Cytogenetic analysis of Phyllomedusa distincta Lutz, 1950 (2n=2x=26), P. tetraploidea Pombal and Haddad, 1992 (2n=4x=52), and their natural triploid hybrids (2n=3x=39) (Anura, Hylidae, Phyllomedusinae)

Author(s)

Gruber, Simone Lilian ^[1] ; Zampieri Silva, Ana Paula ^[1] ; Baptista Haddad, Celio Fernando ^[2] ; Kasahara, Sanae ^[1]

Affiliation

^[1] Univ Estadual Paulista, Inst Biociencias, Dept Biol, UNESP, BR-13506900 Rio Claro, SP - Brazil

^[2] Univ Estadual Paulista, Inst Biociencias, Dept Zool, UNESP, BR-13506900 Rio Claro, SP - Brazil

• Document type: Journal article
• Source: BMC GENETICS; v. 14, AUG 30 2013.
• Web of Science Citations: 11

Abstract

Background: Natural polyploidy has played an important role during the speciation and evolution of vertebrates, including anurans, with more than 55 described cases. The species of the Phyllomedusa burmeisteri group are mostly characterized by having 26 chromosomes, but a karyotype with 52 chromosomes was described in P. tetraploidea. This species was found in sintopy with P. distincta in two localities of Sao Paulo State (Brazil), where triploid animals also occur, as consequence of natural hybridisation. We analyse the chromosomes of P. distincta, P. tetraploidea, and their triploid hybrids, to enlighten the origin of polyploidy and to obtain some evidence on diploidisation of tetraploid karyotype. Results: Phyllomedusa distincta was 2n = 2x = 26, whereas P. tetraploidea was 2n = 4x = 52, and the hybrid individuals was 2n = 3x = 39. In meiotic phases, bivalents were observed in the diploid males, whereas both bivalents and tetravalents were observed in the tetraploid males. Univalents, bivalents or trivalents; metaphase II cells carrying variable number of chromosomes; and spermatids were detected in the testis preparations of the triploid males, indicating that the triploids were not completely sterile. In natural and experimental conditions, the triploids cross with the parental species, producing abnormal egg clutches and tadpoles with malformations. The embryos and tadpoles exhibited intraindividual karyotype variability and all of the metaphases contained abnormal constitutions. Multiple NORs, detected by Ag-impregnation and FISH with an rDNA probe, were observed on chromosome 1 in the three karyotypic forms; and, additionally, on chromosome 9 in the diploids, mostly on chromosome 8 in the tetraploids, and on both chromosome 8 and 9 in the triploids. Nevertheless, NOR-bearing chromosome 9 was detected in the tetraploids, and chromosome 9 carried active or inactive NORs in the triploids. C-banding, base-specific fluorochrome stainings with CMA(3) and DAPI, FISH with a telomeric probe, and BrdU incorporation in DNA showed nearly equivalent patterns in the karyotypes of P. distincta, P. tetraploidea, and the triploid hybrids. Conclusions: All the used cytogenetic techniques have provided strong evidence that the process of diploidisation, an essential step for stabilising the selective advantages produced by polyploidisation, is under way in distinct quartets of the tetraploid karyotype. (AU)

• FAPESP's process: 13/07358-8 - Comparative cytogenetic analysis in diploid and polyploid Phyllomedusa species from the group P. burmeisteri (Phyllomedusinae, Hylidae, Anura)
• Grantee: Simone Lilian Gruber
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 08/50928-1 - Speciation of frogs in high-altitude environments
• Grantee: Célio Fernando Baptista Haddad
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 06/06634-8 - Molecular phylogeny and phylogeography of Leptodactylus (Amphibia, Anura, Leptodactylidae)
• Grantee: Ana Paula Zampieri Silva de Pietri
• Support Opportunities: Scholarships in Brazil - Post-Doctoral