DIaz-Jaimes and Uribe-Alcocer; Allozyme and RAPD variation in Thunnus albacares 



771 



126° 



119° 



28° 



21° 



7° - 



OCY 



"O 



WRE 



€ 



126° 



19° 



Revillagigedo ," 

 Islands 



Gpi- F alleles 



700 



Figure 1 



Thunnus albacares. Location of sampling sites, dates, and sample sizes, and Gpi-F* gene frequencies of eastern Pacific 

 yellowfin tuna. The sites are as follows: OCY = out of CYRA area; WRE = west of the Revillagigedo Islands; NCL = 

 North Clipperton islands; SCL = South Clipperton Islands; MCH = Michoacan; QUE = Guerrero; COL = Colima; CSL = 

 Cape San Lucas; NAY = Nayarit; GC = Gulf of California. Symbols are • coastal, A intermediate,  offshore. 



a final cycle of 15 min. at 72°C. Optimal DNA concentra- 

 tions for amplification were determined by testing several 

 dilutions, one of which was taken as the standard for every 

 subsequent amplification. 



Amplified fragments were resolved by electrophoresis in 

 1.5% agarose gels (Sigma Chemicals) for 3 to 4 h. at 90 mA 

 (100 V). A lOObp DNA Ladder (GibcoBRL, Gaithersburg, 

 MD, 15628-019) was used as size standard. After electro- 

 phoresis, gels were stained with ethidium bromide and 

 photographed in a UV light transilluminator. 



Data analysis 



Allelic frequencies, test of conformity of genotype distribu- 

 tions with Hardy-Weinberg, and heterozygous deficit were 

 determined by using Genepop version 3.3 (Raymond and 

 RoussetM. Homogeneity of allozyme and RAPD allele fre- 

 quencies was evaluated by using the exact probability test 



(Raymond and Rousset, 1995) consisting of a contingency 

 analysis for every polymorphic locus and an estimation 

 of their probability values by the combined probability 

 of Fisher (Sokal and Rohlf, 1995) as implemented in the 

 TFPGA program (Miller^). Pairwise comparisons were 

 conducted to determine allele frequency differences among 

 samples in order to define sources of variation. Based on 

 the longitudinal differentiation pattern observed by Ward 

 et al. (1994) and the morphological latitudinal differences 

 within eastern Pacific samples reported by Schaefer (1991) 



1 Raymond, M. L., and F. Rousset. 1995a. GENEPOP (ver- 

 sion 1.2): population genetics software for exact tests and 

 ecumenicist. J. Heredity 86:248-249. 



2 Miller, M. P. 1997. Tools for genetic populations analyses 

 (TFPGA) 1.3: a windows program for the analysis of allozyme 

 and molecular population genetic data, 29 p. Computer 

 software distributed by the author at http://bioweb.usu.edu/ 

 mpmbio. 



