664 



ORGANIC EVOLUTION 













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Fig. 26-8. A case of protective coloration. Notice how this beetle blends with the bit of bark on which it is resting. 



produce malformed animals that soon die, 

 or again the number of offspring may be 

 small. These incompatibilities noted now, 

 after several hundred more generations, 

 may perhaps become so great as to place a 

 strict genetic barrier between certain vari- 

 eties of dogs alive today, thus inaugurating 

 a new species. If that happens, man will 

 have created a new species and thus con- 

 trolled evolution under his own guidance. 

 We must conclude, therefore, that in the 

 domestication process, man has within his 

 grasp the very mechanism by which evolu- 

 tion proceeds. 



THE END RESULT OF EVOLUTION: 

 ADAPTATION 



Out of all this should come animals re- 

 markably adapted to their environment but, 

 as we have already seen, this is not com- 



pletely so. In spite of the rather careless 

 way in which most animals are keyed to 

 their environments, certain examples of 

 adaptation forever intrigue the naturalist 

 and the layman. Among these, color adapta- 

 tions are particularly interesting. 



The matter of camouflage is an important 

 factor in survival and is used almost uni- 

 versally by animals. Such concealing or pro- 

 tective coloration has been selected for, 

 until the outer coverings of some animals 

 match their background astoundingly well 

 (Fig. 26-8). Most animals, particularly 

 those that fly or swim, are dark on the dor- 

 sal side and white or lighter in color on the 

 ventral side. Thus potential predators from 

 beneath looking up will be less apt to see 

 them because they blend with the sky and 

 those from above would experience the 

 same difficulty because of blending with 

 the darker earth or stream bottom. Other 



