its abiotic requirements, food preferences, microhabitat characteristics (for example a foliage layer), diurnal and seasonal specialization, or predation avoidance. This concept is associated mostly with Joseph Grinnell, who first introduced the term. He was especially interested in factors determining where we can find a given species and how niches, generated by the environment, are filled.

the niche is the property of the environment.

Niche as a species position in a community – formalization of ecological niche concept The emphasis on the diversity of ecological communities and interspecific competition within them in the second half of 20 th century has lead to the formalization of niche concept, and an emphasis on the properties of the niches which enable species coexistence within a habitat.

2. The difference between an R-selected species and a K-selected species is that the R-selected species live in variable, unstable habitats, while K-selected species reside in stable environments. R-selected species produce many offspring, but only a few live out their lifespan. K-selected species have a few offspring that have a long life expectancy

Organisms considered R-selected species tend to be small, reach sexual maturity early in life and reproduce a single time. Mosquitoes are an example of an R-selected species.

The K-selected species are larger in size, reach sexual maturity later in life, reproduce many times during their life span and require more energy to procreate. Whales, giraffes and elephants are examples of K-selected species.

The terms "r-selected" and "K-selected" come from a description of the population growth regimes of the two types of organisms.