Riverine Populations Research Articles

People's risk perception of glacial lake outburst flooding: a case of Tsho Rolpa Lake, Nepal

Previous research indicates that people's perception of risk from a particular hazard positively influences their adoption of effective mitigation strategies and responses. This research investigates the risk perceptions of people living downstream from Tsho Rolpa Glacial Lake of Nepal. Field surveys revealed that people living beneath the Tsho Rolpa glacial lake possess a low risk perception despite the probability of a glacial lake outburst at their location. Further investigation reveals that many individuals have made no adjustments in response to the potential disaster. The low risk perception on the part of the riverine population is chiefly attributed to the cry-wolf effect of the 1997 evacuation that followed an inaccurate prediction of a Tsho Rolpa outburst. Previous remediation structures were kept in place, but appear to have created a false sense of security among those at risk. This overconfidence in the rudimentary efforts employed thus far is illustrated by the fact that many residents have moved their infrastructure even closer to the river channel in recent years. Partial mitigation efforts have muted people's perceptions of the environmental risk and have therefore increased the vulnerability of the communities to a probable outburst flood.

River dynamics shape clonal diversity and genetic structure of an Amazonian understorey herb

Summary 1. Clonal herbs are an important feature of the understorey of Amazonian forests. However, little is known about the environmental drivers determining the population genetics of these herbs and about the spatial scale of gene flow. 2. With amplified fragment length polymorphism markers, we analysed the clonal diversity and genetic structure of a clonal Amazonian herb (Heliconia metallica) in south‐eastern Peru at two spatial scales. First, we sampled leaves in 24 patches differing in flooding frequency and canopy openness in 2 km2 of a floodplain forest, and second in 21 riverine populations from the Andean foothills to the Amazon lowlands along a 550‐km stretch of river. 3. At the small spatial scale in the floodplain forest, the clonal diversity of H. metallica was higher at flooded than at non‐flooded sites, but clonal diversity did not increase with canopy openness. 4. At the large spatial scale, clonal diversity was very low in riverine populations at up‐ and downriver sites, suggesting that seedling recruitment was higher at mid‐altitudes where the flooding intensity is intermediate. Genetic diversity of riverine populations monotonously increased downriver, indicating unidirectional gene flow mediated by hydrochory. 5. Genetic differentiation among riverine populations was very low (FST = 0.06) and followed an isolation‐by‐distance pattern, indicating a stepping‐stone type of gene flow by seeds. Despite the much smaller spatial scale, genetic differentiation among patches in the floodplain forest was higher (FST = 0.16), due to spatially restricted gene flow in the forest understorey. 6. Synthesis. The genetic structure of H. metallica is the result of seedling recruitment being largely limited to flooded sites and of hydrochoric seed dispersal between populations growing on riverbanks. We conclude that river dynamics are the major determinant of the genetic structure of Amazonian plants and that largely undisturbed river systems, such as the Amazon, provide a crucial vector for gene flow, even at large spatial scales.

Ecological transcriptomics of lake-type and riverine sockeye salmon (Oncorhynchus nerka)

BackgroundThere are a growing number of genomes sequenced with tentative functions assigned to a large proportion of the individual genes. Model organisms in laboratory settings form the basis for the assignment of gene function, and the ecological context of gene function is lacking. This work addresses this shortcoming by investigating expressed genes of sockeye salmon (Oncorhynchus nerka) muscle tissue. We compared morphology and gene expression in natural juvenile sockeye populations related to river and lake habitats. Based on previously documented divergent morphology, feeding strategy, and predation in association with these distinct environments, we expect that burst swimming is favored in riverine population and continuous swimming is favored in lake-type population. In turn we predict that morphology and expressed genes promote burst swimming in riverine sockeye and continuous swimming in lake-type sockeye.ResultsWe found the riverine sockeye population had deep, robust bodies and lake-type had shallow, streamlined bodies. Gene expression patterns were measured using a 16K microarray, discovering 141 genes with significant differential expression. Overall, the identity and function of these genes was consistent with our hypothesis. In addition, Gene Ontology (GO) enrichment analyses with a larger set of differentially expressed genes found the "biosynthesis" category enriched for the riverine population and the "metabolism" category enriched for the lake-type population.ConclusionsThis study provides a framework for understanding sockeye life history from a transcriptomic perspective and a starting point for more extensive, targeted studies determining the ecological context of genes.

Reproduction and genetic detection of veligers in changingDreissenapopulations in the Great Lakes

Dreissenid bivalves, Dreissena polymorpha (zebra mussel) and Dreissena bugensis (quagga mussel) are biofouling species that invaded the Great Lakes region of North America from source populations in Europe in the 1980s. Initially, D. polymorpha spread faster and farther; however, D. bugensis have recently displaced D. polymorpha in many areas of the Great Lakes and was the first to be found west of the Continental Divide. Early detection of dreissenids is important in anticipating and preventing potentially high economic impacts. To study population dynamics and to enhance detection methods, we assessed “spawnability” using a serotonin bioassay and developed a new, sensitive, multiplex PCR method to identify veligers and verify adult species. Contrasting riverine populations were identified in the Saginaw River (100% D. polymorpha) and the Detroit River at Belle Isle (100% D. bugensis in 2010), and mixed populations of mussels (10% to ∼50% D. polymorpha) were found in Saginaw Bay, Lake Huron. In 1994, when the Detroit River population at Belle Isle was virtually all D. polymorpha (Ram et al. 1996), spawning could not be induced by serotonin until late May, and peak spawnability did not occur until early June. In 2010, D. bugensis at the same site could be induced to spawn in the first week of April, and reached near maximal spawning intensity by mid-May. In 2010, Detroit River veligers were first observed in April and, by PCR species-specific detection, were 100% D. bugensis. Veligers changed to a mixed population of both species later in May and rose to a peak, mixed population in early June. These experiments demonstrate a quantitative, species-specific detection of dreissenid veligers, and lay the groundwork for determining the role of early reproduction and other mechanisms in mediating the displacement of one species by a closely related “cousin.”

Ontogeny of osmoregulatory patterns in the South American shrimp Macrobrachium amazonicum: Loss of hypo-regulation in a land-locked population indicates phylogenetic separation from estuarine ancestors

Ontogenetic changes in osmoregulation were compared between two geographically separate populations of a South American shrimp, Macrobrachium amazonicum, originating from the Amazon delta (A) and the Pantanal (P), respectively. Population A lives in coastal rivers and estuaries in northern Brazil, whereas population P may be considered as land-locked, spending its entire life cycle in inland freshwater (FW) habitats in southwestern Brazil. All life-history stages of population A tolerated brackish and seawater (SW) conditions, being hyper-osmoregulators at salinities <17, iso-osmotic at ca. 17, and hypo-regulators at higher concentrations. The capabilities to survive and osmoregulate in FW were in this population expressed already at hatching (zoea I), but not any longer in the subsequent larval stages (II–IX), which showed complete mortality during an experimental 24h exposure to fully limnic conditions. FW tolerance re-appeared only in the juvenile and adult life-history stages. Similarly, the ability to hyper-regulate at salinities 1–5 was strong in the zoea I, weaker in the subsequent larval stages, and increasing again after metamorphosis. The function of hypo-regulation in concentrated media including SW was present throughout ontogeny, particularly in late larval and early juvenile stages. These ontogenetic patterns of osmoregulation and FW tolerance are congruent with a diadromous life cycle, which includes larval release in FW and a subsequent downstream transport of the salt-dependent early larvae towards estuarine or coastal marine waters, where development to metamorphosis is possible. The FW-tolerant juveniles can later migrate upstream, recruiting to riverine populations. In the land-locked population P, all life-history stages tolerated FW and brackish conditions up to salinity 25, but mortality was high in SW (100% in adults). All postembryonic stages of this population were hyper-osmoregulators at salinities <17, with a strong osmoregulatory capacity in FW. Unlike in population A, all stages were osmoconformers at higher salinities, lacking the function of hypo-regulation. In summary, our results show in two hydrologically and genetically isolated shrimp populations close relationships between differential patterns of ontogenetic change in osmoregulatory functions, salinity tolerance, and the ecology of successive life-history stages. In all postembryonic stages of the hololimnetic Pantanal population, the acquisition of an increased ability to hyper-osmoregulate in FW and, in particular, the complete loss of the ability to hypo-osmoregulate at high salt concentrations represent striking differences to the diadromous population from the Amazon estuary. These differences reflect different life styles and reproductive strategies, suggesting an at least incipient phylogenetic separation.

Fish diet from Manacapuru Big Lake complex (Amazon): a approach starting from the traditional knowledge

In the Amazon fishing is one of the main economic activities and higher value to traditional riverine communities of the region. Considering this importance is to suppose that the riverine populations have knowledge about fish fauna explores for them, because their forming culture that maintain a strait relationship with natural resources. This study aim to elevate the traditional knowledge of the fishermen from the riverine communities in the Big Lake Complex about the fish alimentary diet caught for commercialization and consumption. This study was realized in the Manacapuru Big Lake Complex through interview jointed with 62 fishermen. The results presents a detailed knowledge about the tambaqui, tucunaré, pacu, acará-açú, curimatã, aruanã, matrinxã, piranha and pirapitinga fish feeding compatible with the laboratory analyzes and with the specifics literature. Finally the traditional ecological knowledge from the fishermen about the fish ecology in the Big Lake must be used as a subsidy study of lakes management, establishing in this way, an information resource for scientific works at the same time to minimize the cost with a long research.

Sequential hair mercury in mothers and children from a traditional riverine population of the Rio Tapajós, Amazonia: Seasonal changes

Riverine populations of the Brazilian Amazon depend on fish for their principal source of protein, which changes in availability with seasonal fluctuations in the aquatic ecosystem. We report seasonal (high and low waters) and interannual changes in total mercury and methylmercury concentrations in hair of subsistence fish-eaters from a traditional riverine village on the banks of the Rio Tapajós in the Brazilian Amazonia. Retrospective exposure assessment was conducted from hair concentrations in segments representative of 2 years. A total of 32 mothers and their 51 children were studied. They reported high fish consumption (4–14 times a week). Ranges of total mercury and methylmercury concentrations in hair were 1.0–51.0 and 0.5–41.4 μg g −1, with means of 12.4 and 10.2 μg g −1, respectively. The relative mean value for methylmercury was 80%. There was a significant correlation between mothers and children for both total-Hg ( r=0.4826; P=0.003) and methyl-Hg ( r=0.5214; P=0.004). Mercury concentrations along hair strands of individuals showed significant variation coinciding with seasonal high and low waters. The changes in the aquatic environment impacted fish species availability, which is reflected in the total and MeHg concentrations in hair.

Contemporary and historical patterns of connectivity among populations of an inland river fish species inferred from genetics and otolith chemistry

Patterns of dispersal in riverine populations of Australian smelt ( Retropinna semoni ) were examined using otolith chemistry (Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca) and genetic markers (allozymes, mtDNA, microsatellite DNA). During a period of prolonged low flows, young-of-year smelt were collected from 13 streams within three catchments of the southern Murray–Darling Basin, Australia. Spatial differences in otolith core and edge chemical signatures and high levels of genetic assignment to sampling locations were observed, suggesting that most recruits were retained in natal areas after spawning. Following a subsequent period of hydrological connection, the same cohort was sampled as 1-year-olds. Maximum likelihood estimation using otolith core chemistry data from these fish suggested that retention in natal areas was highly variable between years and a similar, though less pronounced, pattern was evident in genetic assignments. Partitioning of genetic variation among catchments was not significant (FCT &lt; 0.004) and probably reflects disequilibrium between migration and genetic drift due to an historical population expansion (~270 000 years ago). Taken together, otolith chemistry and genetic analyses suggest that contemporary dispersal of smelt within these catchments is relatively restricted and may be mediated by changes in hydrological connectivity.

Sequence Polymorphism and Geographical Variation at a Positively Selected MHC-DRB Gene in the Finless Porpoise (Neophocaena phocaenoides): Implication for Recent Differentiation of the Yangtze Finless Porpoise?

Sequence polymorphism at the MHC class II DRB locus was investigated in three finless porpoise (Neophocaena phocaenoides) populations in Chinese waters. Intragenic recombination and strong positive selection were the main forces in generating sequence diversity in the DRB gene. MHC sequence diversity changed significantly along the study period. Significant decrease in heterozygosity and lost alleles have been detected in the Yangtze River population and South China Sea population since 1990. Furthermore, there is a trend of increasing population differentiation over time. Especially, the genetic differentiation between the Yangtze River population and the Yellow Sea population was very low prior to 1990 (F (ST) = 0.036, P = 0.009), but became very significant after 1990 (F (ST) = 0.134, P < 0.001), suggesting a recent augmentation of genetic differentiation between both populations probably in a relatively short-term period. Porpoises from the Yangtze River displayed divergent frequencies of shared and private alleles from those displayed by two marine populations, which suggest that the former riverine population has been under a different selection regime (characteristic of a fresh water environment) than that of its marine counterparts.

Psychometric properties of the OHIP-14 and prevalence and severity of oral health impacts in a rural riverine population in Amazonas State, Brazil

The objectives of this study were: (1) test the psychometric properties of OHIP-14 in a rural population; and (2) compare the oral health impacts in two riverine communities in the Brazilian Amazon that were living at different distances from an urban center. Data were obtained from a cross-sectional study in a consecutive sample (n = 126). The validity was assessed through the association of OHIP with clinical and subjective variables, which showed a more significant association with: pain, caries, need of extraction or endodontic treatment; than with tooth loss, periodontal disease or need of prostheses. The stability and internal consistency were good (ICC = 0.97; Cronbach's alpha = 0.89). The prevalence of oral impacts was greater in the community far from the urban center [70.3 (59.9-80.7)] than in the community closer to it [44.3 (30.7-57.7)], and in women [66.7 (56.0-77.3)] in comparison with men [49.1 (35.3-62.7)]. The OHIP-14 adapted to rural populations in Amazonas State was valid, reproducible, and consistent. There was high prevalence of impacts, especially for riverine communities that lived far from urban centers.

Seasonal movement patterns of Credit River brown trout (Salmo trutta)

Zimmer M, Schreer JF, Power M. Seasonal movement patterns of Credit River brown trout (Salmo trutta). Ecology of Freshwater Fish 2010: 19: 290–299. © 2010 John Wiley &amp; Sons A/SAbstract – Movement habits in riverine populations of brown trout vary among watersheds. Thus it is important to identify factors influencing differences in individual behaviour so as to improve the information resource base available for the design of river‐specific management strategies. Such information is particularly needed in the rapidly urbanising watersheds of eastern North America where relatively little is known about anthropogenic influences on brown trout populations. In this study, we examined the influence of water temperature on brown trout behaviour in the Credit River in south‐central Ontario, Canada with respect to seasonal movement patterns. Observed patterns of movement were also correlated with variations in river discharge and habitat quality. Forty‐three radio‐tagged, adult brown trout were tracked in a confined 39.8 km portion of the Credit River from 15 May 2002 to 28 July 2003. Fish were captured in three sections of the river that differed in distance downstream and habitat quality. Fish size had little impact on movement patterns. However, there was considerable variation in seasonal movement with upstream movements to summer positions, maintenance of summer positions, downstream and often extensive movements in fall. Also observed was maintenance of winter positions and repeated upstream movements in late spring‐early summer to previously used summer positions. The elaborate movement behaviour in the Credit River population was attributed to seasonal changes in thermal habitat quality. Fish tagged in less suitable thermal habitats moved significantly more than fish from more suitable thermal habitats.

Hazard, Vulnerability and Risk on the Brahmaputra Basin: A Case Study of River Bank Erosion

The authors present an assessment of risk from river bank erosion in the Brahmaputra river basin. The concept of risk is conceptualised in the context of socio-economic vulnerability, and the potential for exposure to hazard. By addressing both the physical hazard and the variations across the socio-economic surface the approach presented attempts to spatially combine these parameters to provide a risk surface for use by policy makers and decision makers at a number of administrative levels. The concept of vulnerability and risk as a description of the status of a society with respect to an imposed hazard such as flooding or the associated bank erosion exacerbated by climate change is deep rooted in a very broad research effort and its associated publications. In part, this reflects the complex evolution of the underlying notion of hazard - which itself shows the concurrent evolution of a series of strands each representing one disciplinary tradition. The concept of vulnerability has been very widely treated in the literature, and For present purposes an acceptable approach to vulnerability may be to start with an influential (but still controversial) established model by IPCC (2001) who have developed working definition - and then explore its ramifications in order to develop a set of working definitions and operational indicators for the project. This provides a pragmatic route towards a realistic target. It also offers a possible buffer against the common experience that the more sophisticated indices of vulnerability are strongly sensitive to contingent local/historical circumstances. This approach is explored within this chapter. The hazard posed by unabated bank erosion has been analysed with the help of satellite imagery based data and through adoption of Plan Form Index along with its threshold values develop for the Brahmaputra. The land loss to erosion is depicting a significantly rising trend which has obviously contributed to the impoverishment of the riverine population. The attendant uncertainties of climate change of hydrological and hydraulic river behaviour may exacerbate the channel instability of the Brahmaputra.

Worldwide status of burbot and conservation measures

AbstractAlthough burbot (Lota lota Gadidae) are widespread and abundant throughout much of their natural range, there are many populations that have been extirpated, endangered or are in serious decline. Due in part to the species’ lack of popularity as a game and commercial fish, few regions consider burbot in management plans. We review the worldwide population status of burbot and synthesize reasons why some burbot populations are endangered or declining, some burbot populations have recovered and some burbot populations do not recover despite management measures. Burbot have been extirpated in much of Western Europe and the United Kingdom and are threatened or endangered in much of North America and Eurasia. Pollution and habitat change, particularly the effects of dams, appear to be the main causes for declines in riverine burbot populations. Pollution and the adverse effects of invasive species appear to be the main reasons for declines in lacustrine populations. Warmer water temperatures, due either to discharge from dams or climate change, have been noted in declining burbot populations at the southern extent of their range. Currently, fishing pressure does not appear to be limiting burbot populations world‐wide. We suggest mitigation measures for burbot population recovery, particularly those impacted by dams and invasive species.

Life‐history variability of non‐native centrarchids in regulated river systems of the lower River Guadiana drainage (south‐west Iberian Peninsula)

Life-history variability of two non-native centrarchids, pumpkinseed Lepomis gibbosus and largemouth bass Micropterus salmoides, was evaluated in three stream stretches of the lower River Guadiana drainage (south-west Iberian Peninsula) with different degrees of regulated flows. Abundance, condition and population structure differed among populations for both species, but invasion success was lower in the least regulated river. Lepomis gibbosus were abundant and had multiple age classes in the three river sites, whereas M. salmoides were less abundant and mainly represented by young-of-the-year fish. Juvenile growth in L. gibbosus was similar in all three populations, though longevity was slightly greater in the population from the River Guadiana mainstream. Lepomis gibbosus exhibited a long reproductive season, but the duration of season, size at maturity and reproductive effort varied among populations. The life-history differences found demonstrate the importance of species adaptation to local conditions which might favour their invasion success. Lepomis gibbosus were more adaptable and resilient to local conditions, whereas M. salmoides seemed dependent on reservoirs and large rivers for maintenance of riverine populations.

Mitochondrial DNA diversity and relationships of endemic charrs of the genus Salvelinus from Lake Kronotskoye (Kamchatka Peninsula)

Lake Kronotskoye (the Kronotsky Biosphere State Reserve, south-eastern Kamchatka Peninsula) contains three closely related resident morphotypes charrs, which are considered to be either independent species (white charr Salvelinus albus, longhead charr Salvelinus kronocius, Schmidt’s charr Salvelinus schmidti) or a united lacustrine-riverine charrs, represented by several phenotypes. Salvelinus malma malma is isolated from the lake charr populations by an upstream migration barrier in the Kronotskaya River, which flows out of the lake. We examined the level of genetic variability and divergence of mtDNA both between charrs from Kronotsky Lake and between resident lacustrine charrs and the hypothetical ancestor species S. m. malma. The RFLP-PCR analysis was used to examine six regions (ND1/ND2, ND3/ND4L/ND4, ND5/ND6, COI/COII/A8, A8/A6/COIII/ND3, and Cytb/D-loop), comprising ~80% of the mtDNA. Significantly different levels of diversity were found among the populations of lacustrine charrs. S. albus and S. schmidti had the highest indices of mtDNA diversity among the investigated populations from the different habitats. Heterogeneity tests revealed highly significant differentiation among lake populations and among riverine (Kronotskaya River) and lake (Lake Kronotskoye) populations of charrs, indicating their reproductive isolation. Hierarchical analysis of molecular variance revealed the following regularities of diversity distribution: the high proportion of interpopulation variation (93.25%) and low but statistically significant subdivision between charr populations (6.75%, P < 0.001). Results of the present study suggest that the populations of S. albus, S. kronocius, S. schmidti belong to the S. m. malma phylogenetic group. The divergence value of mtDNA of resident charrs (0.0357–0.0010%) does not exceed the intraspecific variability of S. m. malma. The analysis of the mtDNA haplotypes genealogy of charrs showed that the low values of nucleotide divergence reflect a short period from the beginning of divergence from the ancestral lineages and are due to ancestral polymorphism, as well as to haplotype exchange between the diverged phylogenetic groups as a result of introgressive hybridization.

Survival strategies of human riverine populations in southern Brazil floodplain systems

Wetlands provide important resources to riverine populations. However, almost half of the world�s wetlands disappeared in the last century. The diminishment of these ecosystems compromises the sustainability of many regions of the planet, including South America. This study aims to identify survival strategies of riverine populations to withstand the hydrological disturbances during a hydrological cycle in a southern Brazil wetland. The study populations maintain the stability of their social structures by producing an identifi cation process through representations of fl oods and droughts. This knowledge is of relevance and can establish useful principles that can be used to ensure local sustainability of resources. The dependence of riverine populations on the natural resources, their management strategies, and sometimes their isolation, make these traditional populations important elements in conserving these natural systems. These aspects should be taken into account by decisionmakers, and should be included in development-oriented policies adopted for the region.

Survival strategies of human riverine populations in southern Brazil floodplain systems

Survival strategies of human riverine populations in southern Brazil floodplain systems

Predator–prey systems in streams and rivers

Many predator–prey systems are found in environments with a predominantly unidirectional flow such as streams and rivers. Alterations of natural flow regimes (e.g., due to human management or global warming) put biological populations at risk. The aim of this paper is to devise a simple method that links flow speeds (currents) with population retention (persistence) and wash-out (extinction). We consider systems of prey and specialist, as well as generalist, predators, for which we distinguish the following flow speed scenarios: (a) coexistence, (b) persistence of prey only or (c) predators only (provided they are generalists), and (d) extinction of both populations. The method is based on a reaction–advection–diffusion model and traveling wave speed approximations. We show that this approach matches well spread rates observed in numerical simulations. The results from this paper can provide a useful tool in the assessment of instream flow needs, estimating the flow speed necessary for preserving riverine populations.

Genetic Diversity and Population Structure in the Kuskokwim River Drainage Support the Recurrent Evolution Hypothesis for Sockeye Salmon Life Histories

AbstractRiverine sockeye salmon Oncorhynchus nerka (those that do not use nursery lakes for juvenile rearing) tend to be characterized by greater genetic diversity and weaker population structure than lake‐type populations. These findings have led to the “recurrent evolution” hypothesis for sockeye salmon life histories, which proposes that riverine sockeye salmon are the principal colonizing form and play the dominant role in the long‐term persistence of sockeye salmon in a dynamic landscape. However, previous studies in Kamchatka (Russia) and Alaska have suggested that the general patterns of riverine sockeye salmon do not apply in all parts of the species' range. In this study, we examined genetic diversity and population structure in lake‐type and riverine sockeye salmon from the Kwethluk and Holitna rivers (Kuskokwim drainage, western Alaska), near the northern edge of the species' range in North America. As expected, lake‐type sockeye salmon exhibited lower genetic diversity and stronger genetic structure over short distances than did neighboring riverine populations, which is consistent with increased straying of the riverine form. In the Kwethluk River, allele identity and genetic evidence of population bottlenecks in lake‐type samples suggested that lake‐type sockeye salmon were derived from riverine ancestors. These findings further support the recurrent evolution hypothesis and are consistent with the dynamic nature of the floodplain habitats that support these riverine sockeye salmon.

Preliminary insight into the age and origin of the Labeobarbus fish species flock from Lake Tana (Ethiopia) using the mtDNA cytochrome b gene

The high diversity of Cyprinid fish in Ethiopia’s Lake Tana appears to be an example of ecological differentiation and assortative mating leading to rapid sympatric speciation. Lake Tana’s Labeobarbus species flock consists of 15 morphological and ecological distinct species. This is the first attempt to determine the age and origin and inter-species relationships of Lake Tana’s Labeobarbus species using the mtDNA cytochrome b gene. Analysis of cytchrome b sequences shows that Lake Tana’s species flock appears to be young but the present dataset did not unequivocally support monophyly of Lake Tana’s species. Additional markers are needed to determine whether Lake Tana’s labeobarbs originated from a single or multiple incursion(s) of ancestral L. intermedius in the Lake Tana drainage basin, or the disruption of an ancient continuous riverine population by the emergence of the Tissisat waterfalls. Adaptive radiation and speciation within Lake Tana’s Labeobarbus species flock may have occurred in the last 10,000–25,000years, following the desiccation of Lake Tana around 17,000years ago, at the same time as Lake Victoria, however, obtaining more data using other (nuclear) markers is urgently required.