Biology subjects

Pasa, R.

Publications and source records attributed to Pasa, R..

3 recordsLinked to original sources

bioRxiv2020

Ten complete mitochondrial genomes of Gymnocharacini (Stethaprioninae, Characiformes): evolutionary relationships and a repetitive element in the Control Region (D-loop)

We are presenting the complete mitogenomes of eight fish species/cytotypes from Neotropical region belonging to the Astyanax and Psalidodon genus: A. aeneus, A. altiparanae, P. fasciatus (from two locations - Upper Parana and Sao Francisco river basins), A. lacustris, P. rivularis (two cytotypes) and P. rioparanaibano. We perform the whole-genome sequencing for six of these species in a Novaseq 6000 - by Illumina, meanwhile two genomes were assembled from raw data available in databases. Plus, we reassembled and annotated the mitochondrial genomes for A. mexicanus and P. paranae, both already described and with raw data available online. All the genomes presented the same organization, with 13 protein-coding genes, 22 tRNA genes and two rRNA genes. Aiming to contribute to the understanding of the several cryptic species complexes and phylogeny of the genus, we perform Bayesian analysis using the 13 protein-coding genes from these species, plus Deuterodon giton and using a Brycon species as outgroup.

genomics↗

bioRxiv2020

High congruence of karyotypic and molecular data on Hypostomus species from the Parana River basin

The Hypostomini tribe comprises a single genus, Hypostomus, which possibly contains several monophyletic groups because of significant morphological variation and a variety of diploid numbers and karyotype formulas. The objective of this study was to infer evolutionary relationships among some species of Hypostomus found in the Parana River basin and subsequently to identify chromosomal synapomorphies in the groupings formed. Two nuclear genes, rag1 and rag2, and two mitochondrial genes, mt-co1 and mt-cyb, were used to establish evolutionary relationships. Phylogenetic trees were inferred using the maximum likelihood (ML) method for mt-co1 and Bayesian analysis (BA) for all genes concatenated. Both phylogenetic trees showed two large monophyletic clades within Hypostomus. These clades are based on chromosome number, where haplogroup I contains individuals with 66-68 chromosomes, and haplogroup II contains species with 72-80 chromosomes. A third monophyletic haplogroup was also observed using ML, formed by H. faveolus and H. cochliodon, which present 2n = 64, reinforcing the separation of groups in Hypostomus by diploid number. Robertsonian rearrangements were responsible for forming the different diploid numbers and for the diversity of karyotype formulas. The groups based on traditional morphological taxonomy are considered artificial in this study; the staining pattern, which separates the two large groups morphologically and is supported by little chromosomal evidence, was instead determined to show homoplasy. Ag-NORs are predominantly multiple and located on st/a chromosomes, along with 18S rDNA sites; 5S rDNA sites are often seen in an interstitial position, following the trend already described for vertebrates.

evolutionary biology↗

bioRxiv2020

Chromosomal Radiation: a model to explain karyotypic diversity in cryptic species

Hypostominae is a subfamily of Loricariidae with great variation in color characters and external morphology. The genus Hypostomus presents the largest number of species ever karyotyped, with Hypostomus ancistroides characterized as a group of cryptic species. In the 15 natural populations of H. ancistroides studied, there are 15 different karyomorphs, with variations in diploid number, sex chromosome systems, and markers, such as C-banding and location of ribosomal cistrons. The objective of this work was to present molecular and chromosomal data of four new populations of Hypostomus ancistroides and to discuss the observed evolutionary trends for this group of a cryptic complex of species. We analyzed specimens from four sampling points in the Tiete, Mogi-Guacu, and Grande river basins, all in the state of Sao Paulo, southeastern Brazil. We performed techniques such as the detection of constitutive heterochromatin and ribosomal sites (5S and 18S), in addition to phylogenetic analyses. All specimens presented 2n=68 chromosomes without supernumerary elements or sex-related heteromorphisms. However, each population has a different karyotype with unique characteristics. The different karyomorphs are a consequence of the presence of Robertsonian rearrangements, such as centric fissions and pericentric inversions, which play an important role in the evolution of Hypostominae. Although variable in relation to the location of constitutive heterochromatin, we observed the presence of banding C in some chromosomes of all karyomorphs, which may indicate the existence of some homology. Another conservative feature is the presence of two pairs of subtelocentric or acrocentric chromosomes carrying 18S rDNA cistrons in the terminal region of the chromosomes. However, we observed the discontinuity of cytogenetic and phylogenetic data, with the formation of different groups (Araras + Indaiatuba and Botucatu + Terra Roxa in cytogenetics, in contrast to Araras + Terra Roxa and Botucatu and Indaiatuba in the phylogeny), suggesting that several derived karyomorphs may be produced from a pluripotent karyomorph as a result of the intrinsic plasticity of the species karyotype. Thus, each new arrangement would be independent in the forms analyzed, as they do not seem to be lineages from the same direct ancestor. Given the above, we believe that the genus Hypostomus continues to be one of the most diverse among the Siluriformes, however, we began to understand a little more about the karyotypic diversity of the group by associating different approaches, such as phylogenetic analyses.

evolutionary biology↗