What determines whether an axolotl will grow up to be male or female?
Axolotls have genetic sex-determination - a locus on an axolotl chromosome determines whether an axolotl is male or female.
In salamanders, the sex determining mechanism is referred to as ZZ/ZW and the heterogametic sex is female. The sex-determining locus has been located in the axolotl genome but the underlying gene has not been identified. Our studies suggest that it is on the chromosome currently referred to as linkage group 9.
To learn more:
Smith JJ, Voss SR. 2009. Amphibian sex determination: segregation and linkage analysis using members of the tiger salamander species complex (Ambystoma mexicanum and A. tigrinum). Heredity 102:542-548.