Multiple repeated patterns of adaptive radiation were revealed in cyprinid fish inhabiting the compact geographic region of the ethiopian Highlands. We found four independently evolved radiations in the evolutionary hexaploid (2n = 150) Labeobarbus lineage based on matrilineal relationships of >800 individuals. Each radiation displayed similar patterns of mouth phenotype diversification, and included ecomorphs/species of the generalized, lipped, scraping (one or two), and large-mouthed (one to three) types. All radiations were detected in geographically isolated rivers, and originated from different ancestral populations. This is the first documented case in which numerous parallel radiations of fishes occurred-via different ways-in a riverine environment. Some radiations are very recent and monophyletic, while others are older and include ecomorphs that originated in separate mini flocks and later combined into one. The diversification bursts among Ethiopian Labeobarbus were detected in the mid-upper reaches of rivers (1050-1550 m above sea level), which likely offer ecological opportunities that include diverse habitats yet poor fauna (i.e. lower competition and relaxed selection). this promising example of parallel evolution of adaptive radiation warrants further investigation.In the pioneering work on South African cichlids and catfishes, Joyce et al. 21 and Day et al. 19 suggested that the riverine flocks are remnants of radiations that emerged in a paleolake. This suggestion is corroborated by the finding of the Lake Tanganyika endemics beyond the lake basin 33 . While some riverine radiations clearly have lacustrine origins, it is likely that other riverine radiations originate from sources other than lakes. Hence, we aimed to test whether the same environmental factors that trigger lacustrine radiation can also act in rivers.In general, the main prerequisites for adaptive radiation are: (1) environmental stability for evolutionarily significant periods (starting from thousands of years ago); and (2) physical isolation from the river drainages harboring diverse fish faunas 15,20,31 . The latter serves a dual purpose: first, it provides the ecological opportunities for niche divergence at the initial stages of radiation, and later it prevents the extinction of diverged forms caused by competition with highly specialized species from other systematic groups. These processes can operate in specific and rather rare parts of the riverine network. For example, the segment of the Genale River that harbours the radiating assemblage of distinct forms of the Labeobarbus is situated in the apparently old canyon, isolated by the Baratieri Falls from the lower reaches of the river system and characterized by the depauperate fish fauna 20 .If the fish radiations in rivers are similar to the evolutionary phenomena experienced in lakes, they should display similar evolutionary patterns. It is well known that adaptive radiations are often repeatable in different organisms as exemplified from spiders 34 , fish 35 , and liz...

The phylogenetic relationships and the phylogeography of seven species of Caucasian barbels of the genus Barbus s. str. were studied based on extended geographic coverage and the use of mtDNA and nDNA markers. Based on the 26 species studied, matrilineal phylogeny of the genus Barbus is composed of two clades: a) West European clade, and b) Central and East European clade. The latter comprises two subclades: b1) Balkanian subclade, and b2) Ponto-Caspian subclade, which includes 11 lineages mainly from Black and Caspian Sea drainages. Caucasian barbels are not monophyletic and are subdivided into two groups. The Black Sea group encompasses species from tributaries of the Black Sea, including the reinstalled B. rionicus, except for B. kubanicus. The Caspian group includes B. ciscaucasicus, B. cyri (with B. goktschaicus, which might be synonymized with B. cyri), B. lacerta from the Tigris-Euphrates basin and B. kubanicus from the Kuban basin. The genetic structure of Black Sea barbels was influenced by glaciation-deglaciation periods accompanied by freshwater phases, periods of migration and the colonization of Black Sea tributaries. Intra-and intergeneric hybridization among Caucasian barbines was revealed for the first time. In the present study, we report the discovery of B. escherichii in the Kuban basin, where only B. kubanicus was known to inhabit.Hybrids of these two species were detected based on both mtDNA and nDNA markers. Remarkably, the Kuban population of B. escherichii is distant to closely located conspecific populations, and we consider it as a relic. We reveal the intergeneric hybridization between evolutionary tetraploid (2n=100) B. goktschaicus and evolutionary hexaploid (2n=150) Capoeta sevangi in Lake Sevan.

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Summary In experiment with hormonal manipulation of developmental rate (alteration of thyroid status) of two cyprinid species, Abramis brama and Rutilus rutilus, we found that number of scales strongly correlates with body size at the moment of first scale appearance. If squamation development starts earlier and at a shorter body length, it results in reduction of scale numbers. If squamation development starts later and at a larger body length, the number of scales is increased. Calculated distances between scales at the moment of their appearance are the same in the different experimental groups despite of acceleration or retardation of developmental rate and a corresponding change in the number of scales (decreasing and increasing). It suggests that size of body at the moment of scale initiation determines the number of scales. Induced heterochrony in initiation of squamation is one of the mechanisms, which is evidently responsible for intraspecies variability in scale numbers and might be considered a relevant reason for differences between close‐related species in case of evolutionary fixed heterochronies of scale initiation. Another plausible path for diversity in scale number is a change in distance between forming scales that seems to be more appropriate for species represented phylogenetically more distant lineages.

Alburnoides holciki was described from the Hari River basin, which was the only basin it was known from. Populations from the Amu Darya basin were previously recognized as A. eichwaldii or Alburnoides sp. Our study recognized specimens of Alburnoides from the Amu Darya basin as A. holciki based on morphological data and the COI barcode gene. The population from the Zeravshan basin showed some morphological differences compared to others but were similar in the COI gene and needs further investigation. New results extend the range of A. holciki for almost 1000 km ­from the Hari River to the upper Amu Darya tributaries in Tajikistan. The intraspecific genetic similarity in the COI gene between populations in the Hari and Amu Darya rivers supports the geographical hypothesis of a recent connection of these rivers.