The Asian box turtle genus Cuora currently comprises 13 species with a wide distribution in Southeast Asia, including China and the islands of Indonesia and Philippines. The populations of these species are rapidly declining due to human pressure, including pollution, habitat loss, and harvesting for food consumption. Notably, the IUCN Red List identifies almost all species of the genus Cuora as Endangered (EN) or Critically Endangered (CR). In this study, we explore the karyotypes of 10 Cuora species with conventional (Giemsa staining, C-banding, karyogram reconstruction) and molecular cytogenetic methods (in situ hybridization with probes for rDNA loci and telomeric repeats). Our study reveals a diploid chromosome number of 2n = 52 chromosomes in all studied species, with karyotypes of similar chromosomal morphology. In all examined species, rDNA loci are detected at a single medium-sized chromosome pair and the telomeric repeats are restricted to the expected terminal position across all chromosomes. In contrast to a previous report, sex chromosomes are neither detected in Cuoragalbinifrons nor in any other species. Therefore, we assume that these turtles have either environmental sex determination or genotypic sex determination with poorly differentiated sex chromosomes. The conservation of genome organization could explain the numerous observed cases of interspecific hybridization both within the genus Cuora and across geoemydid turtles.

• Klíčová slova
• C-banding, Cuora, FISH, Geoemydidae, evolution, heterochromatin, karyotype, microsatellites, rDNA, telomeres,
• MeSH
• cytogenetické vyšetření * MeSH
• fylogeneze MeSH
• hybridizace in situ fluorescenční MeSH
• karyotyp MeSH
• mikrosatelitní repetice MeSH
• molekulární evoluce MeSH
• pruhování chromozomů MeSH
• ribozomální DNA genetika   MeSH
• taxonomické DNA čárové kódování MeSH
• telomery MeSH
• želvy klasifikace   genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ribozomální DNA MeSH

Turtles demonstrate variability in sex determination ranging from environmental sex determination (ESD) to highly differentiated sex chromosomes. However, the evolutionary dynamics of sex determining systems in this group is not well known. Differentiated ZZ/ZW sex chromosomes were identified in two species of the softshell turtles (Trionychidae) from the subfamily Trionychinae and Z-specific genes were identified in a single species. We tested Z-specificity of a subset of these genes by quantitative PCR comparing copy gene numbers in male and female genomes in 10 species covering the phylogenetic diversity of trionychids. We demonstrated that differentiated ZZ/ZW sex chromosomes are conserved across the whole family and that they were already present in the common ancestor of the extant trionychids. As the sister lineage, Carettochelys insculpta, possess ESD, we can date the origin of the sex chromosomes in trionychids between 200 Mya (split of Trionychidae and Carettochelyidae) and 120 Mya (basal splitting of the recent trionychids). The results support the evolutionary stability of differentiated sex chromosomes in some lineages of ectothermic vertebrates. Moreover, our approach determining sex-linkage of protein coding genes can be used as a reliable technique of molecular sexing across trionychids useful for effective breeding strategy in conservation projects of endangered species.

• MeSH
• biologická evoluce MeSH
• dějiny starověku MeSH
• fylogeneze * MeSH
• interakce genů a prostředí MeSH
• mapování chromozomů MeSH
• pohlavní chromozomy chemie   MeSH
• procesy určující pohlaví * MeSH
• RNA ribozomální genetika   dějiny   MeSH
• skořápky zvířat anatomie a histologie   MeSH
• želvy anatomie a histologie   klasifikace   genetika   MeSH
• zvířata MeSH
• Check Tag
• dějiny starověku MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• historické články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• RNA ribozomální MeSH

Using nearly range-wide sampling, we analyze up to 1848 bp of mitochondrial DNA of 183 helmeted terrapins and identify a minimum of 12 deeply divergent species-level clades. Uncorrected p distances of these clades equal or clearly exceed those between the currently recognized species of Pelusios, the genus most closely related to Pelomedusa. We correlate genetic discontinuities of Pelomedusa with data on morphology and endoparasites and describe six new Pelomedusa species. Moreover, we restrict the name Pelomedusa subrufa (Bonnaterre, 1789) to one genetic lineage and resurrect three further species from its synonymy, namely P. galeata (Schoepff, 1792), P. gehafie (Rüppell, 1835), and P. olivacea (Schweigger, 1812). In addition to these ten Pelomedusa species, we identify two further clades from Cameroon and Sudan with similar levels of genetic divergence that remain unnamed candidate species. We also note that some problematical terrapins from South Africa and Somalia may represent two additional candidate species. Some of the Pelomedusa species are morphologically distinctive, whilst others can only be identified by molecular markers and are therefore morphologically cryptic taxa.

• MeSH
• biodiverzita * MeSH
• fylogeneze MeSH
• mitochondriální DNA * MeSH
• želvy anatomie a histologie   klasifikace   genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Madagaskar MeSH
• Střední východ MeSH
• subsaharská Afrika MeSH
• Názvy látek
• mitochondriální DNA * MeSH