Chromosome evolution in dendropsophini (Amphibia, Anura, Hylinae).

Area of Science:

• Amphibian genetics
• Comparative genomics
• Evolutionary biology

Background:

• The tribe Dendropsophini, part of the Hylidae family, is the most species-rich group with 234 recognized species.
• Cytogenetic data within Dendropsophini is limited, yet chromosome number and morphology are vital for systematic studies.

Purpose of the Study:

• To characterize the karyotypes of Xenohyla, Scarthyla, and Sphaenorhynchus genera using diverse cytogenetic techniques.
• To provide novel cytogenetic information for Dendropsophus and Lysapsus genera.
• To analyze karyotype diversity and its implications for the systematic understanding of Dendropsophini.

Main Methods:

• Standard cytogenetic techniques.
• Molecular cytogenetic methods, including interstitial telomeric sequences.
• Analysis of nucleolar organizer regions (NORs) and C-banding patterns.

Main Results:

• Significant karyotype diversity was observed across Dendropsophini, with diploid chromosome numbers ranging from 2n=22 to 2n=30.
• Specific diploid numbers were identified for various genera: 2n=22 (S. goinorum), 2n=24 (Lysapsus, Scinax, Xenohyla, Sphaenorhynchus, Pseudis), 2n=26 (S. carneus), 2n=28 (P. cardosoi), and 2n=30 (Dendropsophus).
• Interstitial telomeric sequences indicated a chromosome fusion event leading to a diploid number reduction from 24 to 22 in Scarthyla. The 2n=30 karyotype in Xenohyla truncata supports its status as a synapomorphy for Dendropsophus.

Conclusions:

• Karyotype diversity is substantial within Dendropsophini, offering valuable cytological markers for evolutionary studies.
• NOR positions and C-banding patterns in specific genera are informative for phylogenetic analyses.
• The study establishes a foundation for future research into the cytogenetic evolution and systematics of Dendropsophini frogs.