A PCR-based method for sex identification in Hippopotamus amphibius

Abstract

Identification of the sex of aquatic mammals such as the hippopotamus (Hippopotamus amphibius) is difficult in the field. We have developed a PCR-based method for sex identification in the hippopotamus. This method amplifies a short fragment of the ZFX and ZFY genes from the X and Y chromosomes. The PCR products are then digested with the restriction endonuclease HaeIII. The method was verified using tissue samples taken from six captive animals in zoos. We then collected 54 tissue samples from free-ranging hippos in Kruger National Park, South Africa, using a biopsy dart and cross-bow. The PCR method correctly identified the sex of all individuals for whom the sex was known (either zoo animals, or those exhibiting clear behaviours or morphologies in the field). Field identification of the sex of other individuals was prone to error (6 of 22 misidentified, 27 %).