title: Delimiting Evolutionarily Significant Units of the Fish, Piaractus brachypomus (Characiformes: Serrasalmidae), from the Orinoco and Amazon River Basins with Insight on Routes of Historical Connectivity.
abstract: The freshwater fish Piaractus brachypomus is an economically important for human consumption both in commercial fisheries and aquaculture in all South American countries where it occurs. In recent years the species has decreased in abundance due to heavy fishing pressure. The species occurs in the Amazon and Orinoco basins, but lack of meristic differences between fishes from the 2 basins, and extensive migration associated with reproduction, have resulted in P. brachypomus being considered a single panmictic species. Analysis of 7 nuclear microsatellites, mitochondrial DNA sequences (D-loop and COI), and body shape variables demonstrated that each river basin is populated by a distinct evolutionarily significant unit (ESU); the 2 groups had an average COI divergence of 3.5% and differed in body depth and relative head length. Historical connection between the 2 basins most probably occurred via the Rupununi portal rather than via the Casiquiare canal. The 2 ESUs will require independent fishery management, and translocation of fisheries stocks between basins should be avoided to prevent loss of local adaptations or extinction associated with outbreeding depression. Introductions of fishes from the Orinoco basin into the Putumayo River basin, an Amazon basin drainage, and evidence of hybridization between the 2 ESUs have already been detected.
authors.affiliation: From the Laboratório de Evolução e Genética Animal, Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Av. Gen. Rodrigo Octávio Jordão Ramos, 3000, Campus Universitário, Bairro Coroado I, 69077-000 Manaus, AM, Brasil (Escobar, Farias, and Hrbek); Laboratorio Aplicado de Biogeografia y Bioacústica, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, DF, Colombia (Escobar); Laboratório de Sistemática de Peces, Instituto de Zoología Tropical, Universidad Central de Venezuela, Caracas, Venezuela (Andrade-López); and Facultad de Ciencias Agrarias. Fundación Universitaria Juan de Castellanos, Boyacá, Colombia (Andrade-López).
authors.forename: Maria Doris
authors.initials: MD
authors.lastname: Escobar
authors.affiliation: From the Laboratório de Evolução e Genética Animal, Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Av. Gen. Rodrigo Octávio Jordão Ramos, 3000, Campus Universitário, Bairro Coroado I, 69077-000 Manaus, AM, Brasil (Escobar, Farias, and Hrbek); Laboratorio Aplicado de Biogeografia y Bioacústica, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, DF, Colombia (Escobar); Laboratório de Sistemática de Peces, Instituto de Zoología Tropical, Universidad Central de Venezuela, Caracas, Venezuela (Andrade-López); and Facultad de Ciencias Agrarias. Fundación Universitaria Juan de Castellanos, Boyacá, Colombia (Andrade-López).
authors.forename: Juana
authors.initials: J
authors.lastname: Andrade-López
authors.affiliation: From the Laboratório de Evolução e Genética Animal, Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Av. Gen. Rodrigo Octávio Jordão Ramos, 3000, Campus Universitário, Bairro Coroado I, 69077-000 Manaus, AM, Brasil (Escobar, Farias, and Hrbek); Laboratorio Aplicado de Biogeografia y Bioacústica, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, DF, Colombia (Escobar); Laboratório de Sistemática de Peces, Instituto de Zoología Tropical, Universidad Central de Venezuela, Caracas, Venezuela (Andrade-López); and Facultad de Ciencias Agrarias. Fundación Universitaria Juan de Castellanos, Boyacá, Colombia (Andrade-López).
authors.forename: Izeni P
authors.initials: IP
authors.lastname: Farias
authors.affiliation: From the Laboratório de Evolução e Genética Animal, Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Av. Gen. Rodrigo Octávio Jordão Ramos, 3000, Campus Universitário, Bairro Coroado I, 69077-000 Manaus, AM, Brasil (Escobar, Farias, and Hrbek); Laboratorio Aplicado de Biogeografia y Bioacústica, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, DF, Colombia (Escobar); Laboratório de Sistemática de Peces, Instituto de Zoología Tropical, Universidad Central de Venezuela, Caracas, Venezuela (Andrade-López); and Facultad de Ciencias Agrarias. Fundación Universitaria Juan de Castellanos, Boyacá, Colombia (Andrade-López). hrbek@evoamazon.net.
authors.forename: Tomas
authors.initials: T
authors.lastname: Hrbek
mesh_terms: D000818:Animals; D005075:Biological Evolution; D060125:Characiformes / Q000235:genetics*; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000235:genetics; D005398:Fisheries; D005828:Genetics, Population; D006239:Haplotypes; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D010802:Phylogeny; D045483:Rivers; D017422:Sequence Analysis, DNA; D013020:South America
chemical_list: D004272:DNA, Mitochondrial
keywords: Casiquiare canal; Putumayo River; Rupununi portal; geometric morphometrics; hybridization; microsatellites; mitochondrial DNA