Work

Genome‐Wide Characterization of Sex‐Linked Regions in the Sangzhi Horned Toad ( Boulenophrys sangzhiensis ) Reveals Complex Sex Determination Mechanisms

Year: 2026

Type: article

Abstract: ABSTRACT Sex chromosomes in amphibians exhibit substantial variability and often remain largely homomorphic, providing a powerful system for studying sex determination. The Sangzhi horned toad ( Boulenophrys sangzhiensis ) is an ideal model, but limited genomic resources have hindered insights into sex determination mechanisms. Here, we assembled a 2.8 Gb chromosome‐level genome of B . sangzhiensis generated using PacBio HiFi and Hi‐C data, achieving a Contig N50 of 30 Mb and identifying 21,775 protein‐coding genes. Genome‐wide analyses of coverage, F ST , SNP density, and linkage disequilibrium identified two putative sex‐linked regions on chromosome 2 and 6, showing sex‐specific coverage and strong genetic differentiation. Within these sex‐linked regions, we identified a Y‐specific sequence and several candidate sex‐determining genes, including Hsd11b2 , Nlrp14 , and zinc finger genes. Our findings suggest that sex determination in B . sangzhiensis involves a complex, possibly polymorphic mechanism, with multiple Y haplotypes segregating within populations. Additionally, the sex‐linked regions exhibit accumulation of repetitive sequences, multi‐copy genes, and chromosomal rearrangements, which may contribute to the evolution of sex chromosomes. This chromosome‐level genome provides a valuable resource for understanding the dynamic evolution of sex‐determining mechanisms in amphibians.

Source: Molecular Ecology Resources

DOI: 10.1111/1755-0998.70136