Mitochondrial DNA phylogeography of the Labeobarbus intermedius complex (Pisces, Cyprinidae) from Ethiopia

Abstract

Mitochondrial DNA phylogeography of populations of the Labeobarbus intermedius complex (hexaploid barb) was investigated using 88 complete and 71 partial cytochrome b (cytb) sequences originating from 21 localities in five major drainages in Ethiopia and two localities in northern Kenya. The samples included 14 of the 15 Labeobarbus species described from Lake Tana. Discrete phylogeographic analyses of 159 cytb sequences employing Bayesian Markov Chain Monte Carlo (MCMC) simulations using Bayesian evolutionary analysis by sampling trees (BEAST) supported the monophyly of the L. intermedius complex, including the Lake Tana species. This analysis, in combination with statistical parsimony analysis, identified two mitochondrial DNA lineages within the complex. Divergence dating employing coalescent simulations suggested that the geographic split in the L. intermedius complex that led to the formation of these lineages occurred during the Pleistocene (c. 0.5 M b.p.), consistent with the timing of volcano-tectonic events postulated to have shaped the current landscape of East Africa.

Adaptive radiation of barbs of the genusLabeobarbus(Cyprinidae) in an East African river

“…Preliminary studies have documented divergence among some of these sympatric Genale barb forms (Dgebuadze & Chernova, 2012;Dimmick et al, 2001;Levin, Golubtsov, Dgebuadze, & Mugue, 2013). This is in contrast to the well-studied Labeobarbus species flock in Lake Tana, which displays no or shallow genetic divergence among sympatric forms (Beshera & Harris, 2014;de Graaf, Megens, Samallo, & Sibbing, 2010;Nagelkerke et al, 2015). The assemblage of large African barbs in the Genale River consists of species from two different genera: Labeobarbus (Labeobarbus gananensis) and Varicorhinus (Varicorhinus jubae).…”

Adaptive radiation of barbs of the genusLabeobarbus(Cyprinidae) in the East African river

“…Preliminary studies have documented genetic divergence among some of these sympatric Genale barb forms (Dimmick et al 2001;Levin et al 2013). This is in contrast to the well-studied Labeobarbus species flock in Lake Tana, which displays no or shallow genetic divergence among sympatric forms (de Graaf et al 2010;Beshera and Harris 2014;Nagelkerke et al 2015). The assemblage of large African barbs in the Genale River consists of species from two different genera: Labeobarbus (L. gananensis) and Varicorhinus (V. jubae).…”

Shallow genetic divergence and species delineations in the endemic Labeobarbus species flock of Lake Tana, Ethiopia

“…Since this study inferred a very recent origin of the Lake Tana labeobarb species, the incongruence was explained by incomplete lineage sorting. This was confirmed by Beshera & Harris (2014) in their study on the L. intermedius of Ethiopia, including Lake Tana; they also did not find a relationship between mtDNA differentiation and species delineations in the Lake Tana flock, while they did find separate genetic lineages between different, geographically separate Ethiopian populations. Validation of the species status and inference of the phylogenetic history of the Labeobarbus spp.…”

“…: +31 317 483940; email: Leo.Nagelkerke@wur.nl 1191 most probably monophyletic and young; adaptive radiation and speciation most likely occurred during the past 10 000-25 000 years. This was based on the low sequence differentiation in mtDNA (de Graaf et al, 2010a;Beshera & Harris, 2014) and corroborating geological evidence (Lamb et al, 2007). The species probably radiated from an ancestral riverine benthivorous species resembling Labeobarbus intermedius (Rüppell 1835) that is common in the Ethiopian highlands (Banister, 1973) and most likely still present along the shores of Lake Tana (Nagelkerke et al, 1994;.…”