Plant Ecology Notes

ECOLOGICAL NICHE Habitat and Ecological niche Habitat - (Where as Species live) It is a environment where Organism live and it indude all parameter like bionic and abionic factors so, it is a area where living things can grow and survive. Example - Forest, Desert, Aquatic and terrestrial habitat etc. Ecological niche:- (How Species live) A set of f. environmental Condition and resources under which a species can survive, grow, reproduce and function define the ecological niche. The term 'niche' was used for the first time Joseph Grinnell (1917). It is the functional area of organisms or Species It is part of habitat and is constricted as Compare to habitat. TYPES OF NICHE Spatial/Habitat niche Given by Joseph Grintiell. furictional status of Organism in its community. Tropic niche Given by charles Elton. Trophic position of organisms in its community. Multidimensional/n-dimensional hyper volume Niche descrite by Hutchinson (1957) It is defined n-dimensional hypervolume, where. in is the number of dimensions that make up the niche within an grow and reproduce Organism can survive, MAJOR NICHES:- 1. FUNDAMENTAL NICHE * fundamental niche ore pre-competitive niche is the range of environmental conditions in which a particular species can live. * This means it defines a collection of conditions and Sources in which the species reproduce. can survive, grow and ForExample ple:- The male red-winged blackbird. hold the prime real estate in the marshes in the early spring. However, with Seasonal progress, ir tricoloured tricoloured blackbird which are more aggressive and take over the move into the marshes. best territory. 2. Realized niche: Realized niche or post competitive niche is the range of environmental condition in which the Species actually live. It is always is always smaller than the coresponding fundamental niche of the specier and is Considered as a subset of a fundamental niche. when the species in the fundamental niche has to face various interactions and pressure from the environment, it is forced to move into small REALIZED NICHE FUNDAMENTAL NICHE Aniche of an Organism quen that there are tentang factors on the environment or resources the organism can use Also called pre-competitive niche A type of theoretical niche Large in Size Elaborates on various roles of a particular Species. There is no competition either for resources or peredators REALIZED NICHE A niche that i occupied by a viable population of a species in the presence of Competitor species. Called post-competitur niche where the species actually Lives Small in Size Elaborates on what the species actually do. A competition occurs for both risererces and Predattis DIFFERENCE BETWEEN HABITAT && NICHE HABITAT NICHE A specific physical space occupied by organism (spe an A functional space occupied by in an erganism same ecosysten e Same habitat may be shared by many organium (species) A single niche is occupied by a single species. habitat specificity is exhibited by organism. Organism may change their reason niche with time and FUNDAMENTAL AND REALIZED NICHE Asymmetric competition, incomplete o niche overlap. Speues 1 (Strong Competitior) Species 2 (weak competitor) fundamental niche -Realizedniche Number of individuals wing resources Niche Crange of resources used) NICHE OVERLAP AND NICHE WIDTH NICHE overlap:- The sharing of niche space by two or more species & called niche overlap. It is an index of similarity utilisation of two species between the resource NICHE WIDTH :- describes the extent of the realized niche occupied by an organism. condition and avilable resource Species as well as Suitable conviromental appropriate to that interspecific interactions. - Resource use leg. Seld size eaten) COMPETITIVE EXCLUSION PRINCIPLE It is also known as Gause's principle. Two species competing for the same resource cannot Coexist indefinately. If two organism is living in the Same habitat but differunt niche results stably coexist together without any Competition. If two organism lwing in same niche results can't Coexist together and competition will results in one species elimination. "Complete competitors cannol Coexist" Garret Haldir. Resource partitioning: Resource partitioning occurs when two species coevist - spite of appa apparent competition for the same in resoluces. But they actually occupy slightly different niches. By pursuing slightly different resource OR obtaining resources resources in slightly different ways, Endividuals minimize competition and maximise Success. 4 Dividing tip resources in this manner is partitioning. called resource D five Species of warblers coexist in spruce trees by feeding on insects in different regions of the tree and by using different feeding behaviours to obtain CHARACTER DISPLACEMENT As a result of resource partioning, certain characteristics may enables individuals to obtain resources in their partitions more successfully. Selection of of these characteristics reduces Competition with individuals in other sartitions and leads to divergence of feature This is called character displacement of Niche Shift According to them the ecologual characters. displacement driven by competition. As the term character displacement is commonly used, it generally refers to morphological differences due to competitions. which, character displacement is the situation in when two species that live together en same environment tends to diverse in those characteristic that cuerlap. Initially 2 species encounter each other in overlap of phenotype associated with resource use and reproduction. Before character displacement Frequency 1 2 Resource utilization * character displacement arises avoiding the competition. After character displacement frequency 2 Resource Utilization Result of character displacement * Minimize niche Overlap * Avoid competitive exclusion"