Cytogenetic variation of repetitive DNA elements in Hoplias malabaricus (Characiformes - Erythrinidae) from white, black and clear water rivers of the Amazon basin

Abstract

Hoplias malabaricus is a common fish species occurring in white, black and clear water rivers of the Amazon basin. Its large distribution across distinct aquatic environments can pose stressful conditions for dispersal and creates possibilities for the emergence of local adaptive profiles. We investigated the chromosomal localization of repetitive DNA markers (constitutive heterochromatin, rDNA and the transposable element REX-3) in populations from the Amazonas river (white water), the Negro river (black water) and the Tapajós river (clear water), in order to address the variation/association of cytogenomic features and environmental conditions. We found a conserved karyotypic macrostructure with a diploid number of 40 chromosomes (20 metacentrics + 20 submetacentrics) in all the samples. Heteromorphism in pair 14 was detected as evidence for the initial differentiation of an XX/XY system. Minor differences detected in the amount of repetitive DNA markers are interpreted as possible signatures of local adaptations to distinct aquatic environments.

Genomic Organization of Repetitive DNAs and Differentiation of an XX/XY Sex Chromosome System in the Amazonian Puffer Fish, <b><i>Colomesus asellus </i></b>(Tetraodontiformes)

“…Different types of Amazonian environments with unique physicochemical characteristics (e.g., types of water) seem to drive a particular differentiation with accumulation of repetitive sequences in several fish species, probably reflecting processes of local adaptation [Gross et al, 2009;Santos et al, 2016]. However, it is plausible that these differences are due to non-migratory behavior or even divergence processes in isolated populations [Guimarães et al, 2017] We identified a karyotype with 2n = 46 and a heteromorphic XX/XY sex chromosome system in C. asellus .…”

Caracterização Cromossômica de Hoplias malabaricus (Characiformes: Erythrinidae) da Bacia do Rio Madeira, Rondônia

“…Tal fato corrobora com o proposto em Bertollo et al (2000), que sugerem a ocorrência de diferentes cariomorfos em simpatria. O cariomorfo C (2n=40) é o mais predominante na Amazônia e América do Sul, embora, características específicas quanto morfologia dos cromossomos, tenham sido observadas em populações com esse cariomorfo (Bertollo et al, 1997;Bertollo et al, 2000;Santos et al, 2016;Marques et al, 2013;Guimarães et al, 2017).…”

“…É possível que essas peculiaridades das formas cariotípicas encontradas em populações de diferentes bacias hidrográficas possam estar relacionadas às características específicas de suas respectivas áreas de origem, pois sabe-se que a bacia Amazônica é detentora de grande diversidade de ambientes, que exerce papel importante nos processos adaptativos dos organismos que nela habitam (Junk et al, 1989). Santos et al (2016), através da caracterização cromossômica de populações de H. malabaricus provenientes de ambientes de água branca, água clara e água preta da bacia amazônica, observou que a variação citogenômica tinha associação com os processos adaptativos locais da espécie a diferentes condições ambientais.…”

A new species of Hoplias malabaricus species complex (Characiformes: Erythrinidae) from the Crepori River, Amazon basin, Brazil

“…H. malabaricus (Bloch, 1794), distinguished from congeners by a characteristic rough tongue and V‐shaped margins of medial contralateral dentaries converging towards the symphysis in the ventral view of head (Oyakawa, 1990; Oyakawa & Mattox, 2009), was revealed to hide a species complex that was firstly evidenced by karyotypic variation (Bertollo et al ., 2000; Blanco et al ., 2009; Santos et al ., 2016). Molecular data appended evidence supporting the H. malabaricus complex (Dergam et al ., 1998; Jacobina et al ., 2018; Marques et al ., 2013; Pereira et al ., 2013; Rosso et al ., 2012).…”