Sample extraction and SNP sequencing data for: Identification of sex-linked SNP markers in wild populations of monomorphic birds

Single-nucleotide polymorphism (SNP) analyses are a powerful tool for
population genetics, pedigree reconstruction and phenotypic trait mapping.
However, the untapped potential of SNP markers to discriminate the sex of
individuals in species with reduced sexual dimorphism or of individuals
during immature stages remains a largely unexplored avenue. Here, we
develop a novel protocol for molecular sexing of birds based on the
detection of unique Z- and W-linked SNP markers. Our method is based on
the identification of two unique loci, one in each sexual chromosome.
Individuals are considered males when they show no calls for the W-linked
SNP and are heterozygotic or homozygotic for the Z-linked SNP, while
females show both Z- and W-linked SNP calls. We validated the method in
the Jackdaw (Corvus monedula). The reduced sexual dimorphism in this
species makes it difficult to sex individuals in the wild. We assessed the
reliability of the method using 36 individuals of known sex and found that
their sex was correctly assigned in 100% of cases. The sex-linked markers
also proved to be widely applicable to discriminate males and females from
a sample of 927 genotyped individuals of different maturity stages with an
accuracy of 99.5%. Given that SNP markers are increasingly used in
quantitative genetic analyses of wild populations, the approach we propose
has a great potential to be integrated into broader genetic research
programmes without the need for additional sexing techniques.