of Lake Victoria—An analysis based on SINEs and mitochondrial DNA
Semvua I. Mzighani a,b, Masato Nikaido a, Miyuki Takeda c, Ole Seehausen d,e, Yohana L. Budeba f,
Benjamin P. Ngatunga f, Egid F.B. Katunzi b, Mitsuto Aibara a, Shinji Mizoiri a, Tetsu Sato g,
Hidenori Tachida c, Norihiro Okada
More than 500 endemic haplochromine cichlid species inhabit Lake Victoria. This striking species diversity is
a classical example of recent explosive adaptive radiation thought to have happened within the last
∼15,000 years. In this study, we examined the population structure and historical demography of 3 pelagic
haplochromine cichlid species that resemble in morphology and have similar niche, Haplochromis
(Yssichromis) laparogramma, Haplochromis (Y.) pyrrhocephalus, and Haplochromis (Y.) sp. “glaucocephalus”.
We investigated the sequences of the mitochondrial DNA control region and the insertion patterns of short
interspersed elements (SINEs) of 759 individuals. We show that sympatric forms are genetically
differentiated in 4 of 6 cases, but we also found apparent weakening of the genetic differentiation in areas
with turbid water. We estimated the timings of population expansion and species divergence to coincide
with the refilling of the lake at the Pleistocene/Holocene boundary. We also found that estimates can be
altered significantly by the choice of the shape of the molecular clock. If we employ the nonlinear clock
model of evolutionary rates in which the rates are higher towards the recent, the population expansion was
dated at around the event of desiccation of the lake ca. 17,000 YBP. Thus, we succeeded in clarifying the
species and population structure of closely related Lake Victoria cichlids and in showing the importance of
applying appropriate clock calibrations in elucidating recent evolutionary events.
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