The role of the Robertsonian rearrangements in the origin of the XX/XY1Y2 sex chromosome system and in the chromosomal differentiation in Harttia species (Siluriformes, Loricariidae)

Chromosomal distribution of the retroelements Rex 1, Rex 3 and Rex 6 in species of the genus Harttia and Hypostomus (Siluriformes: Loricariidae)

“…The analyses with nuclear and mitochondrial molecular markers, showed a close proximity between H. carvalhoi and H. torrenticola, to the point that these species represent a monophyletic clade (Costa-Silva, 2009). Posteriorly, this proximity between the two species was confirmed through chromosomal markers (Blanco et al, 2013). These authors attribute to the centric fission of the largest metacentric pair, which was shared only between these two species, as the event responsible for the origin of the system of sex chromosomes XX/XY 1 Y 2 present in H. carvalhoi.…”

“…This hypothesis is based on two facts: (i) these RTEs are shared by all Loricariidae previously analyzed (Ferreira et al, 2011b;Pansonato-Alves et al, 2013;Silva et al, 2014;Favarato et al, 2016) and Hypostomus (analyzed in this study), therefore, the invasion in the genome of Harttia is prior to the emergence of the clade and; (ii) the pair 23 is the only chromosome pair free from invasion of the Rex elements in this species. In H. torrenticola, was not detected the presence of Rex elements tested in the heterochromatic block in the terminal position of the long arm of the largest acrocentric pair 22 (Blanco et al, 2013).…”

“…Harttia is a genus of the subfamily Loricariinae that has 26 valid species (Fricke et al, 2019). Of these, only eight species present cytogenetic data (Alves et al, 2003;Kavalco et al, 2005;Centofante et al, 2006;Rodrigues, 2010;Blanco et al, 2012aBlanco et al, , 2013Blanco et al, , 2014Blanco et al, , 2017. The genus Harttia has conspicuous karyotype diversity, with diploid numbers (2n) ranging from 52 chromosomes in Harttia carvalhoi Miranda Ribeiro, 1939 females (Centofante et al, 2006) to 62 chromosomes in Harttia absaberi Oyakawa, Fichberg & Langeani, 2013 (cited as Harttia sp.…”

Comparative Cytogenetics Among Three Sympatric Hypostomus Species (Siluriformes: Loricariidae): An Evolutionary Analysis in a High Endemic Region

“…Cytogenetic analysis evidenced 2n = 54 chromosomes as an ancestral characteristic in Loricariidae, since it was reported in the basal genera and in the sister group Trichomycteridae 47 . Karyotype analyses in Hypostomus have allowed well-defined evolutionary trends, as the occurrence of high variation in the 2n, due to chromosomal rearrangements, like centric fissions [12][13][14][15][16][17][18][19][20][40][41][42][43][44][45][46] , which could explain the increased 2n present in the H. commersoni (2n = 68 chromosomes), H. derbyi (2n = 68 chromosomes) and H. myersi (2n = 74 chromosomes). Chromosome variability in Hypostomus may be assessed by intraspecific variation of 2n, karyotype formula, heterochromatin localization, and number and localization of NORs sites 15,17,44 .…”

“…Chromosome variability at the intra-and interspecific level are detected in comparative cytogenetic studies [16][17][18] . In addition, recent cytogenetic data showed that evolutionary breakpoint regions clustered in repetitive DNA regions promoted genomic reshuffle and chromosome evolution in Loricariidae species [19][20][21][22][23][24][25] . Iguaçu River is an important tributary of Paraná River basin in the south region of Brazil and presents high endemism of its ichthyofauna due to the isolation caused by the formation of the Iguaçu waterfalls 22 Mya ago 26 .…”