Abstract
The Lake Victoria drainage basin (LVD) in Kenya is home to ten nominal species of small barbs (Enteromius) and one of large barbs (Labeobarbus altianalis). A recent molecular study genetically characterized small barbs in this region and found evidence of introgression between certain species, complicating the taxonomy and species identification of these fishes. This study aimed to extend our understanding on the evolution of these fishes by: (1) determining whether putatively pure individuals of Enteromius cercops are found in the Kenyan LVD, as the previous study only found hybrid individuals of this species in this region; (2) testing the sister relationship between Enteromius profundus, endemic to Lake Victoria, and Enteromius radiatus, also found in Lake Victoria, which had been previously synonymized; (3) examining the phylogenetic relationships of small barbs of the Kenyan LVD with those reported from other ichthyological provinces of Africa; and (4) examining the phylogenetic relationships of Labeobarbus altianalis with other Labeobarbus species. To this end, we obtained mitochondrial Cytochrome b and nuclear Growth Hormone (GH) intron 2 gene sequences of nine Enteromius species from the LVD in Kenya, as well as cytochrome b sequences for L. altianalis. We conducted Maximum likelihood and Bayesian phylogenetic analyses to establish their evolutionary relationships in relation to many other barbs specimens from Africa. Phylogenetic analyses did not reveal instances of hybridization/introgression among the individuals sequenced by us. A sister relationship between E. profundus and E. radiatus was not found. This latter species shows instead a sister relationship with a lineage comprised of two species from West Africa. Other sister relationships between taxa from the East coast and other ecoregions from Africa are observed, suggesting that past drainage connections and vicariant events contributed to the diversification of Enteromius. Finally, only a single haplotype was recovered among the L. altianalis individuals examined, which is most similar to a specimen from Lake Edward in Uganda.
Highlights
The small, diploid, African barbs have been assigned to the tribe Smiliogastrini, and Yang et al (2015) proposed to include all of them within the genus Enteromius, the oldest available genus-group name for these fishes, even though they do not appear to correspond to a monophyletic group
They were obtained from sixteen localities in the Lake Victoria drainage area (LVD) in Kenya, which included Lake Victoria, rivers draining to the lake and associated dams [represented by triangles in Fig. 1; circles indicate the approximate location of specimens from Schmidt et al (2017) included in our analyses]
Phylogenetic reconstructions using Growth Hormone (GH) and Cytb DNA sequences are shown in Figures 2 and 3–8, respectively
Summary
Barbs constitute a significant component of the freshwater fish fauna of Africa, and represent the most species-rich group of cyprinids in this continent (Hayes and Armbruster, 2017; Leveque and Daget, 1984; Ren and Mayden, 2016; Skelton, 1988; Skelton, 1993; Skelton et al, 1991).Molecular characterization of African barbs from different regions has greatly contributed to our understanding on the diversity and evolution of these fishes (Beshera et al, 2016; De Graaf et al., 2007; Hayes and Armbruster, 2017; Muwanika et al, 2012; Ren and Mayden, 2016; Schmidt et al, 2017; Yang et al, 2015). A large dataset of DNA sequences ( of the mitochondrial Cytochrome b gene) of African barbs from different regions has accrued, providing a resource for performing phylogenetic analyses across regions, which will enhance knowledge on the systematics, evolution, and biogeographic history of this important group. They were treated as part of Barbus Cuvier and Cloquet, 1816, which included. To minimize confusion with a previous study that was conducted in the same area as the present study (Schmidt et al, 2017), hereafter we generally refer to them as ‘Barbus’ in the main text
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