Cytotype-specific ISSR profiles and karyotypes in the Neotropical genus Eigenmannia (Teleostei: Gymnotiformes).
The genus Eigenmannia (Teleostei: Gymnotiformes), a widely distributed fish genus from the Neotropical region, presents very complex morphological patterns and many taxonomic problems. It is suggested that this genus harbors a species complex that is hard to differentiate using only morphological characteristics. As a result, many species of Eigenmannia may be currently gathered under a common name. With the objective of providing new tools for species characterization in this group, an analysis of the polymorphism of DNA inter-simple sequence repeats (ISSR), obtained by single primer amplification reaction (SPAR), combined with karyotype identification, was carried out in specimens sampled from populations of the Upper Paraná, São Francisco and Amazon river basins (Brazil). Specific ISSR patterns generated by primers (AAGC)(4) and (GGAC)(4) were found to characterize the ten cytotypes analyzed, even though the cytotypes 2n = 38 and 2n = 38 XX:XY, from the Upper Paraná basin, share some ISSR amplification patterns. The geographical distribution of all Eigenmannia specimens sampled was inferred, showing the cytotype 2n = 31/2n = 32 as the most frequent and largely distributed in the Upper Paraná basin. The cytotype 2n = 34 was reported for the first time in the genus Eigenmania, restricted to the São Francisco basin. Polymorphic ISSR patterns were also detected for each cytotype. Considering our results and the data reported previously in the literature, it is suggested that many of the forms of Eigenmannia herein analyzed might be regarded as different species. This work reinforces the importance of employing diverse approaches, such as molecular and cytogenetic characterization, to address taxonomic and evolutionary issues.
Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. cintilan@ib.usp.br
Cinthia Bachir
CB
Moysés
Maria de Fatima Zambelli
Mde F
Daniel-Silva
Carlos Eduardo
CE
Lopes
Lurdes Foresti
LF
de Almeida-Toledo
D000818:Animals; D005819:Genetic Markers / Q000235:genetics; D014644:Genetic Variation; D023702:Gymnotiformes / Q000145:classification / Q000235:genetics*; D007621:Karyotyping / Q000379:methods*; D011110:Polymorphism, Genetic; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D045483:Rivers; D014329:Tropical Climate
D005819:Genetic Markers