Abstract
We present the first cytogenetic data for Lebiasina bimaculata and L. melanoguttata with the aim of (1) investigating evolutionary events within Lebiasina and their relationships with other Lebiasinidae genera and (2) checking the evolutionary relationships between Lebiasinidae and Ctenoluciidae. Both species have a diploid number 2n = 36 with similar karyotypes and microsatellite distribution patterns but present contrasting C-positive heterochromatin and CMA3+ banding patterns. The remarkable interstitial series of C-positive heterochromatin occurring in L. melanoguttata is absent in L. bimaculata. Accordingly, L. bimaculata shows the ribosomal DNA sites as the only GC-rich (CMA3+) regions, while L. melanoguttata shows evidence of a clear intercalated CMA3+ banding pattern. In addition, the multiple 5S and 18S rDNA sites in L. melanogutatta contrast with single sites present in L. bimaculata. Comparative genomic hybridization (CGH) experiments also revealed a high level of genomic differentiation between both species. A polymorphic state of a conspicuous C-positive, CMA3+, and (CGG)n band was found only to occur in L. bimaculata females, and its possible relationship with a nascent sex chromosome system is discussed. Whole chromosome painting (WCP) and CGH experiments indicate that the Lebiasina species examined and Boulengerella maculata share similar chromosomal sequences, thus supporting the relatedness between them and the evolutionary relationships between the Lebiasinidae and Ctenoluciidae families.
Highlights
Lebiasinidae (Characiformes) are small freshwater fishes comprising approximately 74 valid species widely distributed throughout South and Central America, from Costa Rica to Argentina [1,2].Two subfamilies and seven genera are currently recognized: Lebiasininae (Lebiasina, Piabucina, and Derhamia) and Pyrrhulininae (Pyrrhulina, Nannostomus, Copeina, and Copella) [2]
The C-positive heterochromatin was located in the centromeric and telomeric regions of several chromosomes in both species, but L. melanoguttata displayed an exclusive set of conspicuous interstitial C-bands (Figure 1b,e and Figure S1)
This study provides the first chromosomal data for Lebiasina species, allowing for the investigation of the karyoevolutionary process between two Lebiasina species and their relationships, as well as their relationship with other Lebiasinidae species and with other fish families
Summary
Lebiasinidae (Characiformes) are small freshwater fishes comprising approximately 74 valid species widely distributed throughout South and Central America, from Costa Rica to Argentina [1,2].Two subfamilies and seven genera are currently recognized: Lebiasininae (Lebiasina, Piabucina, and Derhamia) and Pyrrhulininae (Pyrrhulina, Nannostomus, Copeina, and Copella) [2]. Lebiasinidae (Characiformes) are small freshwater fishes comprising approximately 74 valid species widely distributed throughout South and Central America, from Costa Rica to Argentina [1,2]. The phylogenetic position of Lebiasinidae with respect to other Characiformes groups is not well defined. In this sense, it has been proposed as being closely related to different Characiformes families, such as Ctenoluciidae, Erythrinidae, and Hepsetidae [5,6,7]. Recent phylogenetic analyses based on molecular data have repeatedly considered Lebiasinidae as closely related to Ctenoluciidae [8,9,10]
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