Circuit‐theory applications to connectivity science and conservation

Abstract

Conservation practitioners have long recognized ecological connectivity as a global priority for preserving biodiversity and ecosystem function. In the early years of conservation science, ecologists extended principles of island biogeography to assess connectivity based on source patch proximity and other metrics derived from binary maps of habitat. From 2006 to 2008, the late Brad McRae introduced circuit theory as an alternative approach to model gene flow and the dispersal or movement routes of organisms. He posited concepts and metrics from electrical circuit theory as a robust way to quantify movement across multiple possible paths in a landscape, not just a single least-cost path or corridor. Circuit theory offers many theoretical, conceptual, and practical linkages to conservation science. We reviewed 459 recent studies citing circuit theory or the open-source software Circuitscape. We focused on applications of circuit theory to the science and practice of connectivity conservation, including topics in landscape and population genetics, movement and dispersal paths of organisms, anthropogenic barriers to connectivity, fire behavior, water flow, and ecosystem services. Circuit theory is likely to have an effect on conservation science and practitioners through improved insights into landscape dynamics, animal movement, and habitat-use studies and through the development of new software tools for data analysis and visualization. The influence of circuit theory on conservation comes from the theoretical basis and elegance of the approach and the powerful collaborations and active user community that have emerged. Circuit theory provides a springboard for ecological understanding and will remain an important conservation tool for researchers and practitioners around the globe.Aplicaciones de la Teoría de Circuitos a la Conservación y a la Ciencia de la Conectividad Resumen: Quienes practican la conservación han reconocido durante mucho tiempo que la conectividad ecológica es una prioridad mundial para la preservación de la biodiversidad y el funcionamiento del * email: brett@csp-inc.org Article impact statement: Uses of circuit theory to understand connectivity have had a durable and global impact on conservation science and practice.

Genomic insights into adaptation to heterogeneous environments for the ancient relictual Circaeaster agrestis (Circaeasteraceae, Ranunculales)

“…Resistance distance was generated in Circuitscape v.4.0.5 based on circuit theory (McRae, 2006; McRae et al ., 2008). Circuit resistance provides models of connectivity or resistance to predict patterns of dispersal among sites in a heterogeneous landscape (McRae, 2006; Dickson et al ., 2019). The current ecological niche model (ENM) was calculated in M axent (Phillips & Dudik, 2008).…”

The oak syngameon: more than the sum of its parts

“…We argue here that the syngameon is more than the sum of the pairwise interactions between species but instead represents a dynamic network of species, acting over large periods of time and at continental scales. Like most networks, the syngameon should exhibit synergistic and emergent properties not seen in the constituent parts, as found in the application of circuit theory in ecology and conservation (McRae et al ., ; Dickson et al ., ). For instance, some species could act as a genetic conduit among otherwise disjunct species, with feedback loops of gene flow acting over millennial cycles.…”

A range‐wide model of contemporary, omnidirectional connectivity for the threatened Mojave desert tortoise

“…, Dickson et al. ). We first created two pairs of parallel nodes (one‐pixel wide) that extended across the approximately eastwest and northsouth edges of the tortoise range, respectively.…”

“…We used the map of landscape conductance to model omnidirectional connectivity, which predicts potential connectivity across a landscape without regard to the location of core habitat or population areas (Pelletier et al 2014). Specifically, we applied a circuit-theoretic model of connectivity, which relates the flow of current through an electrical circuit to the movement of individuals through a landscape and reflects the likelihoods of dispersal and gene flow (McRae and Beier 2007, McRae et al 2008, Dickson et al 2018. We first created two pairs of parallel nodes (one-pixel wide) that extended across the approximately eastwest and northsouth edges of the tortoise range, respectively.…”