Low-coverage whole genome sequencing for highly accurate population assignment: Mapping migratory connectivity in the American Redstart (Setophaga ruticilla)

Understanding the geographic linkages among populations across the annual
cycle is an essential component for understanding the ecology and
evolution of migratory species and for facilitating their effective
conservation. While genetic markers have been widely applied to describe
migratory connections, the rapid development of new sequencing methods,
such as low-coverage whole genome sequencing (lcWGS), provides new
opportunities for improved estimates of migratory connectivity. Here, we
use lcWGS to identify fine-scale population structure in a widespread
songbird, the American Redstart (Setophaga ruticilla), and accurately
assign individuals to genetically distinct breeding populations.
Assignment of individuals from the nonbreeding range reveals
population-specific patterns of varying migratory connectivity. By
combining migratory connectivity results with demographic analysis of
population abundance and trends, we consider full annual cycle
conservation strategies for preserving numbers of individuals and genetic
diversity. Notably, we highlight the importance of the Northern
Temperate-Greater Antilles migratory population as containing the largest
proportion of individuals in the species. Finally, we highlight valuable
considerations for other population assignment studies aimed at using
lcWGS. Our results have broad implications for improving our understanding
of the ecology and evolution of migratory species through conservation
genomics approaches.