Z and W sex chromosomes in the cane toad (Bufo marinus)

John Abramyan, Tariq Ezaz, Jenny Marshall Graves, Peter Koopman

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


The cane toad (Bufo marinus) is one of the most notorious animal pests encountered in Australia. Members of the genus Bufo historically have been regarded as having genotypic sex determination with male homogamety/female heterogamety. Nevertheless, as with many toads, karyotypic analyses of the cane toad have so far failed to identify heteromorphics sex chromosomes. In this study, we used comparative genomic hybridization, reverse fluorescence staining, C-banding, and morphometric analyses of chromosomes to characterize sex chromosome dimorphism in B. marinus. We found that females consistently had a length dimorphism associated with a nucleolus organizer region (NOR) on one of the chromosome 7 pair. A strong signal over the longer NOR in females, and the absence of a signal in males indicated sex-specific DNA sequences. All females were heterozygous and all males homozygous, indicating a ZZ/ZW sex chromosomal system. Our study confirms the existence of sex chromosomes in this species. The ability to reliably identify genotypic sex of cane toads will be of value in monitoring and control efforts in Australia and abroad.

Original languageEnglish
Pages (from-to)1015-1024
Number of pages10
JournalChromosome Research
Issue number8
Publication statusPublished - 2009


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