Examination of the Ecological Niche of Gilt Darter ( Percina evides) Using Morphological Data

An organism's niche is the ecological space that it occupies (Hutchinson 1957). Inthe absence of other species, a species may utilize the full range of biotic and abioticresources that it needs to survive and reproduce (Hutchinson 1957). However,competition for limited resources between ecologically identical entities will lead to theextinction of one or more species (Gause 1934, Hardin 1960, Levin 1970). Stable co-existence of different species may occur if, over time, competition and natural selectionresult in niche differentiation and, therefore, different resource and habitat use(MacArthur and Levins 1964, Schluter 1994). The partitioning of resources results innarrower ecological niches for competing species. The narrowed niche that a speciesoccupies as a result of competitive interactions is its "realized" niche (Hutchinson 1957,Schoener 1974, Morin 1999)