COMPETITION 161 



to be omnivorous. However, the rivalry among squirrels and nut- 

 crackers for pine seeds may be intense. In other words, similarity in 

 behavior, that is in life habits, may often overrule life form. 



Since the term itself denotes common seeking, there is no further 

 competition without a proper degree of density or crowding, and the 

 effects increase more or less geometrically with the crowding. Com- 

 petition thus becomes peculiarly a community function, and hence is 

 necessarily affected by the manner of aggregation, the structure in 

 terms of layers and minor communities, and the developmental stage 

 attained. 



Course and Outcome of Competition. As with other phases of 

 competition, the absence of detailed studies renders it impossible to 

 trace more than its general course in animal communities (cf. Forbes, 

 1887; Howard, 1920; Allee, 1931, a). On the other hand, plants and 

 plant communities have received considerable attention from this 

 approach, and the nature and course of this function are fairly well 

 understood, as is shown later in this section. The general stages of 

 the processes are epitomized in the outcome, which is represented by 

 dominance in varying degree for the successful competitors and by 

 subordination or elimination for the unsuccessful ones. Subordination 

 may result in subdominance to produce the layers of forest and thicket 

 or the aspect societies of grassland, or it may lead to suppression in 

 the guise of secondary species and communities. When suppression 

 reaches the extreme of elongation or dwarfing, it passes into elimina- 

 tion, which constitutes a universal feature of succession. 



A similar series of competition phenomena is to be found in animal 

 communities, though in the absence of dominance on land it is less 

 pronounced and visible. It is readily seen in the leadership of old 

 males in polygamous herds, in the culls of broods and the runts of 

 litters, and in such social phenomena as the "peck order" of fowls. 

 It is exemplified in some measure in the drawing of territorial limits 

 by many species, but usually reaches its most characteristic expres- 

 sion among the sessile constituents of marine communities. 



Reduction or Evasion of Competition. Competition may be reduced 

 in intensity or more or less completely avoided in a variety of ways. 

 It is obvious that such results may be secured by a reversal of the 

 relations or conditions that promote competition, such as similarity of 

 life form or life habit, close spacing, etc. The greater the variety in 

 life forms or behavior, the larger the number of species that can exist 

 side by side in essential harmony. This is well exemplified by sub- 

 ordination, as a result of which a large number of shrubs and herbs 

 may thrive under a forest canopy, or a wealth of forbs flourish amid 



