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Colour-assortative mating among populations of Tropheus moorii, a cichlid fish from Lake Tanganyika, East Africa.

ABSTRACT: The species flocks of cichlid fishes in the East African Lakes Tanganyika, Malawi and Victoria are prime examples of adaptive radiation and explosive speciation. Several hundreds of endemic species have evolved in each of the lakes over the past several thousands to a few millions years. Sexual selection via colour-assortative mating has often been proposed as a probable causal factor for initiating and maintaining reproductive isolation. Here, we report the consequences of human-mediated admixis among differentially coloured populations of the endemic cichlid fish Tropheus moorii from several localities that have accidentally been put in sympatry in a small harbour bay in the very south of Lake Tanganyika. We analysed the phenotypes (coloration) and genotypes (mitochondrial control region and five microsatellite loci) of almost 500 individuals, sampled over 3 consecutive years. Maximum-likelihood-based parenthood analyses and Bayesian inference of population structure revealed that significantly more juveniles are the product of within-colour-morph matings than could be expected under the assumption of random mating. Our results clearly indicate a marked degree of assortative mating with respect to the different colour morphs. Therefore, we postulate that sexual selection based on social interactions and female mate choice has played an important role in the formation and maintenance of the different colour morphs in Tropheus, and is probably common in other maternally mouthbrooding cichlids as well.

SUBMITTER: Salzburger W

PROVIDER: S-EPMC1560039 | biostudies-literature | 2006 Feb

REPOSITORIES: biostudies-literature

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Colour-assortative mating among populations of Tropheus moorii, a cichlid fish from Lake Tanganyika, East Africa.

Salzburger Walter W Niederstätter Harald H Brandstätter Anita A Berger Burkhard B Parson Walther W Snoeks Jos J Sturmbauer Christian C

Proceedings. Biological sciences 20060201 1584

The species flocks of cichlid fishes in the East African Lakes Tanganyika, Malawi and Victoria are prime examples of adaptive radiation and explosive speciation. Several hundreds of endemic species have evolved in each of the lakes over the past several thousands to a few millions years. Sexual selection via colour-assortative mating has often been proposed as a probable causal factor for initiating and maintaining reproductive isolation. Here, we report the consequences of human-mediated admixi ...[more]

PMID: 16543167

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Project description:BACKGROUND: Cichlid fishes are notorious for their wealth of intra- and interspecific colour pattern diversity. In Lake Tanganyika, the endemic genus Tropheus represents the most impressive example for geographic variation in the pattern and hue of integument colouration, but the taxonomy of the over 100 mostly allopatric colour morphs remains to a large degree unresolved. Previous studies of mitochondrial DNA sequence data revealed polyphyly of the six nominally described species and complex phylogeographic patterns influenced by lake level fluctuations and population admixture, and suggested the parallel evolution of similar colour patterns in divergent evolutionary lineages. A gene tree of a rapidly radiating group may be subject to incomplete and stochastic lineage sorting, and to overcome this problem we used multi-locus, nuclear AFLP data in comparison with mtDNA sequences to study diversification, migration and introgression in Tropheus colour morphs in Lake Tanganyika. RESULTS: Significant incongruence between phylogenetic reconstructions from mitochondrial and AFLP data suggested incomplete sorting of mitochondrial haplotypes as well as frequent introgression between differentiated lineages. In contrast to the mitochondrial phylogeny, the AFLP phenogram was largely congruent with species classifications, colour pattern similarities, and in many cases also with the current geographic distribution of populations, and did not produce evidence of convergent colour pattern evolution. Homoplasy in the AFLP data was used to identify populations that were strongly affected by introgression. CONCLUSION: Different evolutionary processes were distinguished by the combination of mitochondrial and AFLP data. Mitochondrial phylogeographic patterns retained signals of large-scale migration events triggered by historical, major lake level fluctuations, whereas AFLP data indicated genetic cohesion among local groups of populations resulting from secondary contact of adjacent populations in the course of the more frequently occurring, minor lake level fluctuations. There was no support for the parallel evolution of similar colour patterns in the AFLP data. Genetic signatures of introgression and hybridisation detected in several populations suggest that lake level fluctuations drove the stunning diversification of Tropheus morphs not only through population fragmentation, but also by promoting hybridisation between differentiated morphs in secondary contact.

Dataset Information

Colour-assortative mating among populations of Tropheus moorii, a cichlid fish from Lake Tanganyika, East Africa.

Publications

Colour-assortative mating among populations of Tropheus moorii, a cichlid fish from Lake Tanganyika, East Africa.

Similar Datasets

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