MIGRATION AS A FACTOR IN EVOLUTION : ITS 

 ECOLOGICAL DYNAMICS, IL 



CHARLES C. ADAMS 

 Professor of Forest Zoology, The New York State College of 

 Forestry at Syracuse Uxiversity 



III. The Migbational Factors in Evolution 

 1. Introduction 

 From the preceding discussion of the principles of ani- 

 mal activity which underlie their behavior, attention is 

 now directed in greater detail to suggestions for their 

 application to migration. Emphasis is placed upon those 

 relations which show the main causes of stress, the cycles 

 of circulation caused by diversity, and the interaction, 

 equilibrium, and adjustment operating between the vari- 

 ous systems. I have not attempted to go into detail on the 

 quantitative relations, although there is much physical 

 and some ecological data, already organized, which illus- 

 trate the method of application. There is, however, but 

 little quantitative distributional data which are at pres- 

 ent available. The elaboration of this phase is urgently 

 needed. Limiting factors retard and prevent the migra- 

 tion and ditfusion of animals; these are the ''barriers" 

 so frequently mentioned by students of geographical dis- 

 tribution. As previously mentioned, two major systems 

 or agencies are involved in this process, the animal and 

 the environment. The locomotor activity of the animal 

 is a phase of its general responses. The migrations of 

 most anirrals are therefore not different, in any impor- 

 tant features, from the ordinary daily life of the animals ; 

 that is, migrations are incidental and included within the 

 ordinary responses. Anticipating somewhat, and speak 

 ing broadly, if animal responses are of evolutionar\ value 

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