Phylogeography of Drosophila buzzatii (Diptera, Drosophilidae): responses of the species to Quaternary climates in tropical and subtropical South America.

Drosophila buzzatii (Diptera: Drosophilidae) is a fly that breeds exclusively on decaying tissues of cacti species widely distributed in tropical and subtropical areas of South America. This distribution includes biomes in distinct climatic regimes (e.g., seasonal rain forest, semi-arid scrubs, savannas, and grasslands), which at first glance could might give the false impression that the species is not sensitive to either climate or vegetation physiognomies. However, detection of historical demographic events within D. buzzatii reveal the interplay between climate and the population structure of the species as the Late Quaternary climate changes occurred. To understand this process, we performed a phylogeographic analysis based on sequences of the mitochondrial gene COI for 128 individuals from 43 localities. Our analyses combined coalescent methods, population genetics, and paleodistributions estimation methods. Our study reveals that the COI haplotype diversity is geographically structured, with a decreasing cline from north to south. The results suggest an ancient range expansion, dated from 610k to 550k years before present, in the northernmost region of the species distribution, the Caatinga vegetation. More recently, an intense gene flow and a population expansion were detected in the central and south portions of its distribution. The demographic events detected date back to the glacial periods of the Quaternary.

Checklist of Omophoita Chevrolat, 1836 (Coleoptera: Chrysomelidae: Galerucinae: Alticini) and diagnoses for some species from southern Brazil: notes on the taxonomic history, redescriptions and new records.

Morphological descriptions, taxonomic history and distribution data of Omophoita species recorded for southern Brazil (states of Paran, Santa Catarina and Rio Grande do Sul) are presented. Through the analysis of the existing literature, databases, loaned material, and specimen collecting, we studied seven species of Omophoita recorded for southern Brazil: O. communis (Bechyn 1959), O. equestris (Fabricius 1787), O. magniguttis (Bechyn 1955), O. octoguttata (Fabricius 1775), O. personata (Illiger 1807), O. sesquilunata (Klug 1829), and O. sexnotata (Harold 1876). We report O. sesquilunata for this region for the first time. Updated morphological descriptions, including novel information for male and female genitalia are presented for those taxa with dissected specimens.

Molecular data reveal a complex population genetic structure for Psalidodon scabripinnis (Teleostei: Characidae) in the Atlantic Rainforest, Brazil.

Recently renamed, Psalidodon scabripinnis populations of Serra da Mantiqueira, previously known as Astyanax scabripinnis have been deeply studied in the last years. These populations are small and isolated and occur very close to the watershed between Paraíba do Sul River basin and Upper Paraná River basin, in Serra da Mantiqueira region in the Atlantic Rainforest. These conditions arouse the interest in knowing theor genetic conservation status and how they responded to the separation between the two rivers basins. Therefore, we accessed the genetic diversity of five P. scabripinnis populations of this region with microsatellites and mitochondrial data. The results showed a complex structure pattern that doesn't match the simple basin separation and a reasonably conservation status when compared with other populations of the same family or with similar natural history.

Genetic Diversity of the Cichlid Andinoacara latifrons (Steindachner, 1878) as a Conservation Strategy in Different Colombian Basins.

Cichlids constitute a diverse monophyletic group that have developed adaptive strategies to thrive in diverse environments. Andinoacara represents an example of diversification on the South American Andean uplift, providing a key model for understanding the evolution of biogeographic patterns. In this study, we analyzed the species Andinoacara latifrons using two mitochondrial markers (COI, cytb) and one nuclear marker (RAG1) in a populational level. Sequences were obtained through tissue collection and from the GenBank database. Populational analysis showed significant structuration among populations, also corroborated with population pairwise F st results. Fu's Fs and Tajima's D results showed populations that seems to be under populational expansion. We identified 22 haplotypes using cytb. The population associations in the Cauca haplotype are related to the Momposina depression and the mixture of the Cauca-Magdalena river basins in the lower Cauca-Magdalena region. We constructed a new phylogenetic tree, which grouped mainly two A. latifrons lineages: (1) an upper Magdalena and Catatumbo clade and (2) an upper Cauca and upper Magdalena clade. Thus, A. latifrons represents a diverse entity that contributes to our understanding of the evolutionary history of northern South America. Our findings provide insight into devising public policies in determining refuges for the preservation of biodiversity in the lower Cauca and Magdalena regions in Colombia.

Differential Expression of Genes Related to Sexual Determination Can Modify the Reproductive Cycle of Astyanax scabripinnis (Characiformes: Characidae) in B Chromosome Carrier Individuals.

The species complex Astyanax scabripinnis is one of the most studied with respect to origin, distribution, and frequency of B chromosomes, and is considered a model organism for evolutionary studies. Research using population inferences about the occurrence and frequency of the B chromosome shows seasonal variation between sexes, which is associated with the presence of this supernumerary element. We hypothesized that the B chromosome could influence the sex ratio of these animals. Based on this assumption, the present work aimed to investigate if differences exist among levels of gene expression with qRT-PCR of the amh (associated with testicular differentiation) and foxl2a (associated with ovarian differentiation) genes between B-carrier and non-B-carrier individuals. The results showed that for the amh gene, the difference in expression between animals with B chromosomes was not accentuated compared to that in animals without this chromosome. Expression of foxl2a in B-carrier females, however, was reduced by 73.56% compared to females that lacked the B chromosome. Males had no difference in expression of the amh and foxl2a genes between carriers and non-carriers of the B chromosome. Results indicate that the presence of B chromosomes is correlated with the differential expression of sex-associated genes. An analysis of these results integrated with data from other studies on the reproductive cycle in the same species reveals that this difference in expression may be expanding the reproductive cycle of the species.

Genetic variability in a population of Astyanax scabripinnis: recent bottleneck and the possible influence of individuals with B chromosomes

Access the genetic variability of endangered and isolated populations has become an important conservation tool. Astyanax scabripinnis is a well-known fish model for genetic studies, forming very isolated populations in headwaters. Besides that, this species frequently presents supernumerary chromosomes, which elevates the interest on genetic studies. Genetic diversity of an Astyanax scabripinnispopulation from the Atlantic Forest (Serra da Mantiqueira region, Brazil) was assessed with microsatellite markers for the first time. Since microsatellite markers are not described for this species, we tested markers described for a related species for transferability to A. scabripinnis. Six polymorphic loci were sufficiently reliable for population genetic analysis. We found that this population passed through a recent bottleneck because of the presence of an excess of heterozygotes, low allelic diversity, heterozygosity excess, and small effective population size. Individuals with and without B chromosomes were previously identified in this population and our study found private alleles in the individuals without B chromosomes. Furthermore, when individuals without B chromosomes were removed from the analysis, the population did not present heterozygosity excess, suggesting that the bottleneck event was driven by individuals with B chromosomes. Our results provide an insight into the value of microsatellite markers as molecular tools and is the first genetic study using molecular data of A. scabripinnis from this area.

Differential Expression of dmrt1 in Astyanax scabripinnis (Teleostei, Characidade) Is Correlated with B Chromosome Occurrence.

Astyanax is an abundant fish genus in South America. Some species of this group are characterized by the presence of B chromosomes and absence of morphologically differentiated sex chromosomes. In this study, we used quantitative real-time polymerase chain reaction to characterize mRNA expression of dmrt1 in Astyanax scabripinnis gonads. Maturing gonads of males with the B chromosome overexpressed dmrt1. Our findings suggest that B chromosomes may have an adaptive role in A. scabripinnis sex determination and maintenance.

From Chromosomes to Genome: Insights into the Evolutionary Relationships and Biogeography of Old World Knifefishes (Notopteridae; Osteoglossiformes).

In addition to its wide geographical distribution, osteoglossiform fishes represent one of the most ancient freshwater teleost lineages; making it an important group for systematic and evolutionary studies. These fishes had a Gondwanan origin and their past distribution may have contributed to the diversity present in this group. However, cytogenetic and genomic data are still scarce, making it difficult to track evolutionary trajectories within this order. In addition, their wide distribution, with groups endemic to different continents, hinders an integrative study that allows a globalized view of its evolutionary process. Here, we performed a detailed chromosomal analysis in Notopteridae fishes, using conventional and advanced molecular cytogenetic methods. Moreover, the genetic distances of examined species were assessed by genotyping using diversity arrays technology sequencing (DArTseq). These data provided a clear picture of the genetic diversity between African and Asian Notopteridae species, and were highly consistent with the chromosomal, geographical, and historical data, enlightening their evolutionary diversification. Here, we discuss the impact of continental drift and split of Pangea on their recent diversity, as well as the contribution to biogeographical models that explain their distribution, highlighting the role of the Indian subcontinent in the evolutionary process within the family.

Identification and chromosome mapping of repetitive elements in the Astyanax scabripinnis (Teleostei: Characidae) species complex.

Most part of the eukaryotic genome is composed of repeated sequences or multiple copies of DNA, which were considered as "junk DNA", and may be associated to the heterochromatin. In this study, three populations of Astyanax aff. scabripinnis from Brazilian rivers of Guaratinguetá and Pindamonhangaba (São Paulo) and a population from Maringá (Paraná) were analyzed concerning the localization of the nucleolar organizer regions (Ag-NORs), the As51 satellite DNA, the 18S ribosomal DNA (rDNA), and the 5S rDNA. Repeated sequences were also isolated and identified by the Cot - 1 method, which indicated similarity (90%) with the LINE UnaL2 retrotransposon. The fluorescence in situ hybridization (FISH) showed the retrotransposon dispersed and more concentrated markers in centromeric and telomeric chromosomal regions. These sequences were co-localized and interspaced with 18S and 5S rDNA and As51, confirmed by fiber-FISH essay. The B chromosome found in these populations pointed to a conspicuous hybridization with LINE probe, which is also co-located in As51 sequences. The NORs were active at unique sites of a homologous pair in the three populations. There were no evidences that transposable elements and repetitive DNA had influence in the transcriptional regulation of ribosomal genes in our analyses.

Population genetic study of mitochondrial DNA in Roseate spoonbill (Aves; Platalea ajaja) breeding colonies from the Pantanal wetlands, Brazil.

Five breeding colonies of the Roseate spoonbill (Aves: Platalea ajaja) from two Brazilian wetland areas (Pantanal and Taim marshes) were sampled, and domain I of the mitochondrial DNA control region (483 bp) was sequenced in 50 birds. The average haplotype diversity (h = 0.75, s = 0.071) and average nucleotide diversity (pi = 0.004, s = 0.003) were evaluated, and nonsignificant differences were found among the colonies studied. The lack of differentiation among breeding colonies revealed by AMOVA analysis was explained either as a consequence of high gene flow or recent expansion. The significantly negative results of the neutrality tests (Fu's F ( s ) = -23.271, P < 0.01; Tajima's D = -1.941, P < 0.01) associated with the star shape of the haplotype tree and mismatch distribution data are evidence supporting the idea that these populations underwent a recent demographic expansion in the Pantanal region. The average time since the expansion is estimated to be 25,773 years, and this agrees with a period of increased moisture that occurred during the last glacial period.