Dhiego Gomes Ferreira

Genetic structure and diversity of migratory freshwater fish in a fragmented Neotropical river system

Over the past few decades, South American Rivers, including the Paraná River system, have been intensely impacted by dam constructions. To mitigate adverse impacts, fish passages were incorporated into two large dams on the Paraná River (Itaipu and Porto Primavera) to reestablish longitudinal connectivity, which is very important for conserving populations of migratory fish species. The aim of this study was to estimate genetic diversity, population differentiation and gene flow, using microsatellites markers and mitochondrial haplotypes (d-loop), in populations of Prochilodus lineatus, a long distance migratory species commonly found in Paraná River basin drainages. Samples were obtained from six locations in the Upper and Middle Paraná River: Porto Primavera Reservoir, downstream of the Porto Primavera Reservoir, four tributaries of this reservoir (Pardo, Peixe, Verde and Aguapeí Rivers) and in the Iguaçu River, downstream of the Itaipu dam. High genetic diversity was observed in all samples, as expected for species with large population sizes and high migration rates. However, the influence of other factors, such as secondary contacts, fish passages and restocking were also suggested. In general, evidence of spatial population structuring was not found, even though there were two large dams in the study area. This could also be attributed to the brief period that has elapsed since the dams were built, the influence of migratory and reproductive patterns and the possible contributory effects of the fish passages. Furthermore, the absence of population structuring also corroborates existing information that emphasizes the importance of unimpeded tributaries for conserving migratory fish populations in fragmented watersheds.

Development and characterization of 14 microsatellite loci in the Neotropical fish Geophagus brasiliensis (Perciformes, Cichlidae).

Fourteen polymorphic microsatellite loci were isolated and characterized for the Neotropical cichlid Geophagus brasiliensis and tested on 30 individuals belonging to a single population. Among the 14 loci described, four showed potential presence of null alleles, inferred from the excess of homozygous genotypes, and three of these loci showed significant deviations from Hardy-Weinberg equilibrium. Fifty-nine different alleles were detected (ranging from two to eight alleles per locus), with estimates of observed and expected heterozygosity ranging from 0·167 to 0·700 and from 0·269 to 0·825. Cross-amplification of primers was successful in five other cichlid species.

Cryptic species of the genus Pimelodella (Siluriformes: Heptapteridae) from the Miranda River, Paraguay River basin, Pantanal of Mato Grosso do Sul, Central Brazil

Exemplares de Pimelodella capturados no rio Miranda, Pantanal do Mato Grosso do Sul, apresentavam caracteristicas morfologicas que poderiam indicar, pelo menos, quatro especies. Entretanto, com a analise cariotipica e da biologia molecular ficou evidente que se tratava de apenas duas especies, uma apresentando 2n = 46 e a outra, 2n = 52 cromossomos, e com apenas 18% de similaridade genetica. Pela analise morfologica foi observado que o filamento dorsal e uma caracteristica de machos, e o lobo superior da nadadeira caudal se mostrou variavel, podendo, ou nao, ser alongado em ambas especies. Com relacao aos caracteres morfometricos, tambem houve a formacao de dois grupos, mas com uma pequena sobreposicao de exemplares entre eles. Das especies com filamento na nadadeira dorsal apontadas para o Pantanal, a que possui menor comprimento da base da nadadeira adiposa e P. griffini, o que corresponde aquela com 2n = 46 cromossomos e, ao contrario, a especie com 2n = 52 cromossomos, e P. taenioptera. Assim, apenas com o emprego de diversas tecnicas de analise foi possivel o reconhecimento seguro dessas unidades taxonomicas que se mostravam cripticas. Ressalta-se, ainda, que a identificacao de especies cripticas e importante para que estimativas da diversidade de peixes do Pantanal sejam feitas corretamente

Fishes (Osteichthyes: Actinopterygii) from the Penacho stream, upper Paraná River basin, Paraná state, Brazil

The focus of this work was to survey the ichthyofauna of the Penacho stream, a tributary of the Laranjinha River, northeastern Parana State, in an area of the Upper Parana River basin still devoid of ichthyofaunal studies. In general, the banks of the Penacho Stream are predominantly characterized by pasture or agricultural activities and may exhibit little riparian vegetation in few stretches. Fishes were collected at eight different locations, from its headwaters to its mouth, between February 2009 to March 2010. A total of seven orders, twelve families and thirty-three species, three of which not native to the basin, were reported. The fish species captured along the Penacho stream are those that still manage to stay in those environments, even in changed conditions. However, to better understand the effects of degradation on fish diversity, it is necessary to monitor it along time.

Genetic Diversity of the Endangered Neotropical Cichlid Fish (Gymnogeophagus setequedas) in Brazil

Gymnogeophagus setequedas is a rare and rheophilic species of tribe Geophagini, considered endangered in Brazilian red lists. Its previously known geographical distribution range was the Paraná River basin, in Paraguay, and a tributary of the Itaipu Reservoir in Brazil. Since its description no specimens have been collected in the original known distribution area. However, recent records of G. setequedas in the lower Iguaçu River, in a region considered highly endemic for the ichthyofauna, extended the known geographical distribution and may represent one of the last remnants of the species. The aim of this study was to estimate the genetic diversity and population structure of G. setequedas, using microsatellite markers and mitochondrial haplotypes, in order to test the hypothesis of low genetic diversity in this restricted population. Muscular tissue samples of 86 specimens were obtained from nine locations in the Lower Iguaçu River basin, between upstream of the Iguaçu Falls and downstream of the Salto Caxias Reservoir. Seven microsatellites loci were examined and a total of 120 different alleles were obtained. The number of alleles per locus (NA) was 17.429, effective alleles (NE) 6.644, expected heterozygosity (HE) 0.675, observed (HO) heterozygosity 0.592, and inbreeding coefficient (FIS) 0.128. Twelve haplotypes in the D-Loop region were revealed, with values of h (0.7642) and π (0.00729), suggesting a large and stable population with a long evolutionary history. Thus, both molecular markers revealed high levels of genetic diversity and indicated the occurrence of a single G. setequedas population distributed along a stretch of approximately 200 km. The pattern of mismatch distribution was multimodal, which is usually ascribed to populations in demographic equilibrium. Nevertheless, the construction of a new hydroelectric power plant, already underway between the Salto Caxias Reservoir and Iguaçu Falls, could fragment this population, causing loss of genetic diversity and population decline, and for this reason it is necessary to maintain the Iguaçu River tributaries and downstream area from the Lower Iguaçu Reservoir free of additional dams, to guarantee the survival of this species.

Isolation and characterization of 13 polymorphic microsatellite loci in Hypostomus ancistroides (Teleostei, Loricariidae) and cross-amplification in related species.

This study details 13 novel polymorphic microsatellite loci in the armoured catfish Hypostomus ancistroides, and assesses their utility for population genetic studies. The analysis of 30 individuals revealed a total of 99 different alleles (ranging from two to 15 alleles per locus), with an average of 7·62 alleles per locus, with observed and expected heterozygosities ranging from 0·103 to 0·931 and from 0·102 to 0·906, respectively. One of the 13 loci showed significant deviations from Hardy-Weinberg equilibrium, probably due to the presence of null alleles, inferred from the excess of homozygotes.

Development and characterization of fifteen polymorphic microsatellite loci in Bryconamericus aff. iheringii (Teleostei: Characidae) and cross-amplification in related Characidae species

Data on 15 novel microsatellite loci from the Neotropical fish Bryconamericus aff. iheringii are presented here. Analyses of 32 individuals from four different streams revealed 192 different alleles, ranging from four to 32 alleles per locus (mean of 12.8 per locus). Observed and expected heterozygosities ranged from 0.094 to 0.813 and 0.205 to 0.952, respectively. These loci showed high polymorphic information content and will be a resource for genetic studies of B. aff. iheringii. Furthermore, several loci also amplified other small Neotropical Characidae (Piabarchus stramineus and Piabina argentea) and should be useful for these species.

Structure and genetic variation among populations of Euschistus heros from different geographic regions in Brazil

The Neotropical brown stink bug, Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), is a major Brazilian soybean pest. Aiming to provide relevant information to implement pest and insecticide resistance management, new microsatellite loci were developed for E. heros and used in a study of genetic diversity and population structure. The population analysis was performed using eight microsatellite loci from 17 samples (n = 243 individuals) collected in the major soybean‐producing regions in Brazil (northeastern, midwestern, and southern regions). These microsatellite loci provided high genetic diversity values on the whole extension for the studied region (He = 0.895; total number of alleles = 400). Neotropical brown stink bug populations in general displayed low genetic structure levels among the samples (overall ΦST = 0.009). An exception was the sample from the northeastern region, which showed a significant genetic differentiation (pairwise ΦST = 0.031–0.063). Bayesian cluster analysis confirmed these results, did not show population subdivision, and indicated considerable levels of gene flow. Significant correlations between genetic differences and geographic distance were obtained. The lowest estimate of migration was found in the population from São Desidério, which was also the most distant from the remaining populations based on genetic distance. Some plausible hypotheses for the low genetic differentiation among these populations are the fast expansion of soybean production areas, the main food source of E. heros, polyvoltinism, and possible influence of anthropogenic dispersal. All these factors could have led to high population densities, a wide distribution that may contribute to reduced population differentiation, and increased genetic diversity.

Development and characterization of microsatellite loci of Microglanis cottoides (Siluriformes: Pseudopimelodidae) and cross-species amplification

Eigenmann 1912, also known as bumblebeecatfishes (Shibatta, 2003a), is a genus of small South Americancatfishes that do not exceed over 110 mm in standard length(Shibatta, 2003a; Shibatta & Benine, 2005). Initially regardedas a member of the pimelodids (Eigenmann, 1912), this genuswas subsequently included in the small Pseudopimelodidaefamily (Shibatta, 2003b), which is considered a monophyleticgroup (Lundberg