A new karyotype and a molecular phylogeny of Lebiasinidae (Teleostei: Characiformes) shed light on the chromosomal evolution of the family

Abstract

Cytogenetic and molecular data play critical roles in understanding the evolution of non-model species. Together, they offer an integrated approach that enables a robust understanding of genetic diversity, population structure, and phylogenetic relationships within groups. Studies on Lebiasinidae fish are challenging, mainly because of their small size. However, with advancements in collection methods and chromosomal preparation, the number of studies on the family has increased significantly. Here we filled an important gap by describing, for the first time, the karyotype of a Copella species (C. callolepis), showing 2n = 36 with a predominance of acrocentric chromosomes and multiple 5S and 18S rDNA sites. Furthermore, by coupling an SNP-based phylogenetic tree, a NeighborNet network, and previous cytogenetic data, we achieved a comprehensive understanding of the genetic relationships among the sampled Lebiasina, Nannostomus, Pyrrhulina, Copella, and Copeina species. In light of these new data and previous morphology-based phylogenetic analyses, we reevaluated the chromosomal evolution patterns of Lebiasinidae and suggested the most plausible evolutionary pathways. Our data support that extensive chromosome rearrangements occurred in Lebiasinidae fishes, with independent events of fusions and fissions.

Keywords:
C-banding; DArTSeq; Neotropical; Ribosomal DNA; Single nucleotide polymorphism