Molecular sexing of threatened Gyps vultures: an important strategy for conservation breeding and ecological studies

Prabhakar B Ghorpade,Nikita Prakash,Mandar Kulkarni,Vibhu Prakash,Anil K Sharma,Asit Das,Praveen K Gupta,Richard J Cuthbert,Mohini Saini

doi:10.1186/2193-1801-1-62

Abstract

During the last two decades populations of three resident species of Gyps vulture have declined dramatically and are now threatened with extinction in South Asia. Sex identification of vultures is of key importance for the purpose of conservation breeding as it is desirable to have an equal sex ratio in these monogamous species which are housed together in large colony aviaries. Because vultures are monomorphic, with no differences in external morphology or plumage colour between the sexes, other methods are required for sex identification. Molecular methods for sex identification in birds rely on allelic length or nucleotide sequence discrimination of the chromohelicase-DNA binding (CHD) gene located on male and female chromosomes ZZ and ZW, respectively. We characterized the partial sequences of CHD alleles from Gyps indicus, Gyps bengalensis, Gyps himalayensis and Aegypius monachus and analysed the applicability of five molecular methods of sex identification of 46 individual vultures including 26 known-sex G. bengalensis and G. indicus. The results revealed that W-specific PCR in combination with ZW-common PCR is a quick, accurate and simple method, and is ideal for sex identification of vultures. The method is also suitable to augment ecological studies for identifying sex of these endangered birds during necropsy examinations especially when gonads are not apparent, possibly due to regression during non-breeding seasons.

Highlights

Nine species of vultures in the family Accipitridae are found in India, three of which are endemic to South and South-East Asia (the Oriental white-backed vulture (Gyps bengalensis), long-billed (G. indicus) and slenderbilled vulture (G. tenuirostris) and are classified as Critically Endangered by the International Union for Conservation of Nature and Natural resources and are at high risk of extinction in the wild (IUCN, 2011)
These sequences were submitted to GenBank and accession numbers obtained were HQ236387, HQ236386 (G. indicus); HQ236388, HQ236385 (G. bengalensis); HQ236384, HQ236383 (G. himalayensis); HQ236382 (A. monachus)
The recognition sequence for BamHI was found on chromohelicase-DNA binding (CHD)-Z but was absent on the CHD-W sequence, whereas the RsaI restriction site was located at different positions in the CHD-Z and CHD-W sequences

Summary

Introduction

Nine species of vultures in the family Accipitridae are found in India, three of which are endemic to South and South-East Asia (the Oriental white-backed vulture (Gyps bengalensis), long-billed (G. indicus) and slenderbilled vulture (G. tenuirostris) and are classified as Critically Endangered by the International Union for Conservation of Nature and Natural resources and are at high risk of extinction in the wild (IUCN, 2011). Due to the massive scale of the population declines and the continued use of diclofenac, populations of the three Critically Endangered resident Gyps species are being bred in captivity in India, Nepal and Pakistan, with the aim that their progeny will be introduced back in to the wild after ensuring that the environment is safe and diclofenac free (MoEF 2006; Bowden 2009). As well as the key importance of identifying gender for conservation breeding programmes, knowledge of sex is important to complement forensic studies (An et al 2007) and investigations on evolution and ecology (Griffiths and Tiwari 1995; Costantini 2008; Fukui et al 2008)

Methods

Results

Conclusion