Genetic and biogeographical relationships among species of Astyanax (Teleostei, Characidae) in Brazilian river basins

Abstract

The genetic relationships among 17 species of Astyanax from the Iguaçu River and adjacent river basins in Brazil were examined using nucleotide sequences of the mitochondrial cytochrome b gene (cytb). Congruent trees were constructed using neighbor-joining, maximum-likelihood, and Bayesian methods. The resulting clades suggest that at least three major groups share similar origins with the endemic species of the Iguaçu River. The results indicate that Astyanax is polyphyletic in this location, which suggests that Astyanax did not diversify from a single ancestral group that was isolated when the Iguaçu River basin formed. Astyanax bifasciatus shares an origin with some species of the altiparanae-bimaculatus complex, while A. minor originated from the same group as A. aff. paranae, A. fasciatus, and A. bockmanni. The third group includes A. dissimilis, Astyanax sp F, and A. serratus that are endemic species to the Iguaçu River basin. Geological and hydrological events that influenced the biogeographical patterns of these species are discussed.

Trends in Karyotype Evolution in Astyanax (Teleostei, Characiformes, Characidae): Insights From Molecular Data

“…The phylogram obtained in the present work using the mitochondrial DNA sequence ( ATPase subunit 6) is mostly congruent with that obtained by Mello et al (2015) using the mitochondrial DNA sequence of the cytochrome b gene, as well as that obtained by Rossini et al (2016) using the mitochondrial COI sequence. Karyotypical data allow to give further support to at least some monophyletic groupings within the current genus Astyanax , corresponding to the major clades, as it was proposed by Travenzoli et al (2015) in Bryconidae.…”

“…Although little is known about the cause and effect of the rearrangements during the evolutionary process, the correlation between independent data sets such as molecular and chromosomal data suggest that some karyotypic signatures are associated with organismic evolution. Based on Cytochrome B (CytB) sequences, Mello et al (2015) found three genetically distinct clades out of 17 Astyanax nominal species from the Iguaçu and adjacent river basins. Likewise, using Cytochrome Oxydase I ( COI ) sequences, Rossini et al (2016) found five clades out of 64 nominal species plus 12 provisionally identified taxa.…”

Inventory of the ichthyofauna from the Jordão and Areia river basins (Iguaçu drainage, Brazil) reveals greater sharing of species than thought

“…Endemism in the two river basins inventoried here is high, and is thought to be associated with the formation of Iguaçu Falls in the Miocene (about 22 Mya), which isolated populations in the Iguaçu River (Mello et al 2015). Further explanations to the high rate of endemism in the Iguaçu basin have been developed lately.…”

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

“…Chromosomal data had long supported the idea that the genus Astyanax (Teleostei, Characiformes) was polyphyletic, as noted by Weitzman and Malabarba (1998 ), and had even revealed the existence of several cryptic species within the group, as summarized by Pasa and Kavalco (2007 ). More recently, molecular studies have provided further evidence for the formation of structured clades within Astyanax ( Mello et al, 2015 ; Rossini et al, 2016 ; Pazza et al, 2018 ; Pasa et al ., 2021 ), and it has become clear that chromosomal features are linked to these clades, especially with regard to the origin and spread of the As51 satellite DNA ( Mestriner et al, 2000 ) and the localization of the 5S ribosomal gene. Additionally, Pazza et al .…”