Comparative cytogenetic analysis of some species of the Dendropsophus microcephalus group (Anura, Hylidae) in the light of phylogenetic inferences

Abstract

BackgroundDendropsophus is a monophyletic anuran genus with a diploid number of 30 chromosomes as an important synapomorphy. However, the internal phylogenetic relationships of this genus are poorly understood. Interestingly, an intriguing interspecific variation in the telocentric chromosome number has been useful in species identification. To address certain uncertainties related to one of the species groups of Dendropsophus, the D. microcephalus group, we carried out a cytogenetic analysis combined with phylogenetic inferences based on mitochondrial sequences, which aimed to aid in the analysis of chromosomal characters. Populations of Dendropsophus nanus, Dendropsophus walfordi, Dendropsophus sanborni, Dendropsophus jimi and Dendropsophus elianeae, ranging from the extreme south to the north of Brazil, were cytogenetically compared. A mitochondrial region of the ribosomal 12S gene from these populations, as well as from 30 other species of Dendropsophus, was used for the phylogenetic inferences. Phylogenetic relationships were inferred using maximum parsimony and Bayesian analyses.ResultsThe species D. nanus and D. walfordi exhibited identical karyotypes (2n = 30; FN = 52), with four pairs of telocentric chromosomes and a NOR located on metacentric chromosome pair 13. In all of the phylogenetic hypotheses, the paraphyly of D. nanus and D. walfordi was inferred. D. sanborni from Botucatu-SP and Torres-RS showed the same karyotype as D. jimi, with 5 pairs of telocentric chromosomes (2n = 30; FN = 50) and a terminal NOR in the long arm of the telocentric chromosome pair 12. Despite their karyotypic similarity, these species were not found to compose a monophyletic group. Finally, the phylogenetic and cytogenetic analyses did not cluster the specimens of D. elianeae according to their geographical occurrence or recognized morphotypes.ConclusionsWe suggest that a taxonomic revision of the taxa D. nanus and D. walfordi is quite necessary. We also observe that the number of telocentric chromosomes is useful to distinguish among valid species in some cases, although it is unchanged in species that are not necessarily closely related phylogenetically. Therefore, inferences based on this chromosomal character must be made with caution; a proper evolutionary analysis of the karyotypic variation in Dendropsophus depends on further characterization of the telocentric chromosomes found in this group.

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

“…Samples of genomic DNA were obtained from Dendropsophus seniculus (ZUEC 17225), D. soaresi (ZUEC 16867) and D. novaisi (ZUEC 17858) following the procedure reported by Medeiros et al (2013). A fragment of approximately 1300 bp of the 16S ribosomal RNA gene was PCR-amplified using the primers 12L13(L) (Feller and Hedges 1998) and 16Sbr(H) (Palumbi et al 1991).…”

“…Although all of the Dendropsophus species karyotyped to date show 2n = 30 (see review in Catroli and Kasahara 2009, Medeiros et al 2013, Suárez et al 2013, Oliveira et al 2016), a noticeable variation in the number of biarmed/telocentric chromosomes is observed among them, suggesting that several chromosomal rearrangements took place after the evolutionary origin of the hypothetical ancestral 30-chromosome karyotype. Karyotypes with only biarmed chromosomes [as in D. minutus (Peters, 1872) (Gruber et al 2005) and D. leali (Bokermann, 1964) (Bogart 1973)] and karyotypes with up to five pairs of telocentric/subtelocentric chromosomes [as in D. labialis (Peters, 1863) (Bogart 1973), D. sanborni (Schmidt, 1944) and D. jimi (Napoli & Caramaschi, 1999) (Medeiros et al 2013)] may be observed.…”

“…Some adult and larval morphological synapomorphies of this species group may be recognized (Faivovich et al 2005); however, its cladistic proximity with other Dendropsophus species groups as well as the internal phylogenetic relationships of this group remain unclear (Faivovich et al 2005;Pyron and Wiens 2011, Fouquet et al 2011, Medeiros et al 2013. To date, up to three of the eight species of the D. marmoratus group have been included in phylogenetic analysis (Fouquet et al 2011).…”

“…Karyotypes with only biarmed chromosomes [as in D. minutus (Peters, 1872) (Gruber et al 2005) and D. leali (Bokermann, 1964) (Bogart 1973)] and karyotypes with up to five pairs of telocentric/subtelocentric chromosomes [as in D. labialis (Peters, 1863) (Bogart 1973), D. sanborni (Schmidt, 1944) and D. jimi (Napoli & Caramaschi, 1999) (Medeiros et al 2013)] may be observed. However, the chromosomes and events involved in these rearrangements also remain undiscovered because most Dendropsophus species karyotypes are not yet described, and few chromosomal markers are available for the known karyotypes, preventing reliable hypotheses of chromosome homeology.…”

“…Of the nine species groups recognized in Dendropsophus (for a review of the Dendropsophus groups, see Faivovich et al 2005), the D. microcephalus (Cope, 1886) group is the most species-rich (currently with 40 species-Frost 2016) and the most studied cytogenetically (17 species karyotyped-review by Catroli and Kasahara 2009, Medeiros et al 2013, Oliveira et al 2016. It is noteworthy that karyotypes without any telocentric chromosome (in D. leali-Bogart 1973) (Bogart 1973, Kaiser et al 1996, Gruber et al 2005, which currently has 11 species (see Frost 2016) and is the second most cytogenetically studied species group of Dendropsophus (four of the named species are karyotyped).…”