Nest Associates of Nocomis leptocephalus 85 



prevent association in at least some species of nest builders. The 

 relationship could also be commensal, with the reproductive success of 

 the nest builder remaining unaltered while that of the associates increases. 



Carr (1942) observed eggs of lake chubsucker, Erimyzon sucetta, in 

 the nests of largemouth bass, Micropterus salmoides, and eggs of golden 

 shiner, Notemigonus crysoleucas, in the nests of spotted sunfish, Lepomis 

 punctatus (Valenciennes) (Carr 1946). She compared these relationships 

 to the parasitism that occurs between the cowbird and its hosts (Carr 

 1942). However, her data for the chubsucker/ largemouth bass relation- 

 ship suggest that instead of a parasitic relationship, in which the host's 

 reproductive success is reduced, a mutually beneficial relationship occurs 

 (McKaye 1981). Carr (1942) found 22 largemouth bass nests of which 5 

 had chubsucker eggs. Four of these 5 nests were successful (produced 

 fry), while only 1 of 14 nests without chubsucker eggs was successful 

 (Carr 1942, McKaye 1981). The reproductive success of the largemouth 

 bass was apparently higher in nests with chubsuckers eggs, a finding that 

 suggests a mutually beneficial relationship (assuming chubsucker eggs 

 laid outside nests would not survive). Whether the chubsuckers chose to 

 lay their eggs in largemouth bass nests that would have been the most 

 successful regardless of the presence of chubsucker eggs is unknown. 



Goff (1984) discovered longnose gar, Lepisosteus osseus, eggs in 10 

 of 69 smallmouth bass, Micropterus dolomieu Lacepede, nests. Of the 

 nests with gar eggs, 60% were successful, whereas only 32% of the n^sts 

 without gar eggs were successful. Goff (1984) also showed that clutches 

 of gar eggs were the most successful when they were intermingled with 

 smallmouth bass eggs in the nest, and that eggs did not survive outside 

 nests. These observations suggest that both species benefit from this 

 relationship. 



Results indicating that nests builders and associates both benefit 

 from the association support the hypothesis of McKaye and McKaye 

 (1977) in which natural selection is the driving force behind the evolution 

 of interspecific brood care in fishes, and fishes that care for unrelated 

 young have greater reproductive success. This hypothesis suggests that 

 relationships such as nest association are mutually beneficial. 



My future work is aimed at understanding the nature of the 

 relationship between nest associates and their hosts. Is this a mutualistic, 

 parasitic, or commensal relationship? Answering that question should 

 lead to a better understanding of the evolution of the nest-associate 

 strategy. 



ACKNOWLEDGMENTS.— This research was supported in part by 

 a grant-in-aid of research from Sigma Xi, The Scientific Research 

 Society. L. M. Page and P. A. Ceas assisted in the field. I thank C. A. 

 Mayer and P. E. Jarrell for critical review of the manuscript. 



