Population‐structure and genetic diversity in a haplochromine fish cichlid of a satellite lake of Lake Victoria

Abstract

The ∼ ∼ ∼ ∼ 500 species of the cichlid fish species flock of Lake Victoria, East Africa, have evolved in a record-setting 100 000 years and represent one of the largest adaptive radiations. We examined the population structure of the endangered cichlid species Xystichromis phytophagus from Lake Kanyaboli, a satellite lake to Lake Victoria in the Kenyan Yala wetlands. Two sets of molecular markers were analysed -sequences of the mitochondrial control region as well as six microsatellite loci -and revealed surprisingly high levels of genetic variability in this species. Mitochondrial DNA sequences failed to detect population structuring among the three sample populations. A model-based population assignment test based on microsatellite data revealed that the three populations most probably aggregate into a larger panmictic population. However, values of population pairwise F ST indicated moderate levels of genetic differentiation for one population. Eleven distinct mitochondrial haplotypes were found among 205 specimens of X. phytophagus , a relatively high number compared to the total number of 54 haplotypes that were recovered from hundreds of specimens of the entire cichlid species flock of Lake Victoria. Most of the X. phytophagus mitochondrial DNA haplotypes were absent from the main Lake Victoria, corroborating the putative importance of satellite lakes as refugia for haplochromine cichlids that went extinct from the main lake in the last decades and possibly during the Late Pleistocene desiccation of Lake Victoria.

Pleistocene desiccation in East Africa bottlenecked but did not extirpate the adaptive radiation of Lake Victoria haplochromine cichlid fishes

“…Yet, the mechanisms of speciation by which they arose (e.g., [1][2][3][4][5] and the age of the adaptive radiation (e.g., 6-9) are still debated vigorously. Knowledge about both age and evolutionary history are important because the amazing variety of body shapes, assortment of coloration, behavioral diversity, and degree of ecological specialization have made African haplochromine cichlids a prime example for the study of evolution generally and adaptive radiations specifically (e.g., [10][11][12][13][14][15].…”

Morphological variations of wild populations of Nile tilapia (Oreochromis niloticus) living in extreme environmental conditions in the Kenyan Rift-Valley

“…Within these three East African Lakes, some cichlid species went through rapid morphological diversification and speciation, leading to formation of many new species within a few thousand generations (Sage et al 1984;Meyer et al 1990;Owen et al 1990). In Lake Victoria for instance, the radiation of monophyletic haplochromine species occurred within a geologically short time of about 750,000 years and resulted to the emergence of approximately 500 cichlid species (Greenwood 1984;Abila et al 2004;Kerschbaumer and Sturmbauer 2011). Additionally, evolutionary older cichlid assemblages of Lake Tanganyika have shown the highest degree of morphological differentiations (Salzburger et al 2002).…”

Comparative Phylogenetic Analyses of the Adaptive Radiation of Lake Tanganyika Cichlid Fish: Nuclear Sequences Are Less Homoplasious But Also Less Informative Than Mitochondrial DNA

“…Due to the extreme pace of lineage formation and the relatively young age of at least some of these species flocks, the analysis of commonly used markers such as mitochondrial DNA (mtDNA) sequences was still not able to resolve all phylogenetic issues. For example, the persistence of ancestral polymorphisms as a consequence of incomplete lineage sorting has been suggested to occur, in particular, in the extremely young and therefore closely related cichlid species of Lakes Malawi (Moran and Kornfield 1995) and Victoria (Nagl et al 1998;Verheyen et al 2003;Abila et al 2004). Recent attempts to overcome this problem include the analysis of AFLP markers, which have successfully been applied to a subset of species from Lakes Malawi and Victoria (Albertson et al 1999;Allender et al 2003;Seehausen et al 2003).…”