Hoplias malabaricus is one of the most widespread freshwater fish in the Neotropics; all karyotyped populations exhibit diploid numbers ranging from 2n = 39 to 2n = 42, with variations that make up to seven karyomorphs, suggesting the existence of a species complex or paraspecies. In this study, we explored the diversity of H. malabaricus of the Magdalena River Basin using karyotypic analysis. Cytogenetic analyses were carried out on 32 specimens and six sample sites from the upper, middle, and lower Magdalena River, a trans-Andean basin in Colombia, using standard and molecular techniques and fluorescence in situ hybridization (FISH). The upper and middle Magdalena samples were 2n = 42 and showed unique fluorescence patterns, whereas the lower Magdalena samples had 2n = 40, generalized fluorescence patterns, and one specimen with a mosaic karyotype and heteromorphic chromosome pair. The genetic discontinuity along the Magdalena River fits the museum hypothesis, where the 2n = 42A predates the modern configuration of the Magdalena Basin in the Late Miocene, and the 2n = 40C karyomorph represents a more derived condition. Our results underline the complex biogeography of the trans-Andean region, where the Magdalena-Cauca Basin should be considered a freshwater fauna mosaic with divergent evolutionary affinities.

中文翻译：

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马格达莱纳河（哥伦比亚—南美洲北部）沿线的霍普利亚斯（Chariaciformes，Erythrinidae）的染色体多样性及其对新热带地区的意义

Hoplias malabaricus是新热带地区最广泛使用的淡水鱼之一。所有核型的种群都显示出二倍体数，范围从2 n  = 39到2 n  = 42，其变异组成多达7个核型，表明存在物种复合体或亚种。在这项研究中，我们使用核型分析探索了马格达莱纳河流域的斑节菌。使用标准和分子技术以及荧光原位杂交技术（FISH）对来自哥伦比亚跨安第斯盆地的马格达莱纳河上，中和下河的32个样本和6个样本点进行了细胞遗传学分析。玛格达莱纳的上层和中层样品均为2 n = 42并显示出独特的荧光模式，而较低的Magdalena样品则具有2 n  = 40，广义荧光模式，并且一个样本具有镶嵌核型和异型染色体对。沿着马格达莱纳河的遗传不连续性符合博物馆的假设，其中2 n  = 42A早于中新世中的马格达莱纳盆地的现代形态，而2 n  = 40C的核型代表了更为衍生的条件。我们的结果强调了跨安第斯地区的复杂生物地理，在这里，马格达莱纳-高加索盆地应被视为具有不同进化亲和力的淡水动物区系。