Molecular tools for species and sex identification in the mixed-species flocks of bean geese and white-fronted geese.

Genetic studies on protected species can be difficult, particularly when they form a mixed-species flock with other species. The bean goose (Anser fabalis), which is internationally recognized as a threatened species, was observed to form overwintering foraging flocks with white-fronted goose (Anser albifrons) at agricultural lands to feed on the grains in Korea. Non-invasive samples such as feces and feather that are readily available in their foraging ground can be useful for understanding the structure and composition of populations, but they often require specific experimental conditions due to small amount or low quality of DNA. In this study, we designed sets of primers that would allow efficient molecular identification of species and sex of individuals of bean geese and white-fronted geese. Species-specific primers (WFG-F/BG-F and G-R), developed from ND2 region of mitochondrial DNA, produced PCR products with different sizes which allow easy species identification without further sequencing. Based on published CHD 1 sequences, we designed internal primers (Gsex-F and Gsex-R) for sex determination that can be used in nested PCR after applying P2/P8 primers, and our methods clearly showed high success rate of molecular sexing from non-invasive samples. These molecular tools open the possibilities for genetic studies using non-invasive samples collected from a mixed-species aggregation containing bean geese and white-fronted geese.