scholarly journals How the competitive exclusion principle can be validated using optical density measurements collected on artificially reconstituted soil ecosystems

2019 ◽  
pp. 001-006
Author(s):  
Hajji ME
Keyword(s):  
Optical Density ◽  
Competitive Exclusion ◽  
Exclusion Principle ◽  
Competitive Exclusion Principle ◽  
Density Measurements ◽  
Soil Ecosystems ◽  
Reconstituted Soil

Ecological Theory and the Superfluous Niche

2019 ◽  
Vol 47 (1) ◽  
pp. 105-123
Author(s):  
James Justus ◽  
Keyword(s):  
Competitive Exclusion ◽  
Ecological Theory ◽  
Character Displacement ◽  
Exclusion Principle ◽  
Limiting Similarity ◽  
Competitive Exclusion Principle ◽  
Ecological Equivalence

Perhaps no concept has been thought more important to ecological theorizing than the niche. Without it, technically sophisticated and well-regarded accounts of character displacement, ecological equivalence, limiting similarity, and others would seemingly never have been developed. The niche is also widely considered the centerpiece of the best candidate for a distinctively ecological law, the competitive exclusion principle. But the incongruous array and imprecise character of proposed definitions of the concept square poorly with its apparent scientific centrality. I argue this definitional diversity and imprecision reflects a problematic conceptual indeterminacy that challenges its putative indispensability in ecology.

The distribution and behavior of Peromyscus maniculatus gracilis and Peromyscus leucopus noveboracensis (Rodentia: Cricetidae) in a southeastern Ontario woodlot

1970 ◽  
Vol 48 (6) ◽  
pp. 1187-1199 ◽  
Author(s):  
Donald A. Smith ◽  
S. Wayne Speller
Keyword(s):  
Competitive Exclusion ◽  
Peromyscus Leucopus ◽  
Population Characteristics ◽  
Exclusion Principle ◽  
Dense Population ◽  
Competitive Exclusion Principle ◽  
Upland Forest ◽  
Live Trapping ◽  
Tree Holes ◽  
And Behavior

P. m. gracilis and P. l. noveboracensis are sympatric in southeastern Ontario and some adjacent areas. Similar in appearance, food and breeding habits, and frequently cohabiting certain forests, they may occupy identical niches, contrary to the competitive exclusion principle. A 12-week summer live-trapping study in a woodlot containing upland, mixed, and cedar forest associations showed that although most of their population characteristics were similar, their local distributions, densities, and certain behaviors differed. Noveboracensis inhabited upland forest but avoided mixed and cedar forest associations apparently because suitable refuges were lacking. The less dense population of gracilis was ubiquitous; gracilis and noveboracensis cohabited the upland forest. On release from traps noveboracensis sometimes 'froze' before darting in a zigzag manner to nearby cover, and ran up trees significantly more than gracilis, which usually ran instantly, rapidly, and directly to a more distant ground refuge. Low densities of both species reduced competition for available food and refuges. This may have facilitated cohabitation in the upland forest where differential use of ground- and tree-holes also contributed to reduction of competition and thus to compatibility. Coexistence may be transitory there; with denser populations, potential competition might be minimized by emigration of the more exploratory gracilis.

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