Event Abstract Back to Event Adaptive radiation of labeobarbs (Labeobarbus; Cyprinidae) in the Genale River, East Africa: is this pure sympatric speciation? Boris A. Levin1*, Miriam Casal-López2*, Evgeniy Simonov1*, Yury Y. Dgebuadze3, Nikolai Mugue4, Alexei V. Tiunov3, Ignacio Doadrio2 and Alexander S. Golubtsov3 1 Institute of Biology of Inland Waters, Russian Academy of Sciences, Russia 2 National Museum of Natural Sciences (MNCN), Spain 3 Severtsov Institute of Ecology and Evolution (RAS), Russia 4 All-Russian Research Institute Fisheries and Oceanography, Russia Adaptive radiation is a key process in biodiversity maintenance and emergence of evolutionary novelties. Speciation without geographic isolation often is considered as the main evolutionary mechanism of adaptive radiations (Kondrashov & Mina 1986; Schliewen еt al. 1994; Seehausen & Wagner 2014). Such radiations seem to occur commonly in many lakes in various fish groups, while the same evolutionary processes under the riverine conditions are possible but less frequent (reviewed by Golubtsov, 2010). A presumptive riverine species flock composed of several sympatric Labeobarbus forms was discovered in the middle reaches of the Genale River, a part of Juba – Wabe Shebeli (JWS) basin in southeastern Ethiopia (Golubtsov 1993; Mina et al. 1998, Dimmick et al., 2001). Divergence of feeding-related morphology and preliminary gut content analysis pointed to the trophic specialization of these forms. The goals of our study were (1) to assess trophic resource partitioning using stable isotope analyses, and (2) to evaluate the genetic relationships among Genale barbs to test the hypothesis about a monophyly of the presumptive species flock (i.e. about the sympatric origin of the forms involved). DNA samples (n=159) and samples for stable isotope analyses (dried white muscles, n=116) were collected from the Genale R. Additional DNA samples (n=40) were collected from other parts of the large JWS river system. The isotopic composition of N and C was expressed in a δ-notation relative to the international standards (atmospheric nitrogen and VPDB, respectively). Measurement accuracy was ± 0.2 δ units. Two mtDNA markers, cytochrome b (1049 bp) and d-loop (615 bp), were analyzed. The phylogenetic tree was built using both BI and ML approaches with the use of available sequences from the Genbank for comparison. Bayes factor (BF) comparisons were used to test a monophyly of the JWS lineage. Haplotype network was constructed using the median joining algorithm. Genetic differentiation among populations was tested with the fixation index FST. Six Genale Labeobarbus forms are different in their mouth morphology including the generalized, lipped, two various scrapers, and large-mouthed phenotypes. One more form (found in 2009, later than others) do not display mouth specialization (exhibiting generalized or rarely lipped phenotypes) but differs from others in short and deep body. Stable isotope analysis revealed differences in δ15N values among most of these forms, indicating different foraging strategies (omnivorous, scraping, and piscivorous). Phylogenetic analysis of mtDNA markers confirmed the monophyly of JWS Labeobarbus lineage, suggesting an intra-basin radiation. Nevertheless, the Genale assemblage appears to have originated through a combination of allopatric and sympatric events. First, no genetic differences found between barbs exhibiting the generalized, lipped and high-bodied phenotypes. According to haplotype net of d-loop sequences, one of the scraping phenotypes (known as L. jubae – Levin et al., 2013) are closely related to the generalized Labeobarbus form from the Dawa drainage (the confluence of the Genale and Dawa makes an origin of the Juba, the Dawa drainage is adjacent to Genale one from the south). This scraping form was found beyond the range of the Genale flock within the Genale drainage and in the Dawa drainage in sympatry with local generalized form. Thus it originated apparently beyond the range of the Genale flock (most probably, in the Dawa drainage). Another scraping form was not found beyond the range of the Genale flock. It had unique haplotypes but very close to L. jubae, and most probably evolved in situ via sympatric divergence from the latter. The large-mouthed form was not found beyond the range of the Genale flock, but its haplotypes were similar to those of the generalized form from the Wabi Shebelle drainage, the northernmost in JWS basin. The large-mouthed predatory form might evolve either beyond or within the range of the Genale flock from the generalized form genetically distinct from the Genale generalist. Thus, we may suppose several independent divergence events and some of them occurred beyond the range of the Genale flock. Each of these divergence events should result in emergence of a mini-flock composed of two to three sympatric forms. Thus, the Genale Labeobarbus assemblage is likely a result of several events of sympatric ecological divergence that might occur in geographically distant localities, with subsequent dissipation via riverine net. As the Genale River is centrally located in a broad riverine net of the JWS basin, it could serve as a hub that facilitates migration from both southern (Dawa) and northern (Wabe Shebelle) drainages. Our study shows that adaptive radiation in rivers could be enhanced by a combination of sympatric speciation, temporal geographic isolation and hybridization. Acknowledgements The study was supported by Russian Science Foundation (grant no. 19-14-00218). We are grateful to all members of Joint Ethiopian-Russian Biological Expedition, who shared field operations, and especially to Dr. A.A. Darkov, the Expedition coordinator, for permanent and invaluable aid. Keywords: adaptive radiation, African fishes, resource partitioning, Sympatric speciation, molecular genetics Conference: XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019. Presentation Type: Oral Topic: TAXONOMY, PHYLOGENY AND ZOOGEOGRAPHY Citation: Levin BA, Casal-López M, Simonov E, Dgebuadze YY, Mugue N, Tiunov AV, Doadrio I and Golubtsov AS (2019). Adaptive radiation of labeobarbs (Labeobarbus; Cyprinidae) in the Genale River, East Africa: is this pure sympatric speciation?. Front. Mar. Sci. Conference Abstract: XVI European Congress of Ichthyology. doi: 10.3389/conf.fmars.2019.07.00100 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 May 2019; Published Online: 14 Aug 2019. * Correspondence: Dr. Boris A Levin, Institute of Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia, borislyovin@mail.ru Dr. Miriam Casal-López, National Museum of Natural Sciences (MNCN), Madrid, Madrid, 28006, Spain, miriam.casal.lopez@gmail.com Dr. Evgeniy Simonov, Institute of Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia, ev.simonov@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Boris A Levin Miriam Casal-López Evgeniy Simonov Yury Y Dgebuadze Nikolai Mugue Alexei V Tiunov Ignacio Doadrio Alexander S Golubtsov Google Boris A Levin Miriam Casal-López Evgeniy Simonov Yury Y Dgebuadze Nikolai Mugue Alexei V Tiunov Ignacio Doadrio Alexander S Golubtsov Google Scholar Boris A Levin Miriam Casal-López Evgeniy Simonov Yury Y Dgebuadze Nikolai Mugue Alexei V Tiunov Ignacio Doadrio Alexander S Golubtsov PubMed Boris A Levin Miriam Casal-López Evgeniy Simonov Yury Y Dgebuadze Nikolai Mugue Alexei V Tiunov Ignacio Doadrio Alexander S Golubtsov Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.