New Insights into the Biogeographic and Karyotypic Evolution ofHoplias Malabaricus

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.

DNA barcoding and phylogeography of the Hoplias malabaricus species complex

“…In the Amazon basin, five distinct karyomorphs (types A, C, E, F and G) were detected, including some highly dispersed through neighboring basins (types A, C and F) and others restricted (types E and G) 2 . Chromosomes were important to demonstrate intraspecific divergence of H. malabaricus populations and raise the hypothesis of a species complex hidden in this taxon 2 , 5 – 7 that was corroborated with molecular data 8 , 9 .…”

“…Cytogenetic data revealed karyotypic polymorphisms within H. malabaricus populations with chromosome morphology and diploid number variation (2n = 39–42), differentiated sex chromosome systems and other cytogenetic markers such as C-bands and Ag-NORs 2 , 5 , 6 . In the Amazon basin, five distinct karyomorphs (types A, C, E, F and G) were detected, including some highly dispersed through neighboring basins (types A, C and F) and others restricted (types E and G) 2 .…”

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

“…These features would favor a random fixation of chromosome rearrangements and, thus, certain degree of intra-karyomorph variation would be expected (Sites and Moritz 1987). Indeed, extensive karyotypic variation in karyomorph A has been reported for populations living in adjacent basins (Born and Bertollo 2001, Vicari et al 2005, Cioffi et al 2009, Blanco et al 2010, Da Rosa et al 2014). In this regards, populations from the Ctalamochita River seem to follow the rule since they display a unique character combination, diverging from other populations of the A karyomorph inhabiting the Paraná Basin and other hydrographical systems.…”

“…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, Born and Bertollo 2000, 2001). 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 (Bertollo et al 2000, Da Rosa et al 2014). In some cases, two and even more karyomorphs have been found coexisting in sympatric conditions without detection of hybrid forms (Lopes and Fenocchio 1994, Scavonne et al 1994, Lopes et al 1998, Lemos et al 2002, Pazza and Júlio 2003, Born and Bertollo 2006, Da Rosa et al 2009a, 2009b, 2010).…”

DNA Barcoding unveils cryptic lineages of Hoplias malabaricus from Northeastern Brazil

“…Some of the H. malabaricus cytotypes (for example 2n = 42A, 2n = 40C and 2n = 40F) are widely distributed in South America, while others are endemic to specific Brazilian river basins (Rosa et al, 2014). As the number of study areas has increased, the known cytogenetic diversity of H. malabaricus has also expanded progressively, to much higher levels than previously thought, with variation being found even within populations defined by a single cytotype (Vicari et al, 2005;Blanco et al, 2010).…”