Centric Fusions behind the Karyotype Evolution of Neotropical Nannostomus Pencilfishes (Characiforme, Lebiasinidae): First Insights from a Molecular Cytogenetic Perspective

Author(s):Show less -

Sember, Alexandr ^[1] ; de Oliveira, Ezequiel Aguiar ^{[2, 3]} ; Rab, Petr ^[1] ; Bertollo, Luiz Antonio Carlos ^[2] ; de Freitas, Natalia Lourenco ^[2] ; Viana, Patrik Ferreira ^[4] ; Yano, Cassia Fernanda ^[2] ; Hatanaka, Terumi ^[2] ; Marinho, Manoela Maria Ferreira ^[5] ; de Moraes, Renata Luiza Rosa ^[2] ; Feldberg, Eliana ^[4] ; Cioffi, Marcelo de Bello ^[2]

Affiliation

^[1] Czech Acad Sci, Lab Fish Genet, Inst Anim Physiol & Genet, Rumburska 89, Libechov 27721 - Czech Republic

^[2] Univ Fed Sao Carlos, Dept Genet & Evolucao, BR-13565905 Sao Paulo - Brazil

^[3] Secretaria Estado Educ Mato Grosso SEDUC MT, BR-78049909 Cuiaba - Brazil

^[4] Inst Nacl de Pesquisas da Amazonia, Coordenacao Biodiversidade, Ave Andre Araujo 2936, BR-69067375 Manaus, Amazonas - Brazil

^[5] Univ Fed Paraiba UFPB, DSE, Lab Sistemat & Morfol Peixes, BR-58051090 Joao Pessoa, Paraiba - Brazil

• Document type: Journal article
• Source: GENES; v. 11, n. 1 JAN 2020.
• Web of Science Citations: 0

Abstract

Lebiasinidae is a Neotropical freshwater family widely distributed throughout South and Central America. Due to their often very small body size, Lebiasinidae species are cytogenetically challenging and hence largely underexplored. However, the available but limited karyotype data already suggested a high interspecific variability in the diploid chromosome number (2n), which is pronounced in the speciose genus Nannostomus, a popular taxon in ornamental fish trade due to its remarkable body coloration. Aiming to more deeply examine the karyotype diversification in Nannostomus, we combined conventional cytogenetics (Giemsa-staining and C-banding) with the chromosomal mapping of tandemly repeated 5S and 18S rDNA clusters and with interspecific comparative genomic hybridization (CGH) to investigate genomes of four representative Nannostomus species: N. beckfordi, N. eques, N. marginatus, and N. unifasciatus. Our data showed a remarkable variability in 2n, ranging from 2n = 22 in N. unifasciatus (karyotype composed exclusively of metacentrics/submetacentrics) to 2n = 44 in N. beckfordi (karyotype composed entirely of acrocentrics). On the other hand, patterns of 18S and 5S rDNA distribution in the analyzed karyotypes remained rather conservative, with only two 18S and two to four 5S rDNA sites. In view of the mostly unchanged number of chromosome arms (FN = 44) in all but one species (N. eques; FN = 36), and with respect to the current phylogenetic hypothesis, we propose Robertsonian translocations to be a significant contributor to the karyotype differentiation in (at least herein studied) Nannostomus species. Interspecific comparative genome hybridization (CGH) using whole genomic DNAs mapped against the chromosome background of N. beckfordi found a moderate divergence in the repetitive DNA content among the species' genomes. Collectively, our data suggest that the karyotype differentiation in Nannostomus has been largely driven by major structural rearrangements, accompanied by only low to moderate dynamics of repetitive DNA at the sub-chromosomal level. Possible mechanisms and factors behind the elevated tolerance to such a rate of karyotype change in Nannostomus are discussed. (AU)

• FAPESP's process: 17/09321-5 - Miniature Characiformes (Teleostei: Ostariophysi): evolution, diversity and biogeography
• Grantee: Manoela Maria Marinho Koh
• Support Opportunities: BIOTA-FAPESP Program - Young Investigators Grants
• FAPESP's process: 18/24235-0 - Karyotype and sex chromosome evolution in Neotropical fishes. Part III.
• Grantee: Luiz Antonio Carlos Bertollo
• Support Opportunities: Regular Research Grants