A nondestructive method for obtaining maternal DNA from avian eggshells and its application to embryonic viability determination in herring gulls (Larus argentatus)

Many avian studies, aimed at collecting samples for genetic analysis, rely upon invasive procedures involving the capture and handling of parents and their offspring. Our goal was to develop a nondestructive method for sampling maternal DNA that would not require blood collection from the mother. Herein, we describe a method for isolating genomic DNA from eggshell powder, obtained by filing the outer shell of an avian egg. Comparison of microsatellite profiles, obtained from genomic DNA found within eggshell matrices and their corresponding parents, verified the presence of maternal DNA in the eggshell matrix in 100% of the herring gull nests assessed (n= 11). In addition, the microsatellite profiles of eggshell DNA were identical among eggs from the same clutch. The ability to rapidly obtain a DNA sample from an avian eggshell in a noninvasive manner could aid in a wide range of genetic sampling studies, and in this study, we provide one potential application of this finding: assessing the fertilization status of nonviable herring gull (Larus argentatus) eggs from the Laurentian Great Lakes. Detection of fertilization was successful as the microsatellite profiles of eggshell powder (maternal only) and the fertilized embryonic contents of those eggs did not match. Ideally, the application of such an approach will help to discriminate unfertilized eggs from embryos aborted early in development and provide insights into avian reproductive health.