238 



The Evolution of Communities 



therefore likely that this aspect of community evolution began in 

 simple aggregations of species, in fact as soon as one group of 

 organisms began feeding on another. 



Certain types of protective devices must have followed others. 

 The secretion of disagreeable substances must have preceded and 

 established selection pressures for the differential survival of con- 

 spicuously marked mutants, which would be the forerunner of 

 warning coloration. Only when warning colors had evolved in some 

 species would selection pressures have been set up for other spe- 

 cies to evolve patterns mimicking these protective schemes (Fig. 

 102). Likewise no selection pressures would have existed leading 

 to the evolution of stick-like or leaf-like animals until sticks and 

 leaves themselves had evolved. 



It seems certain, therefore, that not only did selection pressures 



(a) 



(b) 



(c) 



(d) 



(e) 



(f) 



(g) 



(h; 



Fig. 102. Warning coloration and mimicry in Neotropical insects. In each 

 of these fonr pairs of insects the species to the left is a distasteful lycid beetle 

 exhibiting warning coloration, and the species to the right is a cerambycid 

 beede mimicking a lycid species living in the same community. Lycidae: (a), 

 (c), (e), (g), Calopteron species. Cerambycidae: (b), (h), Fterophtus spe- 

 cies, (d) Lijcidola. (f) Lycomimu.s. (After Linsley.) 



