Sex determining region Y (SRY) sequencing and non-invasive molecular sexing in three wild species: brown (Parahyaena brunnea) and spotted (Crocuta crocuta) hyenas and aardvark (Orycteropus afer)

Abstract

Non-invasive molecular sexing methods are useful in captive breeding programs and field studies; these methods enable sex identification without immobilisation or stressful handling of animals. We developed a method enabling fast and reliable sex identification in three species with limited external sexual dimorphism: the brown and spotted hyenas and the aardvark. We used the sex determining region Y (SRY) gene as the male-specific sequence and the c-myc gene, highly conserved among mammals, as the control sequence present in both sexes. Primers designed on the basis of the feline and human SRY gene enabled us to amplify and sequence the SRY gene fragment in hyenas and the aardvark. Subsequently, we used specific primers designed on the basis of the newly obtained sequences for sex determination in two brown hyenas, three spotted hyenas and six aardvarks. The sequences of the SRY gene fragments were further studied. Interspecies comparisons revealed high similarity in SRY sequences between both hyena species, as well as their relationships with the Felidae lineage. The aardvark, as the only species of the order Tubulidentata (Afrotheria), showed SRY gene similarities with Sirenia and Primates. Knowledge of phylogenetic relationships can be beneficial in genetic studies focused on species with limited sequence data.