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African Journal of Aquatic Science

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Population genetic structure of the sidespot barb, Barbus neefi, from the north-eastern escarpment, South Africa

GD Engelbrecht, PFS Mulder, JS Engelbrecht

Abstract


Allozyme analysis was used to determine patterns of genetic variation within and between populations of Barbus neefi. The products of 29 loci were analysed, with 17 loci being monomorphic in all populations. The genetic variability estimates compared well with values reported in the literature. The percentage of polymorphic loci (0.95 criterion) ranged from 020.69% and average expected heterozygosity from 0.0040.069. Headstream populations generally revealed lower genetic variability than populations in low lying areas, which emphasizes the importance of conserving headstream populations. Fixed allele mobility differences were observed at the MPI-1 protein coding locus between the Selons River population and the other populations. The measures of genetic differentiation as assessed by F-statistics, the effective number of migrants per generation and Nei's unbiased genetic distance consistently separated the Selons River population from the rest. Nevertheless, these estimates all fell within the range considered for conspecific populations. There was also a clear genetic division between populations from north and south of the Olifants River. The three populations from the Dorps, Spekboom and Blyde Rivers (Limpopo River system) and the population from the Crocodile River (Incomati River system) showed negligible genetic differentiation. Human-assisted transfer of populations may be responsible for this close similarity.


Keywords: Barbus neefi; allozymes; interspecific genetic differentiation; electrophoresis


(Afr J Aqua Sci: 2002 27(2): 159-169)



http://dx.doi.org/10.2989/16085914.2002.9626587
AJOL African Journals Online