Question

Describe each if the following concepts in ecology : b. niche c. K-selected species d. commensalism

Answer 1

b)

• Ecological niche

                              In ecology, a niche is the match of a species to a specific environmental condition. It describes how an organism or population responds to the distribution of resources and competitors ( example; by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (example; limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey. The type and number of variables comprising the the dimensions of an environmental niche vary from one species to another and the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts.

                     

                             The concept of ecological niche is central to ecological biogeography, which focuses on spatial patterns of ecological communities. Species distribution and thier dynamics over time result from properties of the species, environmental variation,etc. and interactions between the two-in particular the abilities of some species, especially our own, to modify their environments and alter the range dynamics of many other species. Alteration to an ecological niche by it's inhabitants is the topic of niche construction.

c)  

• K-selected species

                                               Also called K-strategist species whose populations fluctuate at or near the carrying capacity (K) of the environment in which they reside. Such species make up one of the two generalized life-history stratagies posited by American ecologist Robert MacArthur .

                     

                         K-selected species possess relatively stable populations and tend to produce relatively low numbers of offspring; however , indiviual offspring tend to be quite large in comparision with r-selected species. K-selected species are characterized by long gestation periods lasting several months, slow maturation with extended paternal care, and life long spans. In addition, they tend to inhabitat relatively stable biological communities,such as late-successional or climax forests. Examples of these species include birds,elephants,horses,primates and larger plants,

d)

• Commensalism

                       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. The commensal ( species that benefits from the association) may obtain nutrients,shelter,support or locomotionfrom the host species,which is substantially unaffected. The commensalism is often seen between larger host and a smaller commensal. The host organism is essentially unchanged by the interaction, whereas the commensal species may show great morphological adaptation.

                      One of the best examples of commensalism is the remora that rides attached to sharks and other fishes.