Author contributions
EN and VB designed the study, performed all statistical analyses, and drafted the manuscript. Adult frogs were captured and morphologically sexed, and DNA samples were taken from them by VV, BÜ, and VB. Eggs were collected by VB, BÜ, NU, VV and EN. Froglets in the laboratory were raised by VB, ZM, NU, EN and VV. Dissection and phenotypic sexing was performed by NU and VV, and histological samples were prepared and analysed by KKL. DNA extractions were performed by EN. Putatively sex-linked sequences were identified by DLJ, out of which loci were chosen by EN and VB for further analyses based on genome data provided by DLJ. PCR primers were designed, PCR conditions were optimized and PCR-based sexing was performed by EN, while HRM primers were designed and HRM conditions were optimized by OIH and ZG, and HRM-based sexing was performed by ZG. Genotype analyses were performed by EN, and geoinformatics analyses were performed by NU. All authors proofread the manuscript, EN, VB, DLJ and BÜ revised the first draft, and all authors gave final approval for publication.