Aliogenic Succession 



The kind of succession (q. v.) in which one kind of 

 community replaces another because of a change in the 

 environment which was not produced by the plants them- 

 selves, e.g., decrease in soil moisture by improved drainage, 

 cf. Autogenic succession. 



Allometry 



Relationships in the evolutionary development of organs 

 or other characters of organisms which may bring about 

 disharmony, e.g., disproportionate development of antlers 

 and neck muscles of deer or moose. 



Allopatric 



Refers to organisms originating in or occupying different 

 geographic areas, cf. Sympatric. 



Allopolyploid 



A polyploid (q. v.) which originated by the addition of 

 unlike sets of chromosomes, cf. Autopolyploid, Amphiploid. 



Allopelagic 



Refers to organisms occurring at any depth in the sea. 



Allotrophic 



Refers to lakes or ponds that receive organic material 

 by drainage from the adjacent land. cf. Autotrophic. 



Alluvial Fan 



A fan-shaped deposit of sand, gravel, and fine material 

 from a stream where its gradient lessens abruptly. 



Alluvial Soil 



Soil that has developed from transported and relatively 

 recently deposited material (alluvium), characterized by 

 little or no modification of the original material by soil- 

 forming processes. 



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