SELECTION 171 



nuptial flight. There is also sexual selec- 

 tion and germinal selection, which may be 

 conveniently considered in separate sections. 

 SELECTION. In extension of his 



theory of natural selection Darwin proposed 



a theory of sgSHgJ se.Wt.ion to apprmnt .Jpr 



p.nn- 



^ 



trasted , ^epondary sex^ph^y alters.) f a.m ilig r 

 i like TiP.RO.oolr fl.TiH P^^l stfli? airl 



There are twg modes of this sexual 

 selection : / tlie combatF^E^wee^rival males 

 and iS^pref ereiitiaL ^mating wJiere_the_Te- 

 male^chooses or s,eems to choose. 



The issue is clearer in the case of the com- 

 bats of males. For when the younger or 

 weaker candidates are killed, or expelled 

 from the herd, or left unmated, there seems 

 little reason to doubt the discriminateness 

 of the elimination. 



As to preferential mating, there is no doubt 

 that the males, especially among birds, some- 

 times show off their varied attractions, but, 

 as Wallace has consistently maintained, 

 there is very little convincing evidence that 

 the female chooses a partner out of a number 

 of suitors. Still less is there evidence that 

 she chooses because of any particular excel- 

 lence in colour or in song or in dance. In 

 some cases, however, there is evidence that 

 left. iinTpa.t^H r and 



