Jorge Abdala Dergam

A biodiversity approach in the neotropical Erythrinidae fish, Hoplias malabaricus. Karyotypic survey, geographic distribution of cytotypes and cytotaxonomic considerations

Hoplias malabaricus, a widely distributed neotropical freshwater fish, shows a conspicuous karyotypic diversification. An overview of this diversity is presented here comprising several Brazilian populations, and some others from Argentina, Uruguay and Surinam. Seven general cytotypes are clearly identified on the basis of their diploid number (2n=39 to 2n=42), chromosomal morphology and sex chromosome systems, which can be clustered into two major karyotypic groups. This clustering suggests that karyotype structure would be more informative than the diploid number regarding cytotype relationships in this fish group. While some cytotypes show a wide geographical distribution, some others appear to be endemic to specific hydrographic basins. Sympatric cytotypes can occur without detection of hybrid forms; this situation points to a lack of gene flow, a fact that is also reinforced by studies with genomic markers. The karyotypic data support the view that the nominal taxon H. malabaricus corresponds to a species complex comprising distinct evolutionary units, each with well-established chromosomal differences.

Genetic variability of the Brazilian hair sheep breeds

The objectives of this work were to investigate the genetic structure of the Brazilian hair sheep breeds and to determine the origin of the Santa Ines breed. Molecular similarity was determined using Randomly Amplified Polymorphic DNA - Polymerase Chain Reaction markers in 238 individuals from five naturalized sheep breeds: Santa Ines (48 animals), Rabo Largo (48), Somali (48), Morada Nova (48) and Bergamasca (46), collected in Goias, Sergipe, Bahia, and Ceara States as well as in the Federal District. Fifty-four loci were selected from 19 primers, after a pilot test using 140 primers. Qualitative analyses indicate diagnostic markers for all breeds. All breeds were significantly different from each other. Interbreed differences were explained by 14.92% of the total variation. Santa Ines clustered with Bergamasca (97% bootstrap) and with Rabo Largo, composing the third member of the group (81% bootstrap) while Morada Nova and Somali breeds clustered separately. Each breed should be considered as a separate management and conservation unit, and special care should be taken with Rabo Largo, Morada Nova and Somali breeds, represented by small herds in Brazil.

Molecular biogeography of the Neotropical fish Hoplias malabaricus (Erythrinidae:Characiformes) in the Iguaçu, Tibagi, and Paraná Rivers

Hoplias malabaricus, the common trahira, extended its range into the Iguacu River sometime in the last decades. To determine levels of genetic differentiation in neighboring basins of this nominal taxon, as well as to unveil the source of the invading population, we analyzed patterns of similarity of RAPD-PCR genomic markers of samples from Parana, Iguacu and Tibagi Rivers. The high genetic diversity of samples from the Parana and Tibagi Rivers suggested strong population structuring or even the occurrence of undescribed species. All alleles of the sample from the headwaters of Tibagi River were present in the sample from the Iguacu River, which suggests that the former population or another population with similar genetic makeup, may be the source of the trahiras of the Iguacu River.

Molecular and karyotypic phylogeography in the Neotropical Hoplias malabaricus (Erythrinidae) fish in eastern Brazil

The sedentary, predatory characin Hoplias malabaricus has one of the widest distributions of freshwater fishes in South America and is characterized by seven karyomorphs (A-G) that occur in sympatric and allopatric populations. Karyotypical patterns of variation in wild populations have been interpreted as evidence of multiple lineages within this nominal species, a possibility that may limit the validity of experimental data for particular karyomorphs. This study used the phylogeographic and genealogical concordance between cytogenetic (N = 49) and molecular (mitochondrial DNA) (N = 73) data on 17 samples, collected in 12 basins from south-eastern and north-eastern Brazil, to assess the systematic value of cytogenetic data. Cytogenetic patterns show a sex chromosome system in the 2n = 40F karyomorph. Molecular and cytogenetic data indicate a long, independent evolutionary history of karyomorphs and a coastal origin of continental populations in south-eastern Brazil. The lack of fit with molecular clock expectations of divergence between groups is likely to be due to strong demographic fluctuations during the evolution of this species complex. The results indicate that karyotypical identification provides a reliable baseline for placing experimental studies on Hoplias spp. in a phylogenetic context.

Determining management units in southeastern Brazil: the case of Astyanax bimaculatus (Linnaeus, 1758) (Teleostei: Ostariophysi: Characidae)

Characterization, management and protection of biodiversity are the most prominent challenges in conservation biology. Analyses on molecular similarity (Random Amplified Polymorphic DNA-Polymerase Chain Reaction, RAPD-PCR) and morphologic patterns (morphometric and meristic characters) were performed to evaluate the existence of population structuring in the Doce river basin, in a widespread small-sized characin, Astyanax bimaculatus. Three hundred (300) individuals were collected from six locations isolated by waterfalls or dams, in the Doce river basin, Minas Gerais State, Brazil. Genetic differentiation among tributaries was significant (p<0.00001) and accounted for 21% of total variance (p<0.00001). Only the Grande waterfall of the Casca river was an effective factor for differentiation of populations (p<0.00001), and meristic characters were also consistent with molecular data. We concluded that genetic and morphologic variation of this species was not necessarily associated with waterfalls and that molecular and meristic data are effective predictors of population divergence in this basin. The consequences of these findings for the protection and management of aquatic biodiversity were discussed.

Plagioscion squamosissimus (Sciaenidae) and Parachromis managuensis (Cichlidae): A Threat to Native Fishes of the Doce River in Minas Gerais, Brazil

The middle section of the lake basin of the Doce River in Minas Gerais State, Brazil is plagued by grave environmental problems, including the introduction of non-native fish, which reduces the biodiversity of this region. This study reports the presence of two newly-detected non-native species in the Doce River Basin. Sampling efforts included gill nets with mesh size of 3 to 12 mm (measured diagonally) and trawling nets, both of which were used in independent field campaigns in 2002 and 2011. The two new invasive Perciform fishes, Plagioscion squamosissimus (Heckel 1840) and Parachromis managuensis (Günther 1867) were collected in Caratinga and Rio Doce municipalities. These records and other reports on non-native fishes suggest favorable environmental conditions for the establishment of invasive species in this drainage. These invasive species have behavior and diet observed in other wide distribution exotic fish of Rio Doce Basin representing a threat to the 77 native fishes of this region, 37 of which are endangered.

Pleistocene karyotypic divergence in Hoplias malabaricus (Bloch, 1794) (Teleostei: Erythrinidae) populations in southeastern Brazil

O sistema lacustre da bacia do medio rio Doce e considerado um paradigma da geomorfologia do Pleistoceno. Nestes lagos, dois cariomorfos de Hoplias malabaricus (2n = 42A e 2n = 42B) vivem em sintopia na lagoa Carioca. Analises citogeneticas foram realizadas em 65 amostras de 8 lagos (incluindo lagoa Carioca) para determinar a distribuicao e frequencia relativa destes cariomorfos e o grau de divergencia citogenetica aparentemente causada pelo isolamento geografico recente. Todos os peixes apresentaram o cariomorfo 2n = 42B, com excecao de 1 especime da lagoa Marola, que foi 2n = 42A. Entre as populacoes, a variacao foi especialmente elevada nos padroes de bandamento C. Outros caracteres como o tamanho do cromossomo X e os padroes de CMA3/DAPI tambem variaram entre as populacoes. Nossos resultados sugerem que o genoma de H. malabaricus e capaz de responder rapidamente ao isolamento geografico, revelando que a variacao de heterocromatina pode representar o nivel hierarquico mais baixo de evolucao cromossomica.

New Hyphessobrycon from the upper rio Pardo drainage in eastern Brazil (Teleostei: Characiformes: Characidae)

A new species of characid, Hyphessobrycon vinaceus, is described from the upper rio Pardo, Minas Gerais, Brazil. The new species is distinguished from all other Hyphessobrycon species by the combination of the following characters: the body red or reddish pigmented in live specimens, an anterior and conspicuous vertically elongate black humeral spot followed by a second faint humeral spot, 5 teeth in the inner series of premaxilla, maxilla with 2-3 pentacuspidate teeth, 15-17 branched analfin rays, 4-5 scale rows above and 3-4 scale rows below lateral line, lateral line with 10-26 perforated scales, 32-34 scales in a longitudinal series, and by a smaller head length in relation to standard length (23.9-26.7%). Uma nova especie de caracideo, Hyphessobrycon vinaceus e descrita para o alto rio Pardo, Minas Gerais, Brasil. A nova especie distingue-se das demais especies de Hyphessobrycon pela combinacao dos seguintes caracteres: coloracao avermelhada do corpo em vida, uma mancha umeral preta e conspicua verticalmente alongada seguida de uma segunda mancha umeral fracamente pigmentada, 5 dentes na serie interna do pre-maxilar, 2-3 dentes pentacuspidados no maxilar, 15-17 raios ramificados na nadadeira anal, 4-5 escamas acima e 3-4 escamas abaixo da linha lateral, 10-26 escamas perfuradas na linha lateral, 32-34 escamas em uma serie longitudinal e menor comprimento da cabeca em relacao ao comprimento padrao (23,9-26,7%).

Closely Related Syntopic Cytotypes of Astyanax taeniatus (Jenyns, 1842) from the Upper Piranga River, Upper Doce Basin in Southeastern Brazil

Astyanax taeniatus occurs in coastal areas of southeastern Brazil, and it is very abundant in the Upper Doce River Basin. Our objective was to study C-, argyrophilic nucleolar organizer region (Ag-NOR) and fluorescent in situ hybridization (FISH) banding patterns using 5S, 18S, CA(15), and GA(15) repetitive DNA probes on a population of A. taeniatus present in the Piranga River, in the Doce Basin. Two syntopic cytotypes were found, both with 2n = 50: cytotype A (14m + 12sm + 16st + 8t) and cytotype B (10m + 14sm + 18st + 8t). In both cytotypes, heterochromatic blocks occurred in all the chromosomes; Ag-NOR sites were multiple, ranging from four to eight. The 5S rDNA probe marked eight chromosomes in both cytotypes, a unique condition within Astyanax, suggesting a recent divergence between these cytotypes. The 18S rDNA probe differed between the cytotypes, marking 10 and 8 chromosomes in cytotypes A and B, respectively. CA(15) and GA(15) FISH patterns were mainly subtelomeric, but CA(15) showed centromeric markings that were diagnostic for each cytotype. Although overall cytogenetic evidence suggests that these cytotypes are closely related, morphological and molecular data in progress will provide further hypothesis test on their phylogenetic relationship.

Sequencing and comparative analysis of the Amblyomma sculptum mitogenome

The mitogenome of Amblyomma sculptum was sequenced, providing important information for understanding the evolutionary relationships among species of the A. cajennense complex. The mitochondrial genome has a circular structure with 37 genes, including 13 coding DNA sequences, two ribosomal RNA genes (12S rRNA and 16S rRNA) and 22 tRNA genes. Comparative analysis with the mitogenomes of six reference species of the genus Amblyomma revealed that the ND5 gene, which is related to energy metabolism, and control regions 1 and 2 of the mitogenomes have polymorphisms that can be exploited as molecular markers to differentiate A. sculptum from other tick species in the Amblyomma cajennense complex as well as other Amblyomma species.