The Astyanax species of the bimaculatus group include morphologically similar representatives that share the same color pattern, corresponding to at least 20 species. Specimens from the São Francisco River basin and from the Grande River (Upper Paraná basin) are included in this group. In the early 1960’s, the Piumhi River, an original tributary of the Grande River, was transposed to the São Francisco River basin due to the construction of the Furnas Hydroelectric Power, in the state of Minas Gerais, Brazil. In this context, we characterized representatives of the bimaculatus group from both basins and from the transposition region of the Piumhi River, using chromosome characteristics obtained by conventional analyzes and fluorescence in situ hybridization with rDNA probes. All the analyzed specimens presented 2n = 50 chromosomes and similar localization of the nucleolus organizer regions (Ag-NORs), 18S rDNA and 5S rDNA sites. However, diagnostic chromosome differences were detected concerning the number of submetacentric and acrocentric chromosomes in the karyotypes, making possible the characterization of five distinct karyotypes (Cytotypes A–E), where the specimens from the São Francisco and from the Grande River correspond to Cytotypes A and B, respectively. In addition, these two Cytotypes were sympatrically found in the Piumhi River with specimens carrying a clear intermediate karyotype (Cytotype C), as well as with others harboring different karyotypes (Cytotypes D and E). Our data indicate that Cytotypes A and B probably diverged from each other during the prior geographic isolation. However, despite their chromosomal differentiations, they still maintain a close relationship which allows interbreeding and the formation of a secondary hybrid zone, due to the breakdown of the geographic isolation.
Reviews in Fish Biology and Fisheries – Springer Journals
Published: Nov 18, 2011
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera