Chromosomes of Asian cyprinid fishes: Variable karyotype patterns and evolutionary trends in the genus Osteochilus (Cyprinidae, Labeoninae, “Osteochilini”)

Abstract

The Cyprinidae family is a highly diversified but demonstrably monophyletic lineage of cypriniform fishes. Among them, the genus Osteochilus contains 35 recognized valid species distributed from India, throughout Myanmar, Laos, Thailand, Malaysia, Indonesian archipelago to southern China. In this study, karyotypes and other chromosomal characteristics of five Osteochilus species occurring in Thailand, namely O. lini, O. melanopleura, O. microcephalus, O. vittatus and O. waandersii were examined using conventional and molecular cytogenetic protocols. Our results showed they possessed diploid chromosome number (2n) invariably 2n = 50, but the ratio of uni-and bi-armed chromosomes was highly variable among their karyotypes, indicating extensive chromosomal rearrangements. Only one chromosome pair bearing 5S rDNA sites occurred in most species, except O. melanopleura, where two sites were detected. In contrast, only one chromosomal pair bearing 18S rDNA sites were observed among their karyotypes, but in different positions. These cytogenetic patterns indicated that the cytogenomic divergence patterns of these Osteochilus species were largely corresponding to the inferred phylogenetic tree. Similarly, different patterns of the distributions of rDNAs and microsatellites across genomes of examined species as well as their different karyotype structures indicated significant evolutionary differentiation of Osteochilus genomes.

Chromosomes of Asian Cyprinid Fishes: Genomic Differences in Conserved Karyotypes of ‘Poropuntiinae’ (Teleostei, Cyprinidae)

“…This chromosomal number is also seen in diploid members of other cyprinid lineages, in addition to diploid Acrossocheilinae and Labeoninae [ 2 , 3 , 54 ]. Indeed, 2n = 50 appears to be preserved in various cyprinid and cobitoid fish lineages [ 35 ].…”

Novel Gene Rearrangement in the Mitochondrial Genome of Three Garra and Insights Into the Phylogenetic Relationships of Labeoninae

“…First, the clade1, genera Cirrhinus, and Labeo show a sister relationship, both of them were once classified in the genus Labeonini ( Yang et al, 2012 ). Then, the clade2, including Henicorhynchus , Crossocheilus , Thynnichthys , Osteochilus , and Labiobarbus , which belonged to “ Osteochilini ” ( Saenjundaeng et al, 2020 ). The clade3 aggregates all mitochondrial genes with rearrangements in the genus Garra .…”

A Fish of Multiple Faces, Which Show Us Enigmatic and Incredible Phenomena in Nature: Biology and Cytogenetics of the Genus Carassius

“…Conventional banding techniques together with more advanced molecular cytogenetics (e.g., in situ hybridization) are widely utilized in many species and may determine a tempo of karyotype evolution focused on repetitive ribosomal DNA (rDNA) loci, microsatellite motifs, ratio of parental genomes within a hybrid genome etc. [ 58 , 59 , 60 ]. The fluorescent in situ hybridization (FISH) method has a diverse utilization in a study of evolutionary processes due to many modifications focused on various types of targeted nucleotide sequences used as probes in various animal species [ 61 , 62 , 63 ].…”