Genetic isolation and morphological divergence mediated by high-energy rapids in two cichlid genera from the lower Congo rapids

<p>Abstract</p> <p>Background</p> <p>It is hypothesized that one of the mechanisms promoting diversification in cichlid fishes in the African Great Lakes has been the well-documented pattern of philopatry along shoreline habitats leading to high levels of genetic isolation among populations. However lake habitats are not the only centers of cichlid biodiversity - certain African rivers also contain large numbers of narrowly endemic species. Patterns of isolation and divergence in these systems have tended to be overlooked and are not well understood.</p> <p>Results</p> <p>We examined genetic and morphological divergence among populations of two narrowly endemic cichlid species, <it>Teleogramma depressum </it>and <it>Lamprologus tigripictilis</it>, from a 100 km stretch of the lower Congo River using both nDNA microsatellites and mtDNA markers along with coordinate-based morphological techniques. In <it>L. tigripictilis</it>, the strongest genetic break was concordant with measurable phenotypic divergence but no morphological disjunction was detected for <it>T. depressum </it>despite significant differentiation at mtDNA and nDNA microsatellite markers.</p> <p>Conclusions</p> <p>The genetic markers revealed patterns of philopatry and estimates of genetic isolation that are among the highest reported for any African cichlid species over a comparable geographic scale. We hypothesize that the high levels of philopatry observed are generated and maintained by the extreme hydrology of the lower Congo River.</p>

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• Colour variation in cichlid fish: Developmental mechanisms, selective pressures and evolutionary consequences · 2013

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