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Karyotypic diversification in Hoplias malabaricus (Osteichthyes, Erythrinidae) of the Sao Francisco and Alto Parana basins, Brazil

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... K A RY OT Y P I C DATA Karyomorph 2n = 40F In addition to specimens from Tombadouro Creek, all samples from the São Francisco drainage shared the same karyomorphic formula, which is considered to be characteristic for São Francisco basin populations (Bertollo et al., 2000 ). The distributional pattern of heterochromatin was similar to that described by Dergam & Bertollo (1990) for the Três Marias population in this basin (Fig. 1), except for the presence of a heterochromatic block that was always restricted to one homologue of the first chromosome pair in males. This pattern suggested a probable XX/XY sex chromosome system in these populations, because this variant occurred only in males and was absent in females. ...
... C-positive heterochromatic bands were always located in the centromeric/ pericentromeric region of all chromosomes and in the telomeric region of some pairs, in addition to multiple Ag-NORs sites. These heterochromatic and NOR characteristics were similar to those reported for other populations or karyomorphs of H. malabaricus (Dergam & Bertollo, 1990; Haaf et al., 1993; Bertollo, 1996 Bertollo, , 1997 Vicari et al., 2003 Vicari et al., , 2005). In the Pandeiros River sample, Ag-NORs were restricted to telomeres of some chromosomes and appeared in larger numbers than 18S rDNA sites, but the latter also hybridized to the pericentromeric region of one chromosome pair [Fig. ...
... 3(a)]. There is currently no explanation for the apparently non-specific nature of some telomeric Ag-NORs in the Pandeiros sample, which is as large as seven in the Três Marias region (Dergam & Bertollo, 1990). On the other hand, pericentromeric 18S rDNA sites were not visualized by the silver nitrate method (these data and Dergam & Bertollo, 1990), which may be due to preferential telomeric NOR activation, as already pointed out for other Hoplias spp. ...
Article
The sedentary, predatory characin Hoplias malabaricus has one of the widest distributions of freshwater fishes in South America and is characterized by seven karyomorphs (A-G) that occur in sympatric and allopatric populations. Karyotypical patterns of variation in wild populations have been interpreted as evidence of multiple lineages within this nominal species, a possibility that may limit the validity of experimental data for particular karyomorphs. This study used the phylogeographic and genealogical concordance between cytogenetic (N = 49) and molecular (mitochondrial DNA) (N = 73) data on 17 samples, collected in 12 basins from south-eastern and north-eastern Brazil, to assess the systematic value of cytogenetic data. Cytogenetic patterns show a sex chromosome system in the 2n = 40F karyomorph. Molecular and cytogenetic data indicate a long, independent evolutionary history of karyomorphs and a coastal origin of continental populations in south-eastern Brazil. The lack of fit with molecular clock expectations of divergence between groups is likely to be due to strong demographic fluctuations during the evolution of this species complex. The results indicate that karyotypical identification provides a reliable baseline for placing experimental studies on Hoplias spp. in a phylogenetic context.
... Despite the differences that distinguish karyomorphs, the distribution of heterochromatin and nucleolar organizer regions (Ag-NOR) are quite similar between and within populations. The blocks of constitutive heterochromatin are usually located in centromeric and pericentromeric regions of all chromosomes and in telomeric regions of some pairs (Dergam & Bertollo, 1990; Bertollo et al., 1997; Vicari et al., 2005). The Ag-NORs are present in several chromosomes, with the maximum number of 10 chromosomes; some populations have such sites on telomeres of both chromosome (bitelomeric Ag-NORs) (Bertollo, 1996). ...
... ric sequence of satellite DNA specific to H. malabaricus, now known as 5SHind III-DNA. This sequence is very similar to 5S ribosomal DNA (rDNA), however, while the 5S rDNA sites appear in the interstitial region of up to two chromosome pairs, the sites of 5SHind III-DNA appear in the centromeric region of up to 22 chromosomes (Cioffi et al., 2009). Dergam & Bertollo (1990) hypothesized that such different karyotypes might characterize different species, since the different karyotypic forms can be found in sympatric conditions without the occurrence of hybrid karyotypes (Bertollo et al., 1997; Dergam et al., 1998; Born & Bertollo, 2006). Therefore, it is evident that, according to the species concept to be ...
... 1(c) ] found here, follows the pattern described in H. malabaricus. This characteristic seems to be shared by all populations of H. malabaricus studied to date (Dergam & Bertollo, 1990; Bertollo et al., 1997; Vicari et al., 2005). The band pattern produced by CMA 3 is coincident with some heterochromatic blocks, especially those associated with Ag-NORs. ...
Article
Cytogenetic markers were used to compare the karyotypes of an isolated population of Hoplias malabaricus with others previously described. The results revealed peculiar characteristics that indicate a new independent evolutionary unit within the H. malabaricus complex.
... Although usually considered as a single biological species, the taxonomy of this group is poorly understood (Oyakawa 1990). Growing evi-dence has pointed to the karyotypic diversity of H. malabaricus, showing interpopulational differences in the diploid number and chromosome morphology, as well as in sex chromosome systems (Bertollo et al. 1979, 1983, Ferreira et al. 1989, Dergam & Bertollo 1990, Scavone et al. 1994, Lopes & Fenocchio 1994, Bertollo et al. 1997a, 1997b, Lopes et al. 1998, Bertollo & Mestriner 1998, Born & Bertollo 2000. ...
... In this paper, we provide an overview of the karyological diversity in Hoplias malabaricus, with the description of a new cytotype from the Amazon basin and the comparative analysis of the several known cytotypes, their geographic distributions and sympatric regions, compiled from our studies with this ¢sh group over the last two decades. The available karyotypic data for Hoplias malabaricus have led to the hypothesis that this ¢sh represents a species complex (Bertollo et al. 1986, Dergam & Bertollo 1990, Bertollo et al. 1997a, Lopes et al. 1998; this is reinforced by the present study. ...
... n Number of specimens studied; Brazilian States in brackets: AM: Amazonas; GO: Goia¨s; MA: Maranha¬ o; MG: Minas Gerais; MS: Mato Grosso do Sul; MT: Mato Grosso; PA: Para¨; PE: Pernambuco; PR: Parana¨; RN: Rio Grande do Norte; RO: Rondoª nia; RS: Rio Grande do Sul; SC: Santa Catarina; SP: Sa¬ o Paulo. References: 1. Bertollo et al. (1997a); 2. Present paper; 3.Lopes & Fenocchio (1994); 4.Lopes et al. (1998); 5. Jorge (1995); 6.Bertollo et al. (1983); 7.Dergam & Bertollo (1990); 8.Bertollo et al. (1997b); 9.Scavone et al. (1994); 10.Dergam (1996); 11. Born (unpublished); 12.Bertollo et al. (1979); 13.Ferreira et al. (1989); 14. ...
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Hoplias malabaricus, a widely distributed neotropical freshwater fish, shows a conspicuous karyotypic diversification. An overview of this diversity is presented here comprising several Brazilian populations, and some others from Argentina, Uruguay and Surinam. Seven general cytotypes are clearly identified on the basis of their diploid number (2n = 39 to 2n = 42), chromosomal morphology and sex chromosome systems, which can be clustered into two major karyotypic groups. This clustering suggests that karyotype structure would be more informative than the diploid number regarding cytotype relationships in this fish group. While some cytotypes show a wide geographical distribution, some others appear to be endemic to specific hydrographic basins. Sympatric cytotypes can occur without detection of hybrid forms; this situation points to a lack of gene flow, a fact that is also reinforced by studies with genomic markers. The karyotypic data support the view that the nominal taxon H. malabaricus corresponds to a species complex comprising distinct evolutionary units, each with well-established chromosomal differences.
... Hoplias malabaricus represents one of the neotropical ®sh groups that are widely distributed in Latin America currently being extensively studied from the cytogenetic viewpoint. Populations with different karyotypes have been described, with differences in chromosome number , structure and sex chromosome system (Bertollo et al. 1979, 1983, Dergam & Bertollo 1990). These cytotypes may represent a group of distinct species with species-speci®c karyotypes (Bertollo et al. 1997). ...
... However, X 1 and X 2 are arbitrary denominations as they do not refer to the original X chromosome (X 1 ) or to the new X (X 2 ) resulting from the establishment of the system. Although later studies have con®rmed the multiple sex chromosome system in the same cytotype of Hoplias malabaricus (Dergam & Bertollo 1990, Scavone et al. 1994), the identi®cation of the sex chromosomes in the karyotype was not always certain. In the present investigation, complementary analyses with G-, C-and replication banding led us to better characterize the sex chromosomes and the process involved in the evolution of the sex chromosome system. ...
... However, banding techniques used in this study identi®ed several chromosomal pairs in the H. malabaricus karyotype, with particularly good results for sex chromosome characterization. C-banding results were similar to those obtained by Dergam & Bertollo (1990) and Haaf et al. (1993) for this same species. Small centromeric heterochromatic bands occur in practically all chromosomal pairs. ...
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Hoplias malabaricus, a widely distributed neotropical fish (Central America to Argentina), may represent a group of distinct species showing diversified cytotypes with respect to chromosome number, morphology and sex systems. One of these karyotypic forms is characterized by an X1X1X2X2/X1X2Y sex chromosome system, with 2n = 40 and 39 chromosomes in females and males respectively. Analyses with G-, C- and chromosome replication banding permitted a better characterization of the sex chromosomes in this cytotype. The Y chromosome, unique in males, resulted from a translocation event between two biarmed chromosomes: one similar to chromosome 6 (X1) and the other one similar to chromosome 20 (X2), the latter corresponding to a probable identification. On the basis of the observed banding patterns, the Y chromosome may represent a stable dicentric, with an inactive centromere interstitially located on its long arm. The results are also related to a specific satellite DNA subfamily, previously characterized in Hoplias malabaricus, which appears to be associated with the X1 chromosome.
... Despite the differences that distinguish karyomorphs, the distribution of heterochromatin and nucleolar organizer regions (Ag-NOR) are quite similar between and within populations. The blocks of constitutive heterochromatin are usually located in centromeric and pericentromeric regions of all chromosomes and in telomeric regions of some pairs (Dergam & Bertollo, 1990;Bertollo et al., 1997;Vicari et al., 2005). The Ag-NORs are present in several chromosomes, with the maximum number of 10 chromosomes; some populations have such sites on telomeres of both chromosome (bitelomeric Ag-NORs) (Bertollo, 1996). ...
... This sequence is very similar to 5S ribosomal DNA (rDNA), however, while the 5S rDNA sites appear in the interstitial region of up to two chromosome pairs, the sites of 5SHind III-DNA appear in the centromeric region of up to 22 chromosomes (Cioffi et al., 2009). Dergam & Bertollo (1990) hypothesized that such different karyotypes might characterize different species, since the different karyotypic forms can be found in sympatric conditions without the occurrence of hybrid karyotypes (Bertollo et al., 1997;Dergam et al., 1998;Born & Bertollo, 2006). Therefore, it is evident that, according to the species concept to be adopted, different karyomorphs described for H. 'of the group' malabaricus may reflect the existence of cryptic taxa with specific karyotypes (Bertollo et al., 1997. ...
... The distribution of constitutive heterochromatin including pericentromeric and telomeric blocks, as well as those related to the sites of nucleolar organization [ Fig. 1(c)] found here, follows the pattern described in H. malabaricus. This characteristic seems to be shared by all populations of H. malabaricus studied to date (Dergam & Bertollo, 1990;Bertollo et al., 1997;Vicari et al., 2005). ...
... Having diploid numbers ranging from 2n = 16 to 2n = 250 chromosomes (DENTON 1973;Kl:RPCHINIKOV 1981), fish can be considered one of the animal groups with the widest variation in karyotype. ...
... Those taxa, such as Hoplias and Astyanax, which show a heterogeneous pattern of chromosome evolution are characterized by extensive numerical and structural variations of karyotypes (Tables 1 and 2). Robertsonian and non-Robertsonian chromosome rearrangements appear to be equally involved in BERTOLLO (1990) H. c£. ma/abaricus 40(b) biarmed BERTOLLO et aJ. ...
Article
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Neotropical characiform fishes present two main trends of chromosomal evolution: some taxa show a heterogeneous pattern, with an extensive numerical and structural variation while others show a more homogeneous one, with a clear stability in their karyotype macrostructure. The implications of the populational features and some other conditions to these two general paths are discussed.
... Several H. malabaricus populations have been cytogenetically analyzed throughout the geographic distribution of this species. Until now, 7 karyomorphs (A-G) were easily discriminated, 3 of them (B, D and G) with distinct sex chromosome systems [Bertollo et al., 1983[Bertollo et al., , 1997aDergam and Bertollo, 1990;Bertollo and Mestriner, 1998;Born and Bertollo, 2000), appearing to characterize species-specific karyotypes. The 3 populations analyzed belong to karyomorph A, exhibiting a diploid number of 2n = 42 and a karyotype with 22 m and 20 sm chromosomes, without heteromorphic sex chromosomes. ...
... Indeed, the C-positive heterochromatic bands were always located in the centromeric/pericentromeric region of all chromosomes and in the telomeric region of some pairs, in addition to multiple Ag-NOR sites. These heterochromatic and NOR characteristics also fit the general patterns that have been documented for other populations or karyomorphs of H. malabaricus [Dergam and Bertollo, 1990;Haaf et al., 1993;Bertollo, 1996;Bertollo et al., 1997a, b;Born and Bertollo, 2000;Vicari et al., 2003Vicari et al., , 2005. As a whole, all of the aforementioned similarities indicate that the 3 populations belong to the same karyomorph group in close proximity, despite the distinct river basins of origin. ...
Article
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Karyotype and chromosomal characteristics from 3 allopatric populations of Hoplias malabaricus, cytogenetically the most studied Erythrinidae taxon, were investigated using different staining techniques (C-, Ag-, and CMA(3) banding) as well as fluorescent in situ hybridization (FISH) to detect 18S rDNA, 5S rDNA, and 5SHindIII satellite DNA sites. The isolation, cloning and characterization of an 18S rDNA probe from H. malabaricus genome were also performed for the first time in order to develop a more specific probe. The 3 populations, named PR, CR, and DR, showed identical karyotypes, with 2n = 42 chromosomes composed of 11 m pairs and 10 sm pairs, without heteromorphic sex chromosomes, which characterize the populations as belonging to karyomorph A. In all populations C-positive heterochromatin was situated in the centromeric/pericentromeric regions of the chromosomes, as well as in the telomeric region of several pairs. A conspicuous proximal heterochromatic block on the long arm of pair No. 16 was the only GC-rich segment in the karyotypes. 5SHindIII satellite DNA was always mapped in the centromeric region of several chromosomes. The 18S rDNA sites were situated on the telomeric or centromeric regions, whereas the 5S rDNA showed an interstitial or proximal location in some pairs. Several chromosomes bearing these repetitive DNA sequences were shared by the 3 populations, alongside with some exclusive chromosomal markers. In this sense, population CR was the most differentiated one, including a syntenic condition for the 18S and 5S rDNA probes, as confirmed by double FISH. Thus, despite their inclusion in the same major karyotypic group, the distinct populations cannot be considered an absolute evolutionary unit, as evidenced by their inner chromosomal differentiations.
... Conforme a esta clasificación, los ejemplares de H. malabaricus estudiados en el presente trabajo forma� rían parte del citotipo C (grupo I), caracterizado por presentar un número diploide (2n) igual a 40 cromoso� mas en ambos sexos, con un cariotipo constituido por 15 pares M y 5 pares SM, todos ellos identificados por mediciones cromosómicas, con un número fundamen� tal (NF) igual a 80 (Figura 1a). En los individuos ana� lizados no se observó ningún sistema de cromosomas sexuales, siendo éstos identificados en algunas pobla� ciones de H. malabaricus de Brasil 3,[8][9][10][11]13 . ...
... En otros trabajos, la heterocromatina constitutiva mostró una distribución patrón en todas las poblacio� nes analizadas de H. malabaricus 6,7,10,11,13,14,19 , siendo pericentromérica en todos los cromosomas del comple� mento y telomérica en algunos cromosomas; esta últi� ma condición fue semejante a la hallada en la población aquí estudiada. ...
Article
Hoplias malabaricus has a wide geographical distribution, being found in several river basins in neotropical regions of South American countries, where is considered a valuable resource. Due to its karyotype diversity, the aim of this study was to analyze the chromosomal structure of this species, from the Riachuelo River, tributary of the Paraná River in Corrientes, Northeastern Argentina. The population had a diploid number (2n) of 40 meta-submetacentric chromosomes, cited as "cytotype C" in previous research. There was no evidence of any type of sex chromosomes. C banding by constitutive heterochromatin was located in pericentromeric and telomeric position. By means of the silver nitrate staining it was observed Ag-NOR positive bearings in the telomeric region of six chromosomes of the complement. The results provide additional information to the existing literature, corroborating the hypothesis that H. malabaricus is part of a complex of species.
... malabaricus (Bloch, 1794), popularmente conhecida como traíra, apresenta ampla distribuição geográfica, ocorrendo na maior parte das bacias hidrográficas da América do Sul (Gery, 1977). A traíra é uma excelente representante da diversidade cariotípica dos Characiformes, acredita-se que ela não seja formada por uma única espécie, mas sim por um complexo de espécies, com pelo menos cinco citótipos diferentes com o número de cromossomos variando de 39 a 42 (Dergam & Bertollo, 1990). Maniglia et al. (2000) relacionaram os citótipos e a variabilidade genética de oito indivíduos da planície de inundação do alto rio Paraná, e os resultados demonstraram que H. aff. ...
... Embora dados citogenéticos (Dergam & Bertollo, 1990) e de marcadores moleculares RAPD-PCR (Dergam et al., 1998;Maniglia et al., 2000) sugiram a existência de um complexo de espécies para H. aff. malabaricus, no presente estudo não foram detectadas alterações na expressão dos quatorze sistemas enzimáticos testados neste estudo que corroborem com esta hipótese. ...
Article
RESUMO A variabilidade genética em Hoplias aff. malabaricus, de duas localidades da planície de inundação do alto rio Paraná, foi investigada por eletroforese de gel de amido e poliacrilamida. Um total de 52 espécimes foram analisados para 14 sistemas enzimáticos. Um total de 24 loci gênicos foram detectados. Quando os valores de heterozigosidade de H. aff. malabaricus são comparados com outras espécies da bacia do rio Paraná, encontramos alta variabilidade genética (H e = 0.14). A espécie apresentou a mesma variabilidade genética para os dois ambientes (fluvial e lacustre), entretanto elas diferem significativamente nas frequências gênicas (P < 0.05) . Palavras chaves: isoenzimas, planície de inundação, variabilidade genética, polimorfismo. INTRODUÇÃO A eletroforese de enzimas tem sido utilizada em genética de populações como uma ferramenta para estimar a variabilidade genética de populações naturais desde o trabalho pioneiro de Hubby & Lewontin (1966). Em peixes, os resultados assim obtidos têm sido aplicados a estudos evolutivos (Powers & Schulte, 1998), taxonômicos (Almeida & Sodré, 1998; Chiari & Sodré, 1999), filogenéticos (Zawadzki, 2001), bem como a delimitação de estoques de espécies exploradas comercialmente (Revaldaves et al., 1997). Os estudos de genética de populações procuram entender como as variações na taxa de sobrevivência, reprodução e crescimento contribuem para as alterações nas freqüências gênicas e genotípicas das populações e se estas alterações conferem maior valor adaptativo as espécies. Fatores como reprodução, migração, deriva genética e seleção natural são de extrema importância para o processo de adaptação a circunstâncias ecológicas particulares (Kirpichnikov, 1992).
... On the other hand, in G. pantanal [27], G. jonasi [22] and G. coatesi [28] the NORs are multiple (more than one pair). A common evolutionary interpretation of this variation is attributed to Hsu et al. [29] who assume that a single NOR pair is a primitive (plesiomorphic) condition while multiple NORs are a derived (apomorphic) trait [16,30313233. For this hypothesis to be correct two conditions must be achieved: 1) for species with a single NOR the NOR-bearing chromosomes must be homeologous in the different species within the same taxonomic group. ...
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Gymnotus (Gymnotiformes, Gymnotidae) is the most diverse known Neotropical electric knife fish genus. Cytogenetic studies in Gymnotus demonstrate a huge karyotypic diversity for this genus, with diploid numbers ranging from 34 to 54. The NOR are also variable in this genus, with both single and multiple NORs described. A common interpretation is that the single NOR pair is a primitive trait while multiple NORs are derivative. However this hypothesis has never been fully tested. In this report we checked if the NOR-bearing chromosome and the rDNA site are homeologous in different species of the genus Gymnotus: G. carapo (2n = 40, 42, 54), G. mamiraua (2n = 54), G. arapaima (2n = 44), G. sylvius (2n = 40), G. inaequilabiatus (2n = 54) and G. capanema (2n = 34), from the monophyletic group G. carapo (Gymnotidae-Gymnotiformes), as well as G. jonasi (2n = 52), belonging to the G1 group. They were analyzed with Fluorescence in situ hybridization (FISH) using 18S rDNA and whole chromosome probes of the NOR-bearing chromosome 20 (GCA20) of G. carapo (cytotype 2n = 42), obtained by Fluorescence Activated Cell Sorting. All species of the monophyletic G. carapo group show the NOR in the same single pair, confirmed by hybridization with CGA20 whole chromosome probe. In G. jonasi the NORs are multiple, and located on pairs 9, 10 and 11. In G. jonasi the GCA20 chromosome probe paints the distal half of the long arm of pair 7, which is not a NOR-bearing chromosome. Thus these rDNA sequences are not always in the homeologous chromosomes in different species thus giving no support to the hypothesis that single NOR pairs are primitive traits while multiple NORs are derived. The separation of groups of species in the genus Gymnotus proposed by phylogenies with morphologic and molecular data is supported by our cytogenetic data.
... Cytogenetic descriptions of Bryconinae are restricted to eight species that occur in the Amazon, São Francisco and Paraná watersheds [13] and one species in the Paraíba do Sul drainage. Historically, cytogenetic data on Ostariophysan fish have allowed the identification of cryptic species [14], the characterization of populations [15,16], and the formulation of phylogenetic and phylogeographic hypotheses171819. This study reports the first cytogenetic data for H. wheatlandii and compares the results with other species of Bryconinae from a biogeographic and phylogenetic perspective. ...
Article
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Henochilus wheatlandii, the only species of this genus, is critically endangered and was considered extinct for over a century. The rediscovery of this fish in 1996 made it possible to study its phylogenetic relationships with other species in the subfamily Bryconinae. The aim of this study was to characterise the karyotype of H. wheatlandii. Standard staining, C-positive heterochromatin and nucleolar organiser region (NOR) banding, chromomycin A(3) staining, and fluorescent in situ hybridisation (FISH) using 5S rDNA and 18S rDNA probes were conducted on nineteen specimens collected in the Santo Antonio River, a sub-basin of the Doce River in Ferros municipality, Minas Gerais State, Brazil. Henochilus wheatlandii shared the same diploid number and chromosome morphology as other species of Bryconinae. However, its heterochromatin distribution patterns, NOR localisation, and FISH patterns revealed a cytogenetic profile unique among Neotropical Bryconinae, emphasizing the evolutionary uniqueness of this threatened species.
... The erythrinids have been subjects of phylogenetic studies due to particular behavioural and morphological characteristics within the Characiformes, show- ing them to be related to primitive characiforms (Buckup, 1998;Calcagnoto et al., 2005). Hoplias malabaricus (Bloch), the most widespread species of the group, shows a conspicuous karyotypic diversity indicating a species-complex comprising distinct evolutionary units in South America, each with well- established chromosomal differences (Dergam & Bertollo, 1990;Bertollo et al., 2000;Vicari et al., 2005). ...
Article
Oocyte morphology, embryogenesis and early larval development were compared in Hoplerythrinus unitaeniatus, Hoplias lacerdae and Hoplias malabaricus (Characiformes: Erythrinidae) by macroscopical, histological, histochemical and ultrastructural analyses. The eggs of the three species were yellowish and adhesive, containing carboxyl and sulphate radicals in the glycoconjugates of the zona radiata. A complex surface arrangement was identified in oocytes of H. unitaeniatus and H. lacerdae, while H. malabaricus had a simple oocyte surface pattern. Lectin histochemistry revealed different carbohydrate terminal residues in cortical alveoli, outer zona radiata and follicular cells of the three species. At the animal pole, the oocyte surface topography surrounding the micropyle was species-specific. The micropylar cell was ConA-positive, suggesting the presence of carbohydrates with mannose/glucose terminal residues that could have a role during fertilization. The erythrinids exhibited a prolonged embryonic and larval development compared to other Characiformes, a reproductive strategy used for increasing offspring protection. Early development proceeded most rapidly in H. unitaeniatus, followed by H. malabaricus and then H. lacerdae, which could have more developed parental care behaviour. An adhesive organ composed of secretory prismatic cells protruding from the cephalic region of the three erythrinid larva allowed them to attach to one another during development. Reproductive behaviour and early developmental strategies were similar in the three species, but the oocyte surface morphology suggests a close relationship between H. unitaeniatus and H. lacerdae.
... ZZ/ZW systems are more frequent and occur in a diversity of families, such as Anostomidae (Galetti et al. 1981; Venere et al. 2004), Prochilodontidae (Feldberg et al. 1987), Characidae (Bertollo and Cavallaro 1992; Maistro et al. 1998) and Parodontidae (Moreira-Filho et al. 1993; Centofante et al. 2002 ) in Characiformes, and Poeciliidae in Cyprinodontiformes (Haaf and Schmid 1984). Multiple systems have been documented in Characiformes of the families Parodontidae (Moreira-Filho et al. 1980) and Erythrinidae (Bertollo et al. 1983; Dergam and Bertollo 1990; Bertollo et al. 1997; Bertollo and Mestriner 1998 Gymnotiformes of the families Sternopygidae ( Toledo et al. 1984 ) and Hypopomidae (Toledo et al. 2000). Although cytogenetic studies of the family Loricariidae have revealed the predominance of homomorphic sex chromosomes ( Alves et al. 2005; Kavalco et al. 2005), cases of simple and multiple systems of sex chromosomes have been described for this group. ...
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Loricariid catfishes show a predominance of homomorphism in sex chromosomes, but cases of simple and multiple systems were also found. Here we describe two cases of multiple sex chromosome systems in loricariids from Brazilian Amazonia. Males of Ancistrus sp.1 "Balbina" have a modal number of 2n = 39 chromosomes, fundamental number (FN) of 78, and karyotypic formula of 27 m + 10 sm + 2 st; females have 2n = 38 chromosomes, FN = 76, and 26 m + 10 sm + 2 st. Ancistrus sp.2 "Barcelos" has 2n = 52 chromosomes for both sexes, FN = 80 for males and FN = 79 for females. Karyotypic formula is 12 m + 12 sm + 4 st + 24a for males and 11 m + 12 sm + 4st + 25a for females. The two species show different arrangements of constitutive heterochromatin blocks, which are coincident with NORs and absent in sex chromosomes. We suggest a XX/XY(1)Y(2) mechanism for Ancistrus sp.1 "Balbina", and a Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) mechanism for Ancistrus sp.2 "Barcelos". The XX/XY(1)Y(2) mechanism here reported is the second known occurrence of this type of multiple sex chromosomes for Loricariidae and the third for Neotropical fishes; the mechanism Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) represents the first record among fishes. The presence of different sex chromosome systems in Ancistrus indicates a probable independent origin and suggests that the differentiation of sex chromosomes is evolutionarily recent among species in this genus.
... Although a correlation between organism and karyotype evolution is not always established, it seems plausible to consider that evolutionary mechanisms might have independently affected each cytotype/species through both particular environmental conditions (i.e., local selective pressure ) and the unique genomic features of each cytotype (karyotype formulae, heterochromatin amount and gene location ). Such disruptions among distinct evolutionary levels might have been responsible for the occurrence of cryptic fish species, like those detected in Hoplias (Bertollo et al., 1979; Dergam and Bertollo, 1990; Pazza and Julio Jr, 2003), Eigenmannia (Toledo et al., 1984Toledo et al., , 1985Toledo et al., , 1988 ) and, remarkably, in the genus Astyanax, this including A. hastatus. Therefore, the distinct cytotypes herein described should correspond to selection units, thus representing specific entities and composing, not a species complex, but a group of cryptic species, since each cytotype was precisely identified and the biological boundaries among analyzed specimens were supported by the cytogenetic markers used, thereby revealing the lack of hybrid forms. ...
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Four populations of Astyanax hastatus Myers 1928 from the Guapimirim River basin (Rio de Janeiro State) were analyzed and three distinct cytotypes identified. These cytotypes presented 2n = 50 chromosomes, with 4M+8SM+10ST+28A (Cytotype A), 8M+10SM+14ST+18A (Cytotype B), 6M+8SM+4ST+32A (Cytotype C) and scanty heterochromatin, mainly located throughout pericentromeric regions of several chromosomal pairs. No homologies with the As-51 satellite DNA were observed in the three cytotypes, although all of them presented multiple 18S rDNA sites, as detected by both silver nitrate staining and FISH (fluorescent in situ hybridization). The application of the term "species complex" in Astyanax is discussed from a cytotaxonomic viewpoint.
... The occurrence of distinct chromosomal mechanisms of sex differentiation in phylogenetically related groups is frequent in Neotropical fishes. This phenomenon has already been observed in several fish groups such as Parodontidae (Moreira-Filho et al., 1993;Jesus et al., 1999;Bellafronte et al., 2009), Erythrinidae (Bertollo et al., 1983;Dergan & Bertollo, 1990;Born & Bertollo, 2000) and Gymnotiformes (Almeida-Toledo et al., 2000. ...
Article
Comparative cytogenetic studies carried out in two populations of Characidium cf. gomesi from Botucatu region, SP, Brazil, showed a similar karyotypic structure in a diploid number of 50 chromosomes, 32 metacentric and 18 submetacentric chromosomes for males and 31 metacentric and 19 submetacentric chromosomes for females as well as a ZZ-ZW sex chromosome system. Differences between both populations, however, were found in relation to the occurrence of B chromosomes and the distribution of 18S and 5S ribosomal DNA (rDNA) sites. Characidium cf. gomesi from the Alambari Stream, a component of the Tietê River basin, revealed 18S rDNA on Z and W chromosomes, while this gene was located on autosomes in the sample from the Paranapanema River basin. The 5S rDNA sites were observed in a single chromosomal pair (number 25) in the populations from Paranapanema and in two pairs in the specimens from Tietê (numbers 20 and 25). Besides that, in the sample from Paranapanema, both inter and intra-individual variations were found due to the occurrence of up to four heterochromatic supernumerary chromosomes in the cells. The life mode of this fish, restricted to headwaters and subjected to frequent breakdown into sub-populations, may have contributed to the fixation of such chromosomal differences. The karyotypic similarities found in the analysed populations, however, suggest that all are descended from the same ancestor group whereas their differences indicate that they are already existing in reproductively isolated populations.
... Estudos citogenéticos com H. malabaricus se iniciaram com Bertollo et al. (1979) e, desde o princípio, tem se mostrado um grupo bem heterogêneo. Esse e outros trabalhos realizados em diferentes bacias hidrográficas da América do Sul, evidenciaram formas cariotípicas distintas entre as populações, com variações quanto ao número diploide (2n= 39/40 a 42), morfologia e presença/ausência de sistemas de cromossomos sexuais heteromórficos (Bertollo, 1983;Ferreira et al., 1989;Dergam & Bertollo, 1990;Lopes & Fenocchio, 1994;Scavone et al., 1994;Bertollo et al., 1997;Lopes et al., 1998;. Estudos posteriores com a espécie, concentraramse em entender diversificação do grupo e as relações evolutivas entre os cariomorfos, no entanto, novas variações cariotípicas foram identificadas (Born & Bertollo, 2006;Santos et al., 2010;Vitorino et al., 2011), como por exemplo, a unidade evolutiva independente de traíras do Médio Araguaia (Vitorino et al., 2011). ...
... Dergam et al. (1998) stated that the introduction of H. malabaricus in the Iguaçu river could have been done from the Tibagi headwaters, based on the similar genetic patterns of the populations, as well as in the proximity of both rivers. Cytogenetical data clearly indicate that H. malabaricus is a complex species, probably related to its wide distribution over Neotropical region, requiring a careful taxonomic revision ( Bertollo et al., 1983;Dergam and Bertollo, 1990;Scavone et al., 1994;Bertollo et al., 2000). Bertollo et al. (2000) differentiated seven distinct cytotypes in this fish group, based on their chromosome numbers and morphology and the absence or occurrence of distinct sex chromosome systems. ...
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Hoplias malabaricus (trahyra) is a widespread fish species over the Neotropical region with diversified inter-populational karyotypes (cytotypes), which may correspond to a species complex. Despite the wide distribution in the South American basins, some authors have questioned its natural origin in the Iguaçu river, an important Brazilian river basin which is characterized by several endemic fish species. We have analyzed the karyotype of H. malabaricus from different collection sites of this river, by conventional and banding methods. Our results, in addition to our previous data concerning geographic distribution of the cytotypes, contribute to better understand the origin of H. malabaricus on the Iguaçu river, reinforcing the proposition that it is a natural fish species in this river basin.
... H. malabaricus is an excellent representative of the karyotypic diversity of Characiformes. It consists of a complex of species with at least five cytotypes with the number of chromosomes varying from 39 to 42 (Dergam and Bertollo, 1990). Maniglia et al. (2000) listed the cytotypes and the genetic variability of eight individuals from the upper Paraná River floodplain. ...
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Genetic variability in Hoplias malabaricus, from two localities in the upper Paraná River floodplain, was investigated by starch and polyacrylamide gel electrophoresis. A total of 52 specimens were analyzed for 14 enzymatic systems. Twenty-three gene loci of 13 enzymatic systems (AAT, ACP, ADH, GDH, G6PDH, GPI, IDH, LDH, MDH, MEP, PGM, PER, and SOD) were analyzed by starch gel electrophoresis (Penetrose-30). The EST system was analyzed by polyacrylamide gel electrophoresis, and one polymorphic locus was found (EST-1). Twenty-four loci were detected. The proportion of polymorphic loci was 37.5% in the lagoon and 33.3% in the river. Significant differences in allele frequencies of five loci were found between specimens from the two environments. Expected mean heterozygosity (H e = 0.14) is the same in the river and lagoon, however, Nei's genetic distance (D) between the population of the two locations was 0.049.
... Of this genus, the species Hoplias malabaricus has been the most extensively analyzed. The available data clearly demonstrate a non-conservative chromosomal evolution in H. malabaricus, with evidence of a species complex for this nominal species (Bertollo et al., 1986;Dergam & Bertollo, 1990;Scavone et al., 1995;Lopes & Fenocchio, 1994;Lopes et al., 1998;Bertollo et al., 2000). ...
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Specimens of Hoplias malabaricus from Lagoa Carioca, an isolated lake of the Rio Doce State Park (state of Minas Gerais, Brazil), were cytogenetically studied. The diploid number was found to be constant, i.e., 2n = 42 chromosomes, although two karyotypic forms were found: karyotype A, characterized by 22M + 20SM chromosomes, observed only in a male specimen, and karyotype B, characterized by 24M + 16SM + 2ST and 24M + 17SM + 1ST chromosomes in female and male specimens, respectively. This sex difference found in karyotype B is related to an XX/XY sex chromosome system. Another female specimen of H. malabaricus, also carrying karyotype A, had previously been found in the same lake. The available data indicate that two sympatric cytotypes of H. malabaricus exist in the Lagoa Carioca, with cytotype A occurring at a lower frequency and differing from cytotype B by undifferentiated sex chromosomes.
... Although usually considered as a single biological species, the taxonomy of Hoplias malabaricus is poorly understood. Growing evidence has pointed to the karyotypic diversity of H. malabaricus, showing interpopulational differences in the diploid number and chromosome morphology, as well as in sex chromosome systems (Bertollo, Moreira-Filho, 1978, 1983; Dergam and Bertollo, 1990; Fontes, 1997a, Bertollo et al., 1997b; Lopes et al., 1998; Bertollo and Mestriner, 1998; Born and Bertollo, 2000). Specimens with a putative hybrid karyotype have not been found when distinct chromosomal forms (cytotypes) are sympatric (Bertollo et al., 2000). ...
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A substantial fraction of the eukaryotic genome consists of repetitive DNA sequences that include satellites, minisatellites, microsatellites, and transposable elements. Although extensively studied for the past three decades, the molecular forces that generate, propagate and maintain repetitive DNAs in the genomes are still discussed. To further understand the dynamics and the mechanisms of evolution of repetitive DNAs in vertebrate genome, we searched for repetitive sequences in the genome of the fish species Hoplias malabaricus. A satellite sequence, named 5SHindIII-DNA, which has a conspicuous similarity with 5S rRNA genes and spacers was identified. FISH experiments showed that the 5S rRNA bona fide gene repeats were clustered in the interstitial position of two chromosome pairs of H. malabaricus, while the satellite 5SHindIII-DNA sequences were clustered in the centromeric position in nine chromosome pairs of the species. The presence of the 5SHindIII-DNA sequences in the centromeres of several chromosomes indicates that this satellite family probably escaped from the selective pressure that maintains the structure and organization of the 5S rDNA repeats and become disperse into the genome. Although it is not feasible to explain how this sequence has been maintained in the centromeric regions, it is possible to hypothesize that it may be involved in some structural or functional role of the centromere organization.
... Although several karyotypes have been reported for the Hoplias malabaricus group (e.g. Bertollo et al., 1983;Dergam & Bertollo, 1990;Bertollo et al., 2000), only one karyotype has been described for specimens of the Hoplias lacerdae group collected in the upper rio Paraná basin (Bertollo et al., 1978). The diploid number cited by these authors, 2n = 50, is regarded herein as belonging to H. intermedius, as that species occurs in the upper rio Paraná basin. ...
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The taxonomy of the nominal species of giant trahiras Hoplias aimara (Valenciennes, 1846) and Hoplias macrophthalmus (Pellegrin, 1907), both described from Cayenne (French Guiana), was evaluated to determine whether they constitute distinct forms and to determine the geographic distribution of the recognized species. A total of 200 specimens were examined (30–624 mm standard length). Analysis of meristic and morphometric data resulted in the recognition of a single species. Study of the type-specimens revealed that both species names, H. aimara and H. macrophthalmus, refer to the same taxon. According to the Principle of Priority of the International Code of Zoological Nomenclature the name Hoplias aimara has precedence. This species is distinguished from congeners by the presence of a vertically-elongate dark spot on the median portion of the opercular membrane and by the absence of the accessory ectopterygoid. Hoplias aimara occurs in the drainages of Rio Tocantins, Rio Xingu, Rio Tapajós, Rio Jarí, and Rio Trombetas, in coastal drainages of the Guyanas, Suriname, and state of Amapá, Brazil. In the Río Orinoco basin, the species occurs only in the Río Caroní and rivers to the east of this drainage. Literature records of Hoplias aimara for the Rio Purus and upper Río Orinoco were based on misidentifications. This pattern of geographic distribution of Hoplias aimara in rivers of the Guyanas and Brazilian Shields also occurs in other Neotropical species of fishes.
... Although several karyotypes have been reported for the Hoplias malabaricus group (e.g. Bertollo et al., 1983;Dergam & Bertollo, 1990;Bertollo et al., 2000), only one karyotype has been described for specimens of the Hoplias lacerdae group collected in the upper rio Paraná basin (Bertollo et al., 1978). The diploid number cited by these authors, 2n = 50, is regarded herein as belonging to H. intermedius, as that species occurs in the upper rio Paraná basin. ...
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Hoplias lacerdae was originally described from the rio Ribeira de Iguape, Iporanga, São Paulo State. The Hoplias lacerdae group is defined as containing generally large trahiras with the medial margins of dentaries running parallel to each other and lacking teeth on the basihyal compared to the H. malabaricus group in which the medial margins of the dentaries converge towards the mandibular symphysis and which have teeth on the basihyal. A taxonomic revision of the group based on meristic and morphometric data identified five distinct species: H. lacerdae distributed in the rio Ribeira de Iguape and rio Uruguai; H. intermedius from the rio São Francisco, upper rio Paraná basin, and rio Doce; H. brasiliensis from rivers of the Atlantic Coastal drainage from the rio Paraguaçu to the rio Jequitinhonha; H. australis new species, endemic to the rio Uruguai; and H. curupira new species present in northern South America, including the rios Negro, Trombetas, Tapajós, Xingu, Tocantins and Capim in the Amazon basin, upper rio Orinoco near the rio Casiquiare (Venezuela), and coastal rivers of Guyana and Suriname. A lectotype for Hoplias intermedius and a neotype for H. brasiliensis are designated.
... Although Hoplias malabaricus has been considered as a single biological species in reference to its morphological traits, every sampled population shows a bimodal pattern of variation: they are either 2n=42 or 2n=40 with slight modifications. Several cytogenetic studies indicate that Hoplias malabaricus represents a species complex, with seven well characterized karyomorphs (or karyotypic variants, also known as cytotypes) nominated with letters A to G, which differ with regards to their diploid numbers, chromosome morphology and the presence of sex chromosome systems (Bertollo et al. 1983, 1997a, 1997b, Dergam and Bertollo 1990, Bertollo and Mestriner 1998. Some karyomorphs as A, C and F have a wide geographic distribution throughout South America, whereas others are either endemic or restricted to specific drainages in Brazil , Da Rosa et al. 2014. ...
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Citation: Grassi DJ, Swarça AC, Dergam JA, Pastori MC, Fenocchio AS (2017) Cytogenetic characterization of Hoplias malabaricus (Bloch, 1794) from the Ctalamochita River (Córdoba, Argentina): first evidence for southernmost populations of this species complex and comments on its biogeography. Comparative Cytogenetics 11(1): 15–28. https:// Abstract Hoplias malabaricus (Bloch, 1794), a predatory freshwater fish with a wide distribution throughout South America, represents a species complex with seven well characterized karyomorphs at the cytogenetic level. Although this species has been extensively studied in several Brazilian basins, data are still scarce for hydro-graphic systems from other South American countries. This study aims to characterize cytogenetically the Hoplias malabaricus populations from the Argentinean Central Region, close to the southernmost distribution of this species complex. A total of 32 specimens from the Ctalamochita River, a tributary of Lower Paraná Basin located in the province of Córdoba, were analyzed using cytogenetic techniques (Giemsa staining, C-and Ag-NOR banding and fluorescent in situ hybridization with 18S rDNA). All the specimens showed diploid number 2n=42, chromosomic formula 22m + 20sm and absence of sexual chromo-A peer-reviewed open-access journal Diego Javier Grassi et al. / Comparative Cytogenetics 11(1): 15–28 (2017) 16 somes. Thus, the analyzed populations belong to the karyomorph named A. These populations showed a remarkable degree of divergence in their cytogenetic traits such as karyotypic formula, C-banding, NORs and 18S rDNA patterns for Hoplias malabaricus from other populations bearing the same karyomorph in the Middle and Upper Paraná Basin. These findings are consistent with molecular data from a recent study (where specimens collected in the present work were included), which indicate a closer phylogenetic relationship of Hoplias malabaricus populations from the Ctalamochita River with those from the Uruguay basin and the coastal regions of South Brazil than with populations from the Middle and Upper Paraná Basin. Overall, these pieces of evidence highlight the distinctive features of Hoplias malabaricus from the Ctalamochita River, and also reveal a complex history of dispersion of these populations. The present work is the first to provide cytogenetic information and include some phylogeographic aspects of Hoplias mala-baricus populations living in close proximity to the southernmost extreme of its distribution area. Therefore , this study expands significantly upon the previously known geographical coverage for karyomorph A and contributes to a better understanding of the karyotypic diversification within this species complex.
... In general, H. malabaricus present C-positive heterochromatin at the centromeric regions of all chromosomes and over telomeres in a few pairs. The pattern of C-bands distribution detected in the samples of the present study was similar to that reported for other populations of H. malabaricus (Dergam & Bertollo, 1990;Haaf et al., 1993;Bertollo et al., 1997), with the predominant occurrence on the centromeres of all chromosomes. The more conspicuous heterochromatic bands that appear to occur in the population from Itapicuru River basin may indicate a certain degree of genetic differentiation between both populations analyzed, probably due to mechanisms of heterochromatin dispersal (Schweizer & Loidl, 1987) or by multiple replication and accumulation steps (John, 1988). ...
Article
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The species Hoplias malabaricus is a predator fish found in nearly all cis-Andean basins. From a cytogenetic point of view, this species comprises, at least, seven differentiated karyomorphs. Several localities have been formerly analyzed in Brazil, however, some regions, such as Bahia State, remain underrepresented. Recently, the Brazilian Environment Ministry classified both Itapicuru and Contas river basins (entirely located within Bahia territory) as priority conservation areas, whose biodiversity status lacks enough information. Therefore, the goal of the present work was to characterize, cytogenetically, populations of H. malabaricus from both basins, by using conventional staining, Ag-NOR and C-banding techniques. All specimens presented a diploid number of 2n = 40 with metacentric/submetacentric chromosomes, without differences between sexes, thereby representing the so-called "karyomorph F". The first metacentric pair presented a remarkably larger size in relation to the other pairs. The NORs were multiple, comprising the terminal region on long arms of two chromosomal pairs in both populations. However, the C-banding pattern was somewhat distinguishable between samples. Although sharing heterochromatic blocks at centromeric region of all chromosomes, the population from Itapicuru River basin appeared to have some more conspicuous blocks than those observed in the population from Contas River basin. The similar karyotype observed in both populations suggests a common geological history between them. The present results represent an advance in the knowledge about the cytogenetic pattern of H. malabaricus populations from poorly studied basins.
... The more practical reason for studying sex determination and sex differentiation in fish is to obtain potential benefits of monosex production, with higher growth rate, superior Heteromorphic Rainbow trout [184] XX XO Heteromorphic Triacanthus brevirostris [185] ZW ZZ Homomorphic Tilapia mariae [41] Heteromorphic Leporinus sp . [186] ZW ZO Heteromorphic Colisa lalius [187] X 1 X 1 X 2 X 2 X 1 X 2 Y H eteromorphic Lutjanus quinquelineatus [188] XX XY 1 Y 2 Heteromorphic Hoplias malabaricus [189] XX X 1 X 2 Y H eteromorphic Hoplias malabaricus [190] Z W 1 W 2 ZZ Heteromorphic Apareiodon affinis [191] Multifactorial system XX, XW, WY XY, YY Homomorphic Platyfish [192] Minor sex factors Poly-factorial system N/A N/A N/A zebrafish [193] Environmentdependent sex Environmental differences plus genetic factors ...
Chapter
Understanding sex determining (SD) mechanisms and related concepts in a wide range of fish species is critical for sex control and large‐scale monosex production in aquaculture, in which monosex culture is superior to mixed‐sex culture. Establishment of phenotypic sex is triggered by SD factor(s), modulated by complex molecular networks, and influenced by environmental conditions, steroid hormones, and endocrine disrupting chemicals. Temperature‐dependent sex determination (TSD) presents in fish, and the feature has been applied to monosex production in several fish species, since many downstream aspects of TSD are shared with genotypic sex determination (GSD). Although SD genes have been identified in some fish, the complex molecular networks involved in sex differentiation remain unclear. Large‐scale monosex production could be achieved in the third generation with sex‐linked markers (SLMs), and in the fourth generation with no available SLMs in fish with a XY or ZW SD mode. There is a great potential for producing large‐scale breeding systems for females in much less time if gynogenesis and sex reversal of XX‐females are combined. In addition, atypical genotypes (YY and WW) have the potential to serve as a biological tools to control invasive species in natural waters. In this chapter, we briefly review the concepts and practices of sex control in fish and aquaculture, based on the achievements during the past two decades.
... H. malabaricus with cytotype C (2n = 40) in the haplogroups of the hydrological basins in Northeastern Brazil have been characterised as another cytotype, designated F (which is like cytotype C (2n = 40), but without differentiation between males and females). Its distinctive feature is the presence of a large metacentric pair, the number 1 in the karyotype, which constitutes also the largest chromosome known for H. malabaricus (Dergam and Bertollo 1990;Jacobina et al. 2009). Indeed, this suggests that the macrostructural karyotypic classification of that taxon is not adequate for the recognition of monophyletic groups, but rather represents a homoplastic character. ...
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We assessed the presence of independent evolving lineages of the trahira, Hoplias malabaricus, one of the few freshwater fish species having wide distribution in the Neotropics which is the region with the highest global diversity of freshwater fish. To achieve that goal, 58 mitochondrial sequences of cytochrome c oxidase subunit I (COI; DNA barcoding) were generated from collected samples and 85 obtained from public databases, which were analyzed in comparison to chromosomal and geological data. The magnitude of genetic diversity found among different sampling sites was greater than 2%. Molecular species delimitation methods indicated the existence of a least four distinct lineages. The recognised cytotypes did not form monophyletic groups, suggesting that the karyotypic macrostructure could be a homoplastic character. The haplotype relationships suggested secondary contacts between the ecoregions of Northern and Northeastern Brazil that were shaped by coastal routes between adjacent watersheds during the Pleistocene epoch and probable exchanges of their ichthyofaunas. Our results indicated that multiple factors have driven the diversification of H. malabaricus, from ancient geological events linked to the reactivation of tectonic faults to more recent occurrences related to eustatic changes in ocean levels. Ultimately, the magnitude of its genetic diversity suggests the necessity of revising its taxonomic status.
... Meristic and morphometric data of specimens greatly overlap throughout the distribution range of the species (e.g., Bifi, 2013), and there is a large number of nominal species currently considered junior synonyms (e.g., Oyakawa, 2003), many of which without known type material. In addition, numerous cytogenetic studies have suggested that H. malabaricus represents a species complex (e.g., Bertollo et al., 1986;Dergam & Bertollo, 1990;Bertollo et al., 1997;2000;Born & Bertollo, 2001;Cioffi et al., 2009aCioffi et al., , 2009bRosa et al., 2009;Santos et al., 2009;Blanco et al., 2010;2011;Cioffi & Bertollo, 2010;Cioffi et al., 2011aCioffi et al., , 2011bCioffi et al., , 2011cCioffi et al., , 2011dMarques et al., 2013). ...
Article
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The Hoplias malabaricus species group represents one of the most complexes taxonomical problems in the systematics of Neotropical fishes, including specimens widely distributed in most drainages of South America and part of Central America with great variation or overlap of putative diagnostic characters. The large number of nominal species, many of which without known type material, renders the problem more complicated. Currently, at least three nominal species can be included in the Hoplias malabaricus species group based on the form of the medial margins of dentaries and presence of tooth plates on the tongue: Hoplias malabaricus, H. teres, and H. microlepis, the latter representing the only exclusively trans-Andean known species of the genus. We present herein a taxonomic study of Hoplias microlepis based on examination of syntypes and recently collected specimens, including a redescription of the species. Hoplias microlepis occurs in the Pacific drainages of Panama and Southwestern Costa Rica, in addition to the río Guayas basin in Ecuador and the region near its mouth (río Tumbes, Northwestern Peru). Records of the species on the Atlantic coast of Panama are restricted to the Canal Zone, suggesting dispersal through the Panama Canal. We also designate lectotype and paralectotypes.
... Other chromosome markers of Boulengerella were tentatively used for a comparative analysis with erythrinid and some lebiasinid species, which represent the only Erythrinoidea taxa having available chromosome data until now. In this regard, the single NORs of the ctenoluciids contrast with the multiple NORs found in most erythrinids [Dergam and Bertollo, 1990;Oliveira et al., 1991;Bertollo et al., 1997;Cioffi et al., , 2011 and lebiasinids [Oliveira et al., 1991;Moraes et al., in preparation]. However, although multiple NORs are common in the erythrinids, with up to 8 sites in H. malabaricus and Erythrinus erythrinus , and 4-6 sites in Hoplerythrinus unitaeniatus , this is not a general rule in the Erythrinidae family, since species of the Hoplias lacerdae group have single NORs [Bertollo, 2007;Martinez et al., 2016;Oliveira et al., 2016]. ...
Article
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Ctenoluciidae is a Neotropical freshwater fish family whose representatives are known as bicudas. The genus Boulengerella contains 5 species, and 4 of them (B. cuvieri, B. lateristriga, B. lucius, and B. maculata) were cytogenetically analyzed in the present study by conventional and molecular procedures. All 4 species have a very similar karyotype, with 2n = 36 chromosomes (14 metacentrics + 16 submetacentrics + 6 subtelocentrics; FN = 72). However, the heterochromatin distribution pattern is species-specific. In all 4 species, the nucleolus organizer region is located in pair 18, as also confirmed by cytogenetic mapping of 18S rDNA. In turn, 5S rRNA genes are present in 2 chromosome pairs: in pair 1 of all 4 species, and in pair 10 of B. lateristriga, B. maculata, and B. cuvieri, but in pair 4 of B. lucius. The telomeric probe highlighted terminal regions in all chromosomes, as well as an interstitial centromeric sequence in pair 3 of the 3 first-mentioned species. Notably, a conspicuous heteromorphic secondary constriction in chromosomes 18 was found only in the males of the 3 species, rendering one of the homologs much larger than the other one. This feature, associated with a large 18S rDNA block and accumulation of telomeric sequences, suggests the presence of an XX/XY sex chromosome system in the analyzed Boulengerella species.
... The distribution of heterochromatin in all the karyomorphs of the H. malabaricus complex has often been described in the terminal and pericentromeric region of some pairs of chromosomes (Dergam and Bertollo 1990, Haff et al. 1993, Bertollo et al. 1997a, 1997b, Vicari et al. 2005, Blanco et al. 2010, and was also observed in the population of the present study. However, a small variation in the amount and location of heterochromatin can be observed between the various allopatric populations already studied (i.e., Blanco et al. 2010). ...
Article
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Erythrinidae include Neotropical teleost fish that are widely distributed in South America. Hoplias Gill, 1903 include two large groups: H. malabaricus Bloch, 1794 and H. lacerdae Miranda Ribeiro, 1908. Hoplias malabaricus is characterized by remarkable karyotype diversity, with some karyomorphs widely distributed geographically while others are more restricted to certain river basins. Cytogenetic analyzes were performed in a population of Hoplias malabaricus from the Wildlife Refuge of Campos de Palmas, the Iguaçu River basin. The specimens showed diploid number of 42 chromosomes (24m+18sm) without differentiated sex chromosomes system. The impregnation by silver nitrate showed multiple AgNORs. Seven pairs (4, 7, 10, 13, 16, 20 and 21) carrying 18S rDNA were detected by FISH. Heterochromatin was verified in the centromeric and pericentromeric region of most chromosomes and the terminal region of some pairs. FISH with 5S rDNA probes showed two chromosome pairs carrying these sites in the interstitial region (8 and 14). The data obtained in this study are similar to those found for two other populations of H. malabaricus already studied in the basin of the Iguaçu River, confirming the hypothesis that this species is natural, not having been introduced, as well as having an intrinsic characteristic, such as the largest number of sites of 18S rDNA.
... It is important to note that the cannibalism of Hoplias spp. was not evaluated in this study. As Hoplias consists of a complex of species (Dergam & Bertollo, 1990;Vicari et al., 2005;Blanco et al., 2010), with at least three recognized morphotypes with different cytotypes in the upper Paraná River floodplain region (Pazza & Júlio-Jr, 2003;Graça & Pavanelli, 2007), the predation of Hoplias spp. by other Hoplias spp. ...
Article
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Floodplain river systems are extremely dynamic environments, where alternating dry and flooded periods affect the availability of food resources for fish. For piscivores, during drought years, a decreased availability of prey is expected, resulting in diets dominated by fewer items, narrower trophic niches with high dietary overlap. During floods, habitats become more similar, and, combined with increased connectivity, provide a wider diversity of prey to piscivores, decreasing dietary overlap and presenting wider trophic niches. This study aimed to evaluate the potential impacts of long periods of flooding on the trophic ecology of nine piscivorous fish in the upper Paraná River basin. In drought years, diets were dominated by small characids, presenting narrower niches with higher dietary overlap. The opposite situation was observed during wet years, with different species responses, likely due to species-specific feeding strategies. High niche overlap was observed between native and non-native species, suggesting competition. The inclusion of non-native species in the native piscivorous diet is a concerning fact, as its causes and possible impacts are still unknown. In conclusion, long flooding pulses affect the diets of piscivorous fish in different ways by either increasing or decreasing niche breadth and overlap according to species-specific characteristics.
... Pericentromeric and terminal heterochromatic bands have frequently been found in the group H. malabaricus (Dergam & Bertollo, 1990;Haaf et al., 1993;Bertollo et al., 1997 a, b;Vicari et al., 2005;Blanco et al., 2009), as also seen in the populations of the present study. However, some degree of variation in the amount and location of heterochromatin were also evident. ...
Article
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Three populations of the group Hoplias malabaricus from the hydrographic basins of the São Francisco, Araguaia/Tocantins and Xingu Rivers in Brazil were analyzed using classic cytogenetic methods (Giemsa staining, C-banding and Ag-NORs) and molecular methods (fluorescent in situ hybridization with 18S rDNA, 5S rDNA and 5SHindIII satellite DNA probes). The chromosome markers allowed the characterization of these populations as belonging to karyomorph A and the detection of inter-population divergences. These differences likely stem from different evolutionary histories resulting from geographic isolation between populations associated to the dispersive mode of these organisms, reinforcing genetic diversity in the group Hoplias malabaricus.
... Although usually considered as a single biological species, the taxonomy of Hoplias malabaricus is poorly understood. Growing evidence has pointed to the karyotypic diversity of H. malabaricus, showing interpopulational differences in the diploid number and chromosome morphology, as well as in sex chromosome systems Moreira-Filho, 1978, 1983;Dergam and Bertollo, 1990;Fontes, 1997a, Bertollo et al., 1997b;Lopes et al., 1998;Bertollo and Mestriner, 1998;Born and Bertollo, 2000). Specimens with a putative hybrid karyotype have not been found when distinct chromosomal forms (cytotypes) are sympatric . ...
... Similar to that observed in this study, the distribution of heterochromatin, with blocks in the terminal regions of the chromosomes and at the centromere and surrounding regions, as well as its position relative to ribosomal sites, is frequent in H. malabaricus. 9,28,33,34,[43][44][45] In this study, the ribosomal genes were preferentially located in the terminal region of the chromosomes, which is heterochromatic or flanked by heterochromatin. This location might explain the substantial variability of the mapped ribosomal sites because telomeric and heterochromatic regions are more permissive to the exchange of genetic material between chromosomes because of its proximity within the interphase nucleus. ...
Article
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Hoplias malabaricus comprises seven karyomorphs (A-G) and evolutionary units have been described in some of them. In this study, the karyotypic composition and genomic organization of individual H. malabaricus from Central Amazon are described and to verify whether they can be classified according to known karyomorphs. Individuals from the Ducke Reserve have 2n = 42 chromosomes, similar to karyomorph A. Individuals from Catalão Lake and Marchantaria Island exhibit 2n = 40 chromosomes, similar to karyomorph C. Regarding the constitutive heterochromatin, individuals from all locations present centromeric/pericentromeric blocks, in addition to some bitelomeric and interstitial markings. The number of chromosomes with nucleolar organizer region, 5S rDNA and 18S rDNA sites varied among the different locations. The Rex 3 element has a compartmentalized distribution at the terminal and centromeric regions of most chromosomes, with subtle differences among populations. Fluorescence in situ hybridization performed with a telomeric probe allowed the detection of these regions only at the terminal ends of the chromosomes. Thus, only the chromosomal macrostructure (karyomorphs A-G) is not sufficient to establish evolutionary units within the H. malabaricus group, considering differences in the genome organization that are found among their populations. Such differences in the genomic organization could be mainly caused by the sedentary habits of this species.
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The chromosomes of specimens from four Hoplias malabaricus populations from headwaters of adjacent river basins at Ponta Grossa, southern Brazil, were investigated using differential staining techniques (C-banding, AgNO3 and CMA3) and fluorescent in situ hybridization (FISH) with an 18S rDNA probe. The diploid chromosome number in representatives of all four populations was invariably 2n = 42, with karyotypes composed of 12 pairs of metacentrics and 9 pairs of submetacentrics, without heteromorphic sex chromosomes. This kind of karyotype represents cytotype A in regard to cytotypes identified previously in H. malabaricus, exhibiting however, at the same time, some differences in the distribution of constitutive heterochromatin segments and in the locations of nucleolus organizer regions (NORs). The apparent karyotype similarity strongly suggests a close kinship among the studied populations, but the small differences detected in the examined chromosomal markers indicate some evolutionary divergence due to gene flow restriction among them.
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A general survey of the occurrence of morphologically differentiated sex chromosomes in the neotropical freshwater fishes is presented. The total number of 32 occurrences involving simple XX-XY and ZZ-ZW, and multiple X1X2Y, XY1Y2 and ZW1W2 sex chromosome systems is described, with comments on the aspects of sex chromosome evolution in this fish fauna. The occurrence of different sex chromosome systems in related species of the same genus, or in different populations of the same nominal species, involving male and sometimes female heterogamety, and differences in the molecular composition of sex-linked heterochromatin, are considered as indicative of the early stage of sex chromosomes evolution in fish.
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The available chromosomal data on Hoplias malabaricus make possible the identification of three major karyotypic forms in this fish group, all of them bearing 2n = 42 chromosomes, and named as Cytotypes A, B and E in previous studies. While Cytotype A and B share a general macrokaryotypic feature, Cytotype E is well differentiated concerning the morphology and size of some chromosome pairs. On the other hand, Cytotype B presents an exclusive XX/XY sex chromosome system. Six allopatric populations, belonging to Cytotype A, were subjected to cytogenetic analysis in the present study. Despite their basic karyotypic similarity, some differences in the chromosome formulae, as well as in the heterochromatin and Ag-NORs locations, were observed among populations indicating that they no more correspond to a unit, at least in the cytogenetical level.
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Cytogenetic studies were carried out in the fish, Hoplias malabaricus, from the Parque Florestal do Rio Doce (Brazil). This population is characterized by 2n = 42 chromosomes for both males and females and an XX/XY sex chromosome system, confirmed through several banding methods. Females show 24 metacentric, 16 submetacentric and 2 subtelocentric chromosomes. Males show 24 metacentric, 17 submetacentric and 1 subtelocentric chromosomes. While the X chromosome is easily recognized (the only subtelocentric element), the Y chromosome is somewhat difficult to identify but appears to correspond to the smallest submetacentric in the male karyotype. In-situ hybridization with an 18S rDNA probe showed 10 well-labeled chromosomes, including the X chromosome. The 5S rDNA is interstitially located in a single metacentric pair independent of the 18S rDNA sites. The NOR on the X chromosome is always active and occurs adjacent to a heterochromatic distal segment on the long arm. Variations in size of the NORs and/or heterochromatic segment correspond to a polymorphic size condition observed in the X chromosome. The present results confirm the XX/XY sex chromosome system in the population analyzed as well as a new cytotype in the Hoplias malabaricus group.
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Cytogenetic analyses were performed on Hoplias malabaricus (Bloch, 1794) from the Taquari River, Parana River drainage, revealing two sympatric karyomorphs. One karyomorph was characterized by 2n = 40 m/sm and 2n = 39 m/sm chromosomes for females and males, respectively, and an X 1X 1X 2X 2/X 1X 2Y sex chromosome system. In the second karyomorph, specimens showed 2n = 42 m/sm chromosomes, without sex-related heteromorphism. Both karyomorphs were characterized by a distribution of heterochromatin in the pericentromeric and telomeric regions. In addition to the differences in the diploid numbers and the sex chromosomes, the GC-rich sites and the nucleolar organizer regions also showed clear differences between the karyomorphs. Coupled with the occurrence of unique chromosomal features within each karyomorph, the fact that hybrids have not been identified in the sampled population provides additional support of the existence of a species complex in H. malabaricus.
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The chromosomes of the primitive South American teleost fish Hoplias malabaricus have been analyzed by classical cytogenetic (C-, AgNOR-, Hoechst 33258-, and Q-banding) techniques. A highly repetitive DNA family has been cloned and sequenced. It is a tandemly repeated sequence of about 355 bp, yielding an overall base pair composition of 67% AT with long runs of > 50% As and 70% Ts. Analysis of sequence variation has allowed the further categorization of Hoplias satellite DNA into two evolutionary related subfamilies A and B, distinguishable by characteristic insertions and deletions within this 355-bp monomer. Subfamily A satellite is found (in diverged form) at the centromeres of most H. malabaricus chromosomes. Sequence variants are clustered on specific chromosomal subsets. Subfamily B satellite is highly specific for the paracentromeric heterochromatin on one particular chromosome pair by fluorescence in situ hybridization. These results indicate that the Hoplias satellite DNA family has evolved in a concerted manner predominantly via recombination events involving homologous, rather than non-homologous chromosome regions. The clones isolated here may be useful for the molecular, genetic, and cytological analysis of the genus Hoplias.
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Parodon hilarii, a neotropical fish species of the family Parodontidae, presents a well-differentiated ZZ/ZW system, with a W chromosome being the largest in the complement and mostly heterochromatic. A review of the sex chromosome of neotropical fish is presented and some aspects of their differentiation are discussed, with emphasis on the family Parodontidae.
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Cytogenetic investigations were carried out on two populations of Astyanax scabripinnis (Pisces, Characidae, Tetragonopterinae) allopatrically distributed at different altitudes in a stream called Piracuama (Paraíba do Sul Basin, Brazil). Specimens collected at 1800m altitude revealed a diploid number of 2n=50 and a karyotype consisting of 6M+24SM+6ST+14A, with a fundamental number of FN=86. In one of the individuals from this location, we detected the presence of a B-macrochromosome (approximately 8.5% of the haploid complement) similar to those of the first pair in the complement and C positive banding in all extention. The specimens collected from the population located at 780m in the same stream also presented 2n=50, but a karyotype consisting of 4M+10SM+6ST+30A characterized by FN=70. The number of chromosomes bearing nucleolar organizer regions (NORs) also proved to be a differentiation factor at the level of cytogenetic analysis between the specimens of the two populations studied. The distribution of few heterochromatin spots in the chromosomes was a characteristic of both populations. A brief review about the chromosome information currently available about the A. scabripinnis complex is also presented and the possible evolutionary mechanisms involved in the great diversity and speciation of this complex are discussed.
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A great deal of information is known regarding the process of sex differentiation in fish, and the mechanisms involved in primary sex determination are now beginning to be defined. A range of gonadal differentiation types have been described for fish, including gonochoristic species possessing purely ovarian or testicular tissues, as well as hermaphroditic species that can initially mature either as males (protandrous) or females (protogynous). Sex determination in fish is a very flexible process with respect to evolutionary patterns observed among genera and families, and within individuals is subject to modification by external factors. These influences can affect the fate of both somatic and germ cells within the primordial gonad, and include the action of genetic, environmental (e.g. temperature), behavioural, and physiological factors. Exogenous sex steroids administered at the time of sex determination can strongly influence the course of sex differentiation in fish, suggesting that they play a critical role in assignment of gonad determination as well as subsequent differentiation. Detailed information is available from fish systems describing the production of sex steroids, as well as the enzymes involved in steroid production. Both estradiol and the maturation hormone 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-DP) are produced by a two-step process involving different cell layers in the gonad, and have effects on the differentiation of gonadal and nongonadal tissues. Gonadal development and differentiation in some fish is also controlled by hormones from the pituitary gland (gonadotropins) that are regulated by release hormones (GnRH) and other neuroendocrine and gonadal factors. Genetic determination of sex in fish can involve monogenic or polygenic systems, with factors located on the autosomes or on sex chromosomes. In the latter case, both male (XY) and female (ZW) heterogametic systems have been described, as well as many subtle variations on these themes. Sex chromosomes are found in approximately 10% of fish species examined, and sex-linked phenotypic traits, and protein and molecular genetic markers have been identified in several fish systems. Some species of fish reproduce gynogenetically, producing all-female populations. Several gene families known to be involved in sex determination in other vertebrates have recently been shown to be similarly involved in fish, suggesting conservation of sex determination pathways. The lability of sex-determination systems in fish makes some species sensitive to environmental pollutants capable of mimicking or disrupting sex hormone actions. Such observations provide important insight into potential impacts from endocrine disruptors, and can provide useful monitoring tools for impacts on aquatic environments.
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Karyotypic analyses were performed in fishes from the genus Hoplias (H. malabaricus and H. lacerdae groups) from the São Francisco River basin (Brazil), in an impacted region by a river transposition which altered the local ecology and fish fauna. The karyotypes were investigated using chromosomal markers obtained from classic and molecular cytogenetics (Giemsa, CMA3 and DAPI staining, C-banding, Ag-NORs, and FISH with 18S rDNA, 5S rDNA and 5SHindIII satellite DNA probes). Two karyotypic forms were found for the H. malabaricus group—karyomorph F, corresponding to the native form from the São Francisco River basin, and karyomorph A, corresponding to the invading form from the Upper Paraná River basin. Specimens from the H. lacerdae group exhibited striking chromosome differences in relation to the H. malabaricus group, thereby enabling good cytotaxonomic characterization and inferences regarding the karyotype evolution of these groups.
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This study assessed the coexistence of three species of thraira present in the Upper Parana River floodplain, using population structure as an investigation tool. The species were designated as: Hoplias sp. 1, introduced after the construction of the Itaipu reservoir, and Hoplias sp. 2 and Hoplias sp. 3, native species that have been identified as Hoplias aff. malabaricus. We tested the hypothesis that those species in fact differ from each other in respect of population abundance, sex ratio, relative frequency of adults and juveniles, length structure and weight-length relationship. Additionally, possible effects of the flood pulse on the first four of these parameters were investigated. Samples were collected quarterly from March 2006 to December 2007 from nine collection sites on the floodplain. Hoplias sp. 1 presented a greater balance of sex ratio and length structures over the seasons, as well as a higher allometric coefficient. The population attributes of Hoplias sp. 2 and Hoplias sp. 3 showed a high responsiveness to hydrological seasonality, indicating that these species exploit available resources in a conspicuous flood period with greater efficiency. These differences, beyond reflecting possible mechanisms that allow closely related species to coexist, indicate the importance of understanding the life strategies adopted by each species which, as part of a complex system, are considered key elements of the aquatic community structure in the region, providing important information for habitat management and biodiversity conservation.
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Abstract Hoplias malabaricus is a species widely distributed throughout Brazil. Cytogenetic studies indicate the occurrence of extensive chromosomal rearrangements in population differentiation and speciation of the group that demonstrated an independent origin of sex chromosome systems. Seven karyomorphs were characterized for the species and are located in specific river basins, while others are distributed throughout several different basins. However, there are few studies linking the geographical distribution of H. malabaricus karyomorphs to the Brazilian hydrographic basins. This article provides new chromosomal information on five populations of H. malabaricus collected in a South Atlantic basin. The samples were analyzed by conventional and molecular cytogenetic techniques. Two karyomorphs, A (2n=42 m/sm) and C (2n=40 m/sm), were detected, and remarkable differences in the distribution of heterochromatin and GC-rich blocks were observed in the karyomorphs. A review of existing data is presented here, where we observe that dispersion is associated with the genesis of the South and Central America river basins. Coastal drainages represent an ancestral biogeographical component for many groups of fish, representing older basins, such as the basins of the Eastern Atlantic and San Francisco river, suggesting that existing karyomorphs found in these basins may represent a basal karyotype (karyomorph F) within H. malabaricus. The current cytogenetic data, including this article, for different karyomorphs of H. malabaricus in conjunction with the geological history of the continent allow us to determine that the ancestral group is most likely karyomorph F.
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La presencia de Hoplias malabaricus en la hidrografía ecuatoriana es muy extensa dada la riqueza hídrica del país, la cual posee las condiciones físicas y climáticas requeridas por esta especie. Pese a estar catalogada por la Unión Internacional para la Conservación de la Naturaleza como una especie de preocupación menor, la “Tararira” es uno de los peces carnívoros de río más importantes de la región, por lo cual conocer su distribución hidrogeográfica mediante el uso de los programas Maxent y DivaGis, es el primer paso para el desarrollo de prácticas de conservación eficientes. Para esto, se utilizaron 97 registros compilados de la especie y 19 variables bioclimáticas dadas por Bioclim. Los resultados arrojados por el modelamiento indican que H. malabaricus, está distribuida en la mayoría de cuencas hidrográficas de Ecuador, principalmente en los ríos Pastaza y Bobonaza; en contraposición del modelamiento ejecutado, apunta que la distribución de H. malabaricus estaría en las cercanías a los ríos Coca, Napo y San Miguel, por ende, corresponden a áreas donde el nicho de la “Tararira” es ideal para realizar proyectos viables de conservación de la especie. Es recomendable ampliar estudios científicos que corroboren tanto la taxonomía como la distribución de la misma, ya que es una especie que genera confusión hasta la actualidad.
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