546 



THE CHANGING WORLD OF LIFE 



to get fertilized anyway, but there may be a great struggle among the 

 males in the battles for possession of the females. 



The seals offer a good illustration of such battles. Seals will be 

 found in groups consisting of a huge bull and a harem of quite a number 

 of cows together with the young seals, or calves. The skin of the bull 

 will probably show many scars as relics of furious battles with other 

 males for the possession of the females. When the young male seals 

 of the group become old enough to begin to take an interest in the op- 



Photo by Winchester 



Fig. 34.4. Sexual selection in the fur seal. The huge bull in the upper left has taken 

 possession of a large group of females through many victorious battles with other males. 

 A "bachelor" male looks on at the extreme right perhaps to battle for the possession 



of the females. 



posite sex they are run off by the bull. They must live a solitary ex- 

 istence until they become strong enough to capture some females of 

 their own in combat and start a harem. Since each harem may consist 

 of a large number of females, it is readily apparent that there will be 

 some males that will not succeed in the struggle. These will be the 

 weakest of the group and will thus fail to perpetuate the genes that may 

 have been responsible for their weakness. 



Even though there may be no such definitely established harem, the 

 process will be just as effective when the association is temporary. The 



