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Fishery Bulletin 94(3), 1996 



morphic if the frequency of the most common allele 

 did not exceed 0.95. The mean heterozygosity over 

 all loci was computed following Nei's ( 1978) unbiased 

 formula. The Hardy- Weinberg equilibrium hypoth- 

 esis was tested for all polymorphic loci by means of a 

 chi-square (X 2 ) test, by pooling genotypes when more 

 than two alleles were observed. Lavene's correction 

 for small sample size and Yates's correction for con- 

 tinuity were applied (Swofford and Selander, 19811. 

 Exact significance probabilities were calculated only 

 to check concordance with the X 2 test. 



Genetic distance (Nei, 1978) between localities was 

 computed. Also, the inbreeding coefficient, F is , and 

 the standarized variance in allelic frequencies, F ,, 

 were calculated to measure the amount of divergence 

 among subpopulations (Wright, 1965). The null hy- 

 pothesis F is -0 was tested by means of X 2 =F ;s 2 n, with 

 k(k-l) 2 degrees of freedom, where k denotes number 

 of alleles (Li and Horvitz, 1953). The null hypothesis 

 F st =0 was tested by means ofX 2 =F st 2 n, with (s-D(k-l) 

 degrees of freedom, where s denotes the number of 

 geographic localities and k the number of alleles 

 (Workman and Niswander, 1970). The heterogene- 



ity of allelic frequencies at polymorphic loci among 

 geographic localities was tested with the log-likeli- 

 hood ratio test (G-test) with Yates's correction for con- 

 tinuity (Zar, 1984). The number of migrants per gen- 

 eration was estimated by N m = (F , _I -l)/4 (Hartl, 

 1988). 



Results 



Four out of twenty-six loci were polymorphic: ODH* , 

 GPI-1*, PROT-2*, and PROT-3*. Table 2 summarizes 

 the genetic variation fish from both localities. The 

 average number of alleles per locus was 1. 19 (Mexico), 

 and 1.31 (Hawaii). The observed heterozygosity per 

 locus ranged between 0.000 and 0.341 (Table 3), with 

 a mean of 0.010 in Mexico, and 0.026 in Hawaii. The 

 mean gene diversity for the pooled data was 0.020. 

 Isocitrate dehydrogenase (IDH) revealed variation 

 in a preliminary survey. Richardson et al. (1986) 

 showed, however, that this enzyme may mimic a ge- 

 netic polymorphism where in fact it is exhibiting age- 

 related modification. The tissues samples were held 



