Rocha-Olivares et al.: Molecular identification of luvenile Sebastes 



359 



Discussion 



Molecular identlflcation 



The genetic information encoded in the rockfish mito- 

 chondrial cytochrome b has been found useful in 

 the study of phylogenetic relationships of the spe- 

 cies in the genus Sebastes (Rocha-Olivares, 1998a). 

 The degree of genetic variability is large enough to 

 recognize diagnostic mutations characteristic of sev- 

 eral species (Rocha-Olivares, 1998a; Rocha-Olivares 

 and Vetter^). The use of this information in blind 

 tests of species identification of adult Sebastes, inde- 

 pendently determined by morphological and genetic 

 techniques, has given satisfactory results (Rocha- 

 Olivares and Lea'^). Diagnostic mutations have been 

 used to design a method of species identification 

 based on multiplex PCR (Rocha-Olivares, 1998b). In 

 our study we relied on raw DNA sequence data to 

 determine the species identity of five wild-caught 

 pelagic young of Sebastes. The very small sequence 

 divergence of their mtDNA with that of known adults 

 (ranging from zero to three bp) provided very strong 

 evidence supporting the identity of the unidentified 



Rocha-Olivares, A., and Lea, R. N. 1998. Unpubl. data. 



specimens. Moreover, the small intraspecific genetic 

 variation, indicated by the reduced standard errors 

 in Figure 1, suggests that the possibility of species 

 misidentification with our molecular approach is also 

 very small. 



Faster-evolving regions of the mtDNA have been 

 successfully used to study the genetic structure of 

 rockfish populations in both hemispheres (Rocha- 

 Olivares et al., 1999b; Rocha-Olivares and Vetter, 

 1999); therefore, it is conceivable that molecular 

 tools can also be applied intraspecifically to study, 

 for example, the relative contribution of juvenile 

 recruits from genetically differentiated populations. 



Species comparisons 



Transforming specimens of 5. constellatus and S. 

 ensifer The specimens of S. constellatus and S. 

 ensifer are remarkably similar. The meristic similar- 

 ity reflects the general overlap among species docu- 

 mented for the subgenus (Table 4; Chen, 1971, 1975). 

 The distinctly lower gill raker count for the trans- 

 forming specimen of S. constellatus, compared with 

 that of S. ensifer specimens (Table 2), matches the 

 gill raker counts of adults (Table 4; Chen, 1971). 

 Slight differences in spination between the trans- 



