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

Abstract

To assess whether the species distinctions of Lake Tana's Labeobarbus spp. are supported by genetic information, microsatellite markers were used. A total of 376 Labeobarbus spp., belonging to 24 populations of 11 species from three regions of the lake (north, south and east), were sampled. Eight microsatellite markers were analysed. In general, differences between conspecific populations were smaller than differences between populations of different species. For six species, conspecific populations from different regions in the lake were consistently more similar than populations of other species from the same region. For four species this was not the case, while for one species two populations were similar, but different from the third population. River-spawning species appeared to be more distinct than presumed lake spawners. On the species level, there was a significant correlation between genetic and morphological differentiation, especially in morphological aspects associated with ecological functioning. This suggests that genetic differentiation arose together with adaptive radiation, although the overall genetic differentiation among the Lake Tana Labeobarbus spp. is small.

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).…”

Internal sources of infraorbital series and lateral line scale count variability in six Labeobarbus species composing the Lake Tana (Ethiopia) species flock

“…Revealed differences in distributions may be a consequence of incipient reproductive isolation among Tana barbs species. Such isolation is also supported by the shallow differences between species in microsatellite markers (Nagelkerke et al., ).…”

“…In accordance with the geological data of the last lake desiccation, the proposed age of this flock is less than 15,000 years. The young age of the flock is also supported by genetic analysis (Beshera & Harris, ; de Graaf, Megens, Samallo, & Sibbing, ; Nagelkerke et al., ).…”