DMA 



Deoxyribonucleic acid, the chief constituent of chromo- 

 somes which apparently is the material constituting the 

 genes. 



Doldrums 



The equatorial belt of calm or light variable winds, low 

 atmospheric pressure, lying between two trade- wind belts. 



Dolomite 



A rock containing a high percentage of calcium and mag- 

 nesium carbonates. 



Domatium 



A small structure on certain plants, particularly on the 

 leaves, which forms a shelter for organisms such as insects 

 or fungi. 



Dominance Classes 



The five groups of species in a classification based on 

 Coverage (q. v.). 



Dominance, Ecologic 



The condition in communities or in vegetational strata 

 in which one or more species, by means of their number, 

 coverage, or size, have considerable influence or control upon 

 the conditions of existence of associated species. 



Dominance, Genetic 



The influence exerted by a dominant character or Allele 

 e.g., redness of petals in certain flowers is dominant over 

 white, cf. Recessive. 



Dominance, Social 



The determination of the behaviour of one or more ani- 

 mals by the aggressive behaviour or otherwise of other indi- 

 viduals, resulting in the establishment of a social Hierarchy. 



Dominant (Character) 



See Allele. 



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