Comparative cytogenetics of tree frogs of the Dendropsophus marmoratus (Laurenti, 1768) group: conserved karyotypes and interstitial telomeric sequences

Abstract

The diploid number 2n = 30 is a presumed synapomorphy of Dendropsophus Fitzinger, 1843, although a noticeable variation in the number of biarmed/telocentric chromosomes is observed in this genus. Such a variation suggests that several chromosomal rearrangements took place after the evolutionary origin of the hypothetical ancestral 30-chromosome karyotype; however, the inferred rearrangements remain unknown. Distinct numbers of telocentric chromosomes are found in the two most cytogenetically studied species groups of Dendropsophus. In contrast, all three species of the Dendropsophus marmoratus (Laurenti, 1768) group that are already karyotyped presented five pairs of telocentric chromosomes. In this study, we analyzed cytogenetically three additional species of this group to investigate if the number of telocentric chromosomes in this group is not as variable as in other Dendropsophus groups. We described the karyotypes of Dendropsophus seniculus (Cope, 1868), Dendropsophus soaresi (Caramaschi & Jim, 1983) and Dendropsophus novaisi (Bokermann, 1968) based on Giemsa staining, C-banding, silver impregnation and in situ hybridization with telomeric probes. Dendropsophus seniculus, Dendropsophus soaresi and Dendropsophus novaisi presented five pairs of telocentric chromosomes, as did the remaining species of the group previously karyotyped. Though the species of this group show a high degree of karyotypic similarity, Dendropsophus soaresi was unique in presenting large blocks of het-ITSs (heterochromatic internal telomeric sequences) in the majority of the centromeres. Although the ITSs have been interpreted as evidence of ancestral chromosomal fusions and inversions, the het-ITSs detected in the karyotype of Dendropsophus soaresi could not be explained as direct remnants of ancestral chromosomal rearrangements because no evidence of chromosomal changes emerged from the comparison of the karyotypes of all of the species of the Dendropsophus marmoratus group.

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae)

“…Similarly, in Hylini the three species of Acris have x = 11 [ 35 , 62 , 63 ]. In Dendropsophini, the diploid number of x = 12 is also common, despite the derived condition of x = 15 observed in all the 33 studied species of Dendropsophus ([ 25 , 30 , 63 – 65 ], and references therein). Other variations within Dendropsophini correspond to Pseudis cardosoi (x = 14), Scarthyla goinorum , Scinax constrictus (x = 11), and Sphaenorynchus carneus (x = 13) [ 25 , 66 , 67 ].…”

“…We optimized the basic chromosome number and the position of NORs of all the karyotypes described for Hylinae (see [ 22 ] for a review; [ 24 – 25 , 27 – 30 , 38 ], and references therein; see S1 Table for chromosome information in Cophomantini) on the phylogenetic hypothesis of Duellman et al [ 7 ], as it is based on a reanalysis of most available hylid GenBank sequences, and is the latest and most inclusive phylogenetic hypothesis for the family. For the optimization of the basic number we considered the states of x = 9, 10, 11, 12, and 13 and for the chromosome location of NORs we considered NORs in pairs 1, 2, 4, 6, 8, 11, and 12.…”

“…The data on hylid cytogenetics, with about 340 karyotyped species, makes it one of the most studied groups among Anura ([ 22 ], and references therein; [ 23 – 30 ]). Cytogenetic data are available for 230 spp.…”

Heterochromatin variation and LINE-1 distribution in Artibeus (Chiroptera, Phyllostomidae) from Central Amazon, Brazil

“…1f, g ). There are two potential explanations for the presence of telomeric sequences in interstitial position (ITS): (i) these sequences might be telomere motifs reallocated from the terminal region of a chromosome to another chromosome or chromosome position; and (ii) the ITS presence on the centromere derives from reorganization of repetitive sequences (satellite DNA) composing these regions, which could also indicate the presence of centromeric hotspots of recombination during Artibeus karyotype evolution ( Nanda and Schmid 1994 , Multani et al 2001 , Metcalfe et al 2007 , Faria et al 2009 , Kasahara 2009 , Silva et al 2016 , Teixeira et al 2016 ). The karyotypic evolution of Artibeus is considered extremely conservative, however the formation of the ancestral karyotype of the subfamily Stenodermatinae required extreme reshuffling ( Baker and Bickham 1980 , Pieczarka et al 2013 ).…”

Repetitive DNA Mapping in Five Genera of Tree Frogs (Amphibia: Anura) from the Atlantic Forest: New Highlights on Genomic Organization in Hylidae

“…In addition to the diploid number, the NORs and 18S sequences have conserved characteristics and are found at the same loci in species within these genera or within species groups (see references in online suppl. material) [10][11][12][13][14][15][16][17][18][19].…”