56 



CORA D. REEVES. 



3. Sexual Selection. 



The evidence has been already presented to show that in Ethe- 

 ostoma the bright males are most frequently successful in spawn- 

 ing. I would be justified, from some days' observations, in claim- 

 ing evidence for sexual selection in the Darwinian sense, a selec- 

 tion of the brilliant males by the females. For my notes show 

 that the females, although followed in their course by small 

 males, often go directly from the holding of one large male to 

 that of another. They thus appear to consciously neglect or 

 repel the smaller and more insistent males and to give preference 

 to the larger ones. On the other hand my observations show 

 that the females spawn with whatever male happens to be pres- 

 ent. Even in the holding of a large male the spawning is some- 

 times with a small one while the large one is driving away 

 intruders. Hence, although the brilliant males are more success- 

 ful in pairing than the duller males, yet I find no evidence that the 

 female chooses them. What appears to be a choice of males is 

 probably in reality a choice of spawning places. This subject 

 has been discussed under the heading " Origin of Nest Building 

 Habits." We then find no sufficient evidence in the behavior of 

 the female that she so discriminates between males as to give 

 to any color or color pattern selectional value in the sense of 

 Darwin (1883). If this be true, the displays of color and move- 

 ment (by the male before the female) result, not in a selection 

 by the female of particular males but only in an increase of the 

 general state of nervous excitement among the participating 

 fishes. (Cf. for birds Hacker, 1900.) It does not appear that the 

 female exercises any choice either conscious or unconscious 

 based on color or movement. 



The only form of selection that appears to be present is that 

 which arises from the rivalry of the males and results in the limi- 

 tation of the breeding activities of the smaller males. Since the 

 smaller males undoubtedly breed when older the case is merely 

 one of "seniores priores." The preponderance of the older males 

 in the breeding cannot have resulted in the evolution of secondary 

 sexual characters. This could have come about, by selection, 

 only through the preponderance in the breeding of males having 

 certain secondary sexual characters not possessed by other males. 



