Transcript niches ppt
What is an ecological niche and how outcomes can occur if two similar species live too close to one another? An ecological niche is the location of a species or population in relation to others within its ecosystem Trespassers will be prosecuted - termed by G.E. Hutchinson a "hypervolume." Example: dolphins can be part of different niches if they belong to different pods (groups) and use different resources and foraging methods. ROOTS OF THE TERM: Word derived from French nicher (to nest) - The ecological term was coined by the naturalist Joseph Grinnel in 1917, in his paper "The niche relationships of the California Thrasher." - In 1927 Charles Sutherland Eton, a British ecologist, gave the first working definition of the niche concept. -The niche concept was popularized by the zoologist G. Evelyn Hutchinson in 1957 Dimensions of a niche: biotic and abiotic factors affecting presence of a species/organism. Factors include life history, habitat, trophic position ( place in food chain), geographic range. THE FUNDAMENTAL NICHE The full range of environmental conditions (biological and physical - light, nutrients, structure, etc. ) under which an organism can exist. THE REALIZED NICHE Because of pressure from, and interactions with other organisms (e.g. superior competitors), species are usually forced to occupy a niche that is narrower than their fundamental niche, and to which they are highly adapted. ADAPTIVE ZONE Coined by the paleontologist, George Gaylord Simpson, and refers to a set of ecological niches that may be occupied by a group of species that exploit the same resources in a similar manner. VACANT NICHES An ecological location not inhabited by any species. Two similar species cannot live too close to each other/ in the same niche because they cannot depend on the same resources. If they do, there will be competition for survival that will result in one species dominating and the other going extinct or through behavioral/ evolutionary change adapt to a new niche. Competitive Exclusion Principle/Gause's Law of competitive exclusion: two species competing for the same resources cannot stably coexist if other ecological factors are constant. Outcomes of two species with same niche/resources: One species dominates, the other goes extinct One species dominates, the other finds new niche Introduced species may occupy or invade niches of native organisms biological pollution by the exotic or ivasive species. sometimes outcompete the indigenous species. Different species can hold similar niches and the same species may occupy different niches. The Australian grasslands species, though different from those of the Great Plains grasslands, occupy the same niche. Once a niche is left vacant, other organisms can fill that position. For example, the niche that was left vacant by the extinction of the tarpan has been filled by other animals (in particular a small horse breed, the konik- below). Niche modeling: The mathematical representation of a species' fundamental niche in ecological space, and its subsequent projection back into geographic space.