Genetic tagging in the Anthropocene: scaling ecology from alleles to ecosystems

The Anthropocene is an era of marked human impact on the world. Quantifying these impacts has become central to understanding the dynamics of coupled human‐natural systems, resource‐dependent livelihoods, and biodiversity conservation. Ecologists are facing growing pressure to quantify the size, distribution, and trajectory of wild populations in a cost‐effective and socially acceptable manner. Genetic tagging, combined with modern computational and genetic analyses, is an under‐utilized tool to meet this demand, especially for wide‐ranging, elusive, sensitive, and low‐density species. Genetic tagging studies are now revealing unprecedented insight into the mechanisms that control the density, trajectory, connectivity, and patterns of human–wildlife interaction for populations over vast spatial extents. Here, we outline the application of, and ecological inferences from, new analytical techniques applied to genetically tagged individuals, contrast this approach with conventional methods, and describe how genetic tagging can be better applied to address outstanding questions in ecology. We provide example analyses using a long‐term genetic tagging dataset of grizzly bears in the Canadian Rockies. The genetic tagging toolbox is a powerful and overlooked ensemble that ecologists and conservation biologists can leverage to generate evidence and meet the challenges of the Anthropocene. The extent to which climate change and habitat loss will impact the density and distribution of wild populations in the future is one of the greatest sources of scientific uncertainty in modern ecology and conservation (Dirzo et al. 2014, Lewis and Maslin 2015, Ibisch et al. 2016, Newbold et al. 2016, Krebs 2018). Resolving this uncertainty requires a mechanistic approach to understand the processes that limit the distribution and abundance of organisms: ecology's central question. Equipped with a robust set of quantitative tools, investigators are in a strong position to derive new insights from environmental change to reveal the mechanisms driving population change. Currently, four broad questions structure this line of inquiry: (1) Why and how does population density change across space? (2) Why and how does population size change through time? (3) How and at what rate do organisms move between populations and across space? (4) How can negative interactions between people and wildlife be mitigated? These questions form the basis of the heart of ecology and unanswered questions at its frontier (Sutherland et al. 2013). Further, questions 1–4 are not mutually exclusive, with