Novel statistical methods for integrating genetic and stable isotope data to infer individual‐level migratory connectivity

Abstract

Methods for determining patterns of migratory connectivity in animal ecology have historically been limited due to logistical challenges. Recent progress in studying migratory bird connectivity has been made using genetic and stable-isotope markers to assign migratory individuals to their breeding grounds. Here, we present a novel Bayesian approach to jointly leverage genetic and isotopic markers and we test its utility on two migratory passerine bird species. Our approach represents a principled model-based combination of genetic and isotope data from samples collected on the breeding grounds and is able to achieve levels of assignment accuracy that exceed those of either method alone. When applied at large scale the method can reveal specific migratory connectivity patterns. In Wilson's warblers (Wilsonia pusilla), we detect a subgroup of birds wintering in Baja that uniquely migrate preferentially from the coastal Pacific Northwest. Our approach is implemented in a way that is easily extended to accommodate additional sources of information (e.g. bi-allelic markers, species distribution models, etc.) or adapted to other species or assignment problems.

Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation

“…Another avenue is the use of multiple isotopes, especially if they can be associated with a predictable isoscape surface such as those provided by plant physiology models (e.g., , García-Pérez and Hobson 2014. Finally, there is much promise in combining isotopic results with patterns of genetic variation (Boulet et al 2006, Chabot et al 2012, Rundel et al 2013, Ruegg et al 2014). …”

Within-Site Variation in Feather Stable Hydrogen Isotope (δ2Hf) Values of Boreal Songbirds: Implications for Assignment to Molt Origin

“…Results from Vander Zanden et al [52] also suggest that the need to use year-specific δ 2 H f isoscapes would depend on the study region because the degree of inter-annual variation in δ 2 H p differs among regions. It is also likely that we are close to identifying the limit of accuracy of this single isotope approach, highlighting the importance of combining multiple markers in multivariate assignment tests [59, 61–63]. …”

Full Issue

“…This d 2 H f -d 2 H p discontinuity in the lower Colorado River, if not appropriately accounted for, may cause inappropriate inferences of breeding dispersal and migration for this, and perhaps other, species. This discontinuity might be adequately accounted for by the incorporation of additional isotopes or genetic markers (Rundel et al 2013). For the Burrowing Owl, however, the use of genetic markers may not be an option, given that breeding populations across North America have low genetic differentiation in microsatellite and mitochondrial DNA markers (Korfanta et al 2005, Macias-Duarte 2011.…”