assignR: Anrpackage for isotope-based geographic assignment

Methods for inferring geographic origin from the stable isotope composition of animal tissues are widely used in movement ecology, but few computational tools and standards for data interpretation are available. We introduce theassignRrpackage, which provides a structured, flexible toolkit for isotope-based migration data analysis and interpretation using a widely adopted semi-parametric Bayesian inversion method. assignRbundles data resources and functions that support data interpretation, hypothesis-testing and quality assessment, allowing end-to-end data analysis with only a few lines of code. Tools for post hoc analysis offer robust, standardized methods for aggregating information from multiple individuals, assignment of individuals to a sub-region of the study area and comparison of potential regions of origin using odds ratios. Assessment tools quantify the quality and power of the isotopic assignments and can be used to test prototype study designs. TheassignRpackage should increase the accessibility of isotopic geolocation methods.assignRsupports flexible data sources and analysis decisions, making it suitable for a wide range of applications, but also promotes standardization that will help foster increased consistency and comparability among studies and a more holistic understanding of animal migration. Lastly,assignRcan help make isotope-based geolocation research more efficient by helping researchers plan projects to be optimally aligned with their research questions.