Improvement on molecular sex identification primers for Passeriform bird species

The primer pair sex1/sex2, which can be widely applied for sex identification in Galliform species, was used to determine the sex of 17 Passeriform species. As CHD-W fragments tended to be preferentially amplified, which may cause unnecessary misidentification in bird species with little difference between CHD-Z and CHD-W, we modified sex1 and sex2, obtaining sex1' and sex-mix respectively. Primer sets were then recombined to conduct sex identification. After testing several Passeriforme birds of known sex, we found that the primer pair sex1'/sex2 was better at limiting the preferential amplification of CHD-W fragments. As they are being frequently used in sex allocation study of Aegithalos concinnus and song learning research of Lonchura striata, we can expect more applications of this primer pair to further studies in Passeriformes.