Genetic divergence among morphotypes of Lake Tana (Ethiopia) barbs

Abstract

The genus Barbus is a paraphyletic assemblage that includes three different ploidy levels: diploid, tetraploid and hexaploid. 'B.' inhmdius, which inhabits Lake Tana (Ethiopia), is a hexaploid taxon that forms a 'species flock' consisting of at least 14 morphotypes. Thirtyone presumptive allozymic loci were analysed in a large sample of 'B.' intermedius. No diagnostic loci were observed between the morphotypes, but substantial differences in allele frequencies were found. One morphotype, Acute, differs significantly from the others. The presence of this genetic differentiation within the lake strongly suggests that the morphotypes are diverging lineages. Because of some parallel characteristics with cichlid species flocks, we put forward the hypothesis that the morphotypes of barbs in Lake Tana represent a species flock that originated via sympatric speciation with more rapid morphological than molecular differentiation. If the differentiation and the reproductive isolation are real, it is probable that the morphotypes already are or will soon reach the status of species. 0 1998 The Linnean Society of London ADDITIONAL KEY W0RDS:species flocksympatric speciationallozymes -Barbus.

Reproductive isolation among deep‐water cichlid fishes of Lake Malawi differing in monochromatic male breeding dress

“…By contrast, ecological selection is believed to have played a major role in the divergence of other lake fish radiations where sympatric speciation is implicated, including cichlid fishes in small tropical lakes in Nicaragua (Barluenga et al . 2006) and Cameroon (Schliewen & Klee 2004), as well as salmonids, sticklebacks and whitefish in postglacial lakes (Schluter 1996) and cyprinids in Lake Tana (Berrebi & Valiushok 1998). Thus, while it might be premature to rule out sympatric speciation of Diplotaxodon driven either by ecological or sexual selection, it might also be fruitful to consider whether allopatric divergence in female preferences and male body patterns may have evolved during periods of restricted gene flow between geographically separated populations.…”

Morphometry and DNA barcoding reveal cryptic diversity in the genus Enteromius (Cypriniformes: Cyprinidae) from the Congo basin, Africa

“…Based on ploidy level, Barbus s.l. has been divided into three groups: diploids (2n = 48 or 50), tetraploids (2n = 100) and hexaploids (2n = 148-150) (Agnèse et al 1990;Oellerman & Skelton 1990;Rab et al 1995;Berrebi & Valiushok 1998). The phylogeny of some of these groups has been examined (e.g., Agnèse et al 1990;Tsigenopoulos et al 2010), and a number of studies suggested to split Barbus s.l.…”

Interactions among quantitative traits in the course of sympatric speciation

“…Third, reproductive isolation must be due to differences in not too many loci. Therefore, genetic analysis of morphological, ecological and behavioural differences between sympatric species of a very recent origin [1][2][3][4] can be used to test this scenario. …”