Heterochromatin Polymorphism and Physical Mapping of 5S and 18S Ribosomal DNA in Four Populations ofHypostomus strigaticeps(Regan, 1907) from the Paraná River Basin, Brazil: Evolutionary and Environmental Correlation

Abstract

A cytogenetic analysis was performed on four populations of Hypostomus strigaticeps from the Paraná River basin, Brazil. Two populations were collected from the large channel river at the Itaipu reservoir area and the other two were from the upper stretches of tributaries of the Paraná River. All populations showed 2n=72 chromosomes (12m+12sm+18st+30a), intra- and interpopulation 18S rDNA site polymorphisms (two to three acrocentric chromosome pairs), and multiple 5S rDNA sites in three chromosome pairs (4, 21, and 28). C-banding revealed heterochromatin located in the centromere and pericentromere regions of most chromosome; however, large heterochromatic blocks (CMA3(-)/DAPI(+)) on the long arm of acrocentric chromosomes identified intra- and interpopulation polymorphism. The amount and distribution of heterochromatin seem to be correlated to biogeographical characteristics of H. strigaticeps along the Paraná River. Morphometric results also showed diversity among the populations, suggesting phenotypic plasticity of this species. Evolutionary, taxonomy, and biogeographical approaches with regard to H. strigaticeps and interrelationships in Hypostomus are discussed.

Studies in two allopatric populations of Hypostomus affinis (Steindachner, 1877): the role of mapping the ribosomal genes to understand the chromosome evolution of the group

“…The rRNA in eukaryotes presents as two subunits (one formed by 28S, 18S and 5.8S and another one formed by 5S) and their DNA sequences vary very slowly due to selective pressure, being considered highly conserved (Long and Dawid 1980). This allows the interspecific hybridization of the mentioned probes (obtained from Prochilodus argenteus and Megaleporinus elongatus ), with chromosomes of a wide variety of fishes, like Characiformes (de Marco Ferro et al 2001, Pazza et al 2006, da Silva et al 2016), Gymnotiformes (Fernandes et al 2017a, 2017b) Perciformes (Jacobina et al 2014, Argôlo and Affonso 2015, Oliveira et al 2015b), Siluriformes (Blanco et al 2014, Kantek et al 2015, Ribeiro et al 2015), including other species of Hypostomus (Kavalco et al 2004a, 2005, Traldi et al 2013, Baumgärtner et al 2014, Oliveira et al 2015a, Lara Kamei et al 2017). …”

“…This marker has been defined in only approximately a dozen species of the genus for some Neotropical populations (Kavalco et al 2004a, Mendes-Neto et al 2011, Traldi et al 2012, Pansonato-Alves et al 2013, Traldi et al 2013, Baumgärtner et al 2014, Bueno et al 2014, Rocha-Reis et al unpublished data). Similar results were observed for the distribution of constitutive heterochromatin, although this type of highly compacted DNA requires further examination.…”

Constitutive heterochromatin heteromorphism in the Neotropical armored catfish Hypostomus regani (Ihering, 1905) (Loricariidae, Hypostominae) from the Paraguay River basin (Mato Grosso do Sul, Brazil)

“…The presence of extensive heterochromatic blocks on only one chromosomal arm is an intriguing trait of the chromosome morphology found in some Hypostomus species. Heterochromatinization processes and/or an amplification of this region were suggested as an attempt to explain the heterochromatic chromosomal polymorphism in a population of Hypostomusiheringii Regan, 1908 (Traldi et al 2012), in H.strigaticeps (Baumgärtner et al 2014) and Hypostomuspropeplecostomus Linnaeus, 1758 (Oliveira et al 2015). Furthermore, the presence of transposable elements (TEs) has been confirmed in the heterochromatic regions of a number of fish species (Ferreira et al 2011), including two Hypostomus species (Pansonato-Alves et al 2013), which could explain the origin of the heteromorphic metacentric in H.regani .…”

“…In fish, the amount and position of the heterochromatic blocks have been related to the occurrence of chromosomal rearrangements or amplifications, especially during the origin and evolution of specific chromosomes, such as sex chromosomes and B chromosomes (Vicari et al 2010). However, although scarce, available data on the heterochromatin of Hypostomus species indicate a great diversity in its amount and constitution (Artoni and Bertollo 1999, Kavalco et al 2004, Bittencourt et al 2011a, Traldi et al 2012, Baumgärtner et al 2014, Kamei et al 2017).…”

Cytogenetic characterization of Hypostomus soniae Hollanda-Carvalho & Weber, 2004 from the Teles Pires River, southern Amazon basin: evidence of an early stage of an XX/XY sex chromosome system

“…A number of cytogenetic studies have examined various aspects of the differentiation of the Hypostomus karyotype, including complex karyotype evolution (Martinez et al 2011; Alves et al 2012; Pansonato-Alves et al 2013; Bueno et al 2014), heterochromatin polymorphism (Traldi et al 2012; Baumgärtner et al 2014), inter-individual chromosome polymorphism (Artoni and Bertollo 1999; Ferreira et al 2019), and morphologically differentiated sex chromosomes (Artoni et al 1998; Oliveira et al 2015; Kamei et al 2017). A range of sex chromosome systems found in 705 fish species are available in the Tree of Sex Consortium (2014) database.…”