Paulo Roberto Antunes de Mello Affonso

Populations of the Neotropical deer of the genera Mazama and Subulo are susceptible to hunting and habitat losses and usually present distinct cytotypes that may compromise captive conservation programs. The aim of this study was to cytogenetically characterize specimens identified as grey brocket deer (Subulo gouazoubira ) kept in a Zoological Park in Northeastern Brazil to assess the genetic profile of the captive stock and identify potential risks of hybridization. The analysis revealed marked chromosomal differences among individuals, including one specimen with 2n=38 and submetacentric X chromosomes consistent with M. jucunda , whereas the remaining animals exhibited the S. gouazoubira pattern, with 2n ranging from 64 to 70. Variable numbers of B chromosomes were also observed among specimens, as well as an apparent case of monosomy. Fluorochrome staining revealed structural divergences between M. jucunda and S. gouazoubira , in addition to GC-rich region polymorphisms in S. gouazoubira . The results indicate the simultaneous presence of distinct species and multiple cytotypes within the stock, representing a real risk of hybridization and reduced progeny viability. We conclude that strict reproductive control and expanded cytogenetic monitoring are required to ensure the appropriate management of neotropical cervids in captivity.

The small characins represent a systematic puzzle in the Neotropical ichthyofauna as a result of independent miniaturization processes, adaptive convergence and lack of diagnostic characters for several genera. In order to diminish the taxonomic uncertainties and the evolutionary pathways in Hemigrammus , we carried out an integrative genetic analysis in the putatively widespread Hemigrammus marginatus Ellis, 1958 by combining cytogenetic and molecular data based on the mitochondrial Cytochrome C Oxidase subunit I (COI). Specimens of H. marginatus from the type locality in Itapicuru River basin and other two populations from coastal rivers in northeastern Brazil were analyzed and compared with the available data from other regions in South America. Conspicuous macro and microkaryotypic differences were detected between the samples from northeastern and southern Brazil (Upper Paraná River basin). Likewise, the DNA barcoding and species delimitation analyses recovered distinct Molecular Operational Taxonomical Units within H. marginatus . Therefore, the population from the type locality should be referred to as H. marginatus stricto sensu , representing a restricted characin taxon from coastal drainages (including the São Francisco River basin) along northeastern Brazil, while other populations of this small characin fish need to be taxonomically revised and managed as unique lineages.

Sea-level changes during the Pleistocene and the geomorphological history have largely molded the intricate shaping of coastal drainages in Eastern South America. Therefore, freshwater fishes from this region are promising models to infer how riverine isolation and reconnections affected their genetic diversification and geographic distribution. In the present study, we provided a detailed cytogenomic analysis of Ancistrus multispinis and Ancistrus brevipinnis, including the physical mapping of repetitive DNA classes, to verify whether chromosome differentiation would be related to the split between two major watersheds in Southern Brazil. Both species of Ancistrus shared the same modal diploid number (2n=52) and karyotype formulae (14 metacentric, 8 submetacentric and 30 subtelo/acrocentric chromosomes), besides single and terminal 18S ribosomal cistrons, (CGG)10 microsatellite sequences interspersed with heterochromatin in nucleolar organizer regions and a dispersed content of (AC)15 and (GT)15 microsatellites. In turn, the patterns of heterochromatin distribution, number of (GAG)10 microsatellites and 5S rDNA clusters diverged between both taxa. Most likely, these microstructural differences were determined by independent evolutionary processes, strongly associated to the geographic isolation between watersheds. Furthermore, the mapping of repetitive DNAs revealed a dynamic reorganization of genomes of Ancistrus, being useful for the taxonomic disambiguation in this complex group of Neotropical fish.

Once fishes and rivers are intrinsically connected, historical events such as river captures and the reconfiguration of palaeodrainages affect population structure and species distribution. However, direct evidence of these events remains limited. We aimed to directly infer putative connections between adjacent river basins to understand genetic and geographical patterns in populations and species of the ‘Geophagus’ brasiliensis complex. For that, we analysed 174 sequences of the mitochondrial gene cytochrome c oxidase subunit I (COI) from five species along 35 sites within and near a coastal basin in northeastern Brazil. Based on haplotype network, palaeodrainage reconstruction, geological inferences of river captures and analyses of molecular variance (AMOVAs), we tested how the genetic structure could be associated with variable patterns of habitat connectivity through time. In general, high levels of genetic variation were identified, including shared haplotypes among drainages for most species. AMOVA suggested that drainage rearrangements between adjacent basins were the main drivers of genetic diversification in the ‘G.’ brasiliensis complex. Our study refuted dispersal routes via the continental shelf, whereas eight putative river captures suggested historical connections that enabled gene flow among drainages until recent interruption. These results provide novel insights on the role of riverscape evolution on the biogeography of neotropical ichthyofauna.

The high dynamism of repetitive DNAs is a major driver of chromosome evolution. In particular, the accumulation of repetitive DNA sequences has been reported as part of the differentiation of sex-specific chromosomes. In turn, the fish species of the genus Megaleporinus are a monophyletic clade in which the presence of differentiated ZZ/ZW sex chromosomes represents a synapomorphic condition, thus serving as a suitable model to evaluate the dynamic evolution of repetitive DNA classes. Therefore, transposable elements (TEs) and in tandem repeats were isolated and located on chromosomes of Megaleporinus obtusidens and M. reinhardti to infer their role in chromosome differentiation with emphasis on sex chromosome systems. Despite the conserved karyotype features of both species, the location of repetitive sequences - Rex 1, Rex 3, (TTAGGG)_n, (GATA)_n, (GA)n, (CA)_n, and (A)_n - varied both intra and interspecifically, being mainly accumulated in Z and W chromosomes. The physical mapping of repetitive sequences confirmed the remarkable dynamics of repetitive DNA classes on sex chromosomes that might have promoted chromosome diversification and reproductive isolation in Megaleporinus species.

Chromosomal polymorphisms have been reported in numerous vertebrates, including fishes. Such variation is usually related to karyoevolutionary trends and speciation but might also be a result of environmental stress. Herein, we provide the first karyotype characterization in populations of a widespread small characin (Hemigrammus marginatus) from an impacted river basin in Northeastern Brazil to infer their chromosome organization and putative genotoxic effects. Therefore, we reported intra and interindividual structural polymorphism and multiple active nucleolar organizer regions in samples from Contas River, a highly polluted environment when compared to less impacted areas. Furthermore, this report represents the first description of chromosomal mosaicism in the family Characidae so far. Besides revealing peculiar karyotypic patterns in relation to populations from other basins, our results suggest that the chromosomal instability in specimens H. marginatus might be associated with the presence of xenobiotics in polluted environments.

The river basins of Brazil contain a highly diverse ichthyofauna of remarkable endemism, including several threatened species. Accordingly, Lignobrycon myersi is a fish species distributed only in a few rivers from the state of Bahia, northeastern Brazil. Since this species is classified as Near Threatened and is poorly studied, efforts to understand the genetic structure of populations and putative cryptic forms should help define efficient strategies of management and conservation. Herein, the molecular identification and the population genetic diversity of specimens of L. myersi across their range (Almada, Contas, and Cachoeira river basins) were assessed using mitochondrial markers (16S rDNA and D-Loop, respectively). The inferences based on phylogenetics, genetic distance, and species delimitation methods invariably identified all samples as L. myersi . In addition, sequencing of D-loop fragments revealed significant haplotype diversity and a considerable level of population genetic structure. Despite their geographic isolation, these data suggested that populations from Almada and Contas rivers represent a single evolutionary lineage that could be managed as a whole. In contrast, the population from Cachoeira River was highly differentiated from the others and should be managed separately as a unique and endemic unit, particularly focused on the conservation of native habitats.

Hypostomus Lacépède, 1803, is a species-rich and widespread fish genus from the Neotropical region, but its evolutionary history and systematics remain largely unclear. In addition, species from regions with high levels of species richness and endemism such as the Northeastern Mata Atlântica (NMA) and São Francisco (SF) hydrographic freshwater ecoregions are underrepresented in phylogenetic studies so far. In this study, we performed a broad sampling of Hypostomus in NMA and SF to investigate the interspecific boundaries and phylogenetic relationships using a multilocus approach based on one mitochondrial and three nuclear markers. Seven genetic groups were found for both ecoregions, in addition to one lineage exclusive to the SF represented by populations of the species Hypostomus velhochico. Moreover, multilocus analyses validated 16 formally described species and two new lineages for the NMA and SF ecoregions, as well as putative cases of species complexes. In general, lineages with independent evolutionary histories were revealed within the same ecoregion alongside genetically related groups between NMA, SF, and other ecoregions. These data reinforce the intricate scenario of this group of Neotropical fish and are useful to outline further phylogeographic studies in Hypostomus.

Bees represent efficient bioindicators of environmental contamination, including elements that can accumulate in both biomes and bee-derived products. Therefore, the goal of this study was to evaluate the presence of metallic elements over the body surface of Melipona quadrifasciata anthidioides workers from rural and urban areas from Caatinga in Brazil. Using SEM/XEDS (scanning electron microscope/energy dispersive X-ray spectroscopy) identified magnesium (Mg), aluminum (Al), calcium (Ca), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), molybdenum (Mo), cadmium (Cd), barium (Ba), and lead (Pb) in the corbiculae of bees. The areas had similar profiles, but As was characterized as a “trace element” in the agricultural area and “minor element” in the urban area. The presence of toxic elements such as As, Cd, and Pb indicates that both areas may be contaminated, revealing the importance of metallic elements microanalysis in native bee species for environmental biomonitoring.