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Chromosomal analysis of two Acanthodoras species (Doradidae: Siluriformes): Insights into the oldest thorny catfish clade and its karyotype evolution 
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  • Fabio Takagui,
  • Patrik Viana,
  • Chrystian Haerter,
  • Jansen Zuanon,
  • José Birindelli,
  • Roberto Lui,
  • Eliana Feldberg,
  • Vladimir Margarido
Fabio Takagui
Instituto Nacional de Pesquisas da Amazônia
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Patrik Viana
Instituto Nacional de Pesquisas da Amazônia
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Chrystian Haerter
Instituto Nacional de Pesquisas da Amazônia

Corresponding Author:[email protected]

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Jansen Zuanon
Instituto Nacional de Pesquisas da Amazonia
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José Birindelli
Universidade Estadual de Londrina
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Roberto Lui
Universidade Estadual do Oeste do Paraná
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Eliana Feldberg
Instituto Nacional de Pesquisas da Amazônia
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Vladimir Margarido
Universidade Estadual do Oeste do Paraná
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Abstract

The Doradidae fishes constitute one of the most diverse groups of Neotropical freshwater environments. Acanthodoradinae is the oldest lineage and the sister group to all other thorny catfishes, and it includes only the genus Acanthodoras. The diversity of Acanthodoras remains underestimated, and the use of complementary approaches, including genetic studies, is an important step to better characterize this diversity and the relationships among the species within the genus. Therefore, we conducted a comprehensive analysis using conventional cytogenetic techniques and physical mapping of three multigene families (18S and 5S ribosomal DNA [rDNA], U2 small nuclear DNA [snDNA]) and four microsatellite motifs, namely (AC)n, (AT)n, (GA)n, and (GATA)n, in two sympatric species from the Negro River: Acanthodoras cataphractus and Acanthodoras cf. polygrammus. We found significant differences in constitutive heterochromatin (CH) content, distribution of the microsatellite (AT)n, and the number of 5S rDNA and U2 snDNA sites. These differences may result from chromosome rearrangements and repetitive DNA dispersal mechanisms. Furthermore, the characterization of the diploid number (2n) of these Acanthodoras species enables us to propose 2n = 58 chromosomes as the plesiomorphic 2n state in Doradidae based on ancestral state reconstruction. Acanthodoradinae is the oldest lineage of the thorny catfishes, and knowledge about its cytogenetic patterns is crucial for disentangling the karyotype evolution of the whole group. Thus, this study contributes to the understanding of the mechanisms behind chromosome diversification of Doradidae and highlights the importance of Acanthodoradinae in the evolutionary history of thorny catfishes.
15 Jul 2024Published in Journal of Fish Biology. https://doi.org/10.1111/jfb.15863