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African Journal of Aquatic Science

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Phylogeography of the African catfish, Chrysichthys maurus (Valenciennes, 1839)

J-F Agnèse

Abstract


Polymorphism at 19 allozyme loci was studied in 227 individuals of the catfish, Chrysichthys maurus (Valenciennes, 1839), collected from ten populations representing nine different river basins in west Africa. Eleven of the loci studied were polymorphic. Analysis showed that populations clustered according to their geographical origin: eastern populations close to the root represented by a population of a closely related species (C. auratus); then populations from the centre of the species' range, followed by the more western populations. Networks observed, regression of genetic distances versus geographical distances, results of the Mantel test as well as the apomorphic status of two alleles suggested that the genetic differentiation corresponds to an isolation by distance model. These results strongly suggest that the populations initially occurred in the lagoons and rivers of Ivory Coast and from here spread to the western part of the species' range by progressively colonising basins from east to west.


Keywords: Siluriformes; allozyme; isolation by distance; biogeography; west Africa



(Afr J Aqua Sci: 2003 28(2): 169-174)



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