SEXING BIRDS USING RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) MARKERS

We used random amplified polymorphic DNA (RAPD) markers to sex birds f rom small tissue (usually blood) samples. Arbitrarily chosen 10-mer PC R primers were screened with DNA from known-sex individuals for the pr oduction of a bright female-specific band. Suitable primers were found for seven bird species after screening about 30 primers (range 2-63), and no primer was found for three other species after screening about 50 primers for each species. Investigations into the reliability of R APD markers for sexing great tits Parus major and oystercatchers Haema topus ostralegus show that: (i) when PCR reaction conditions for great tit DNA are varied, either the presence of the female-specific band c orrectly predicts the individual's sex or no DNA amplification occurs; (ii) the female-specific band in great tits can be sequenced,and subs equently amplified using specific PCR primers; (iii) null alleles of t he female-specific fragment occur at an estimated frequency of 0% (n = 241 females) in great tits and 0.6% (n > 290 females) in oystercatche rs; (iv) the female-specific fragment in great tits occurs in individu als from a wide geographical range encompassing two subspecies; and (v ) the relative intensity of bands in great tit RAPD banding profiles i s consistent across individual birds and scorers. The RAPD primers tha t we have identified are generally species specific, and the consequen t time cost of screening for primers is the chief disadvantage of usin g RAPD markers to sex birds. However, with large sample sizes this dis advantage is outweighed by the relative technical simplicity and low c ost of the technique.