Chromosome banding in three species of Hypsiboas (Hylidae, Hylinae), with special reference to a new case of B-chromosome in anuran frogs and to the reduction of the diploid number of 2n = 24 to 2n = 22 in the genus

Abstract

The chromosomes of hylids Hypsiboas albopunctatus, H. raniceps, and H. crepitans from Brazil were analyzed with standard and differential staining techniques. The former species presented 2n = 22 and 2n = 23 karyotypes, the odd diploid number is due to the presence of an extra element interpreted as B chromosome. Although morphologically very similar to the small-sized chromosomes of the A complement, the B was promptly recognized, even under standard staining, on the basis of some characteristics that are usually attributed to this particular class of chromosomes. The two other species have 2n = 24, which is the chromosome number usually found in the species of Hypsiboas karyotyped so far. This means that 2n = 22 is a deviant diploid number, resulted from a structural rearrangement, altering the chromosome number of 2n = 24 to 2n = 22. Based on new chromosome data, some possibilities were evaluated for the origin of B chromosome in Hypsiboas albopunctatus, as well as the karyotypic evolution in the genus, leading to the reduction in the diploid number of 2n = 24 to 2n = 22.

Dynamics of chromosomal evolution in the genus Hypsiboas (Anura: Hylidae)

“…On the other hand, NORs in species and populations of Hypsiboas are variable, although most species presented single NORs located interstitially on long arms of mediumsized to small chromosomes (pairs 7, 10, and 11; present study; Ananias et al, 2004;Gruber et al, 2006;Nunes and Fagundes, 2008). Besides interspecific variation, 2 populations of H. crepitans (present study; Gruber et al, 2006) also differed in relation to the NOR-bearing pair.…”

“…The karyotype consisting of 24 chromosomes or lower diploid values present in derived anuran families such as Dendrobatidae, Hylidae, Leptodactylidae, and Ranidae have been thought to have evolved through numerical reduction from a putative ancestor with 2n = 26 (Bogart, 1973), as Dynamics of chromosomal evolution in the genus Hypsiboas corroborated by the phylogeny proposed by Faivovich et al (2005). According to Gruber et al (2006), 2 mechanisms could account for the reduction in the diploid number of H. albopunctatus: tandem fusions or translocations between the smallest chromosomes that also likely resulted in the differential NOR position. These authors have also argued that the occurrence of a supernumerary chromosome reported in this species could be indicative of the former presence of 24 chromosomes in H. albopunctatus.…”

“…After the chromosomal measurements were standardized, 8 karyotype groups could be defined, many of which were shared by distinct species (Table 2 and Figure 3). (Nunes and Fagundes, 2008); C. H. albopunctatus (Gruber et al, 2006); D. H. crepitans (Gruber et al, 2006); E. H. crepitans (present study); F. H. raniceps (Gruber et al, 2006); G. H. bischoffi (Raber et al, 2004); H. H. guentheri (Raber et al, 2004); I. H. marginatus ; J. H. pardalis (Nunes and Fagundes, 2008); K. H. semiguttatus ; L. H. sp aff semiguttatus ; M. H. semilineatus (Nunes and Fagundes, 2008); N. H. semilineatus (present study); O. H. pombali (present study); P. H. faber (Carvalho et al, 2009); Q. H. faber (Nunes and Fagundes, 2008); R. H. polytaenius (Nunes and Fagundes, 2008); S. H. atlanticus (present study). Table 1.…”

“…Within Hypsiboas, cytogenetic data have been shown for only 16% of the species, most of which have been derived based on conventional karyotype descriptions, and thus, some inferences about their chromosomal evolution that need to be determined using banding techniques are missing (Raber et al, 2004;Ananias et al, 2004;Gruber et al, 2006;Nunes and Fagundes, 2008;Carvalho et al, 2009). …”

Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

“…In the present work our efforts were the use of replication banding after 5-bromodeoxiuridine treatment, an useful approach to identify homeologous chromosomes (Kasahara et al 2003, Silva et al 2004, Gruber et al 2007, Gazoni et al 2012, Gruber et al 2013). This methodology is very effective for comparative analyses in fishes, amphibians, and reptiles due to the difficulty in producing classical Q, G, and R banding patterns in the chromosomes of the ectothermic vertebrates (Sumner 2003).…”