Definitions of the niche date back to 1917,[28] but G. Evelyn Hutchinson made conceptual advances in 1957[29][30] by introducing a widely adopted definition: "the set of biotic and abiotic conditions in which a species is able to persist and maintain stable population sizes."[28]:519 The ecological niche is a central concept in the ecology of organisms and is sub-divided into the fundamental and the realized niche. The fundamental niche is the set of environmental conditions under which a species is able to persist. The realized niche is the set of environmental plus ecological conditions under which a species persists.[28][30][31] The Hutchinsonian niche is defined more technically as a "Euclidean hyperspace whose dimensions are defined as environmental variables and whose size is a function of the number of values that the environmental values may assume for which an organism has positive fitness."[32]:71 Biogeographical patterns and range distributions are explained or predicted through knowledge of a species' traits and niche requirements.[33] Species have functional traits that are uniquely adapted to the ecological niche. A trait is a measurable property, phenotype, or characteristic of an organism that may influence its survival. Genes play an important role in the interplay of development and environmental expression of traits.[34] Resident species evolve traits that are fitted to the selection pressures of their local environment. This ten

s to afford them a competitive advantage and discourages similarly adapted species from having an overlapping geographic range. The competitive exclusion principle states that two species cannot coexist indefinitely by living off the same limiting resource; one will always outcompete the other. When similarly adapted species overlap geographically, closer inspection reveals subtle ecological differences in their habitat or dietary requirements.[35] Some models and empirical studies, however, suggest that disturbances can stabilize the coevolution and shared niche occupancy of similar species inhabiting species-rich communities.[36] The habitat plus the niche is called the ecotope, which is defined as the full range of environmental and biological variables affecting an entire species. Organisms are subject to environmental pressures, but they also modify their habitats. The regulatory feedback between organisms and their environment can affect conditions from local (e.g., a beaver pond) to global scales, over time and even after death, such as decaying logs or silica skeleton deposits from marine organisms.[37] The process and concept of ecosystem engineering has also been called niche construction. Ecosystem engineers are defined as: "organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. In so doing they modify, maintain and create habitats.