Amphibian sex determination: Segregation and linkage analysis using members of the tiger salamander species complex (Ambystoma mexicanum and A. t. tigrinum)

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23 Scopus citations


Little is known about the genetic basis of sex determination in vertebrates though considerable progress has been made in recent years. In this study, segregation analysis and linkage mapping were performed to localize an amphibian sex-determining locus (ambysex) in the tiger salamander (Ambystoma) genome. Segregation of sex phenotypes (male and female) among the second generation individuals of interspecific crosses (Ambystoma mexicanum × Ambystoma tigrinum tigrinum) was consistent with Mendelian expectations, although a slight female bias was observed. Individuals from these same crosses were typed for single-nucleotide polymorphisms distributed throughout the genome to identify molecular markers for ambysex. A marker (E24C3) was identified approximately 5.9 cM from ambysex. Linkage of E24C3 to ambysex was independently validated in a second, intraspecific cross (A. mexicanum). Interestingly, ambysex locates to the tip of one of the larger linkage groups of the Ambystoma meiotic map. Considering that this location does not show reduced recombination, we speculate that the ambysex locus may have arisen quite recently, within the last few million years. Localization of ambysex sets the stage for gene identification and provides important tools for studying the effect of sex in laboratory and natural populations of this model amphibian system.

Original languageEnglish
Pages (from-to)542-548
Number of pages7
Issue number6
StatePublished - Jun 2009

Bibliographical note

Funding Information:
This study was supported by Grants R24-RR016344 and P20-RR016741 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NCRR or NIH. The National Science Foundation provided support through IBN-0242833. The Spinal Cord and Brain Injury Research Center at the United Kingdom and the NSF-supported Ambystoma Genetic Stock Center (DBI-0443496) provided resources and facilities. We also thank K Peichel for providing a critical review of the manuscript before submission.


  • Ambystoma
  • Evolution
  • Linkage map
  • Sex chromosome
  • Sex determination

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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