Increase in 



Number of Species 



The taxonomic intricacies of ecological communities 

 and the adaptive relationships between species em- 

 phasize the fact that a large number of evolutionary 

 patterns and processes are conditioned by the mul- 

 titudinous array of past and present species. Because 

 life presumably began from a few simple types of 

 organisms, the number of species must have in- 

 creased continuously, accompanied by survival or 

 extinction to produce the existing biota. 



Viewed in this light, the processes which lead to 

 an increase in the number of species have a unique 

 evolutionary importance. They first explain the ori- 

 gin of the great number of these evolutionary "build- 

 ing blocks" called species and in addition offer clues 

 in explaining the resultant interspecific adaptation 

 and community evolution. 



153 



