Beyond Roadkill, Radiotracking, Recapture and FST—a Review of Some Genetic Methods to Improve Understanding of the Influence of Roads on Wildlife

Abstract

Habitat fragmentation continues to occur despite increasing evidence of its adverse effects on ecosystems. One of the major detrimental effects of roads and traffic is the creation of barriers or filters to the movement of wildlife, ultimately disconnecting some populations. The authors' understanding of the extent to which roads reduce the movement of biota is mostly based on field-based observational methods of inferring animal movement, and to a much smaller extent, on allele frequency-based genetic analyses. Field-based methods, as it is typically feasible to apply them, tend to be informative at fine temporal and spatial scales. Allele frequency-based genetic methods are informative at broad geographic scales but at timescales usually greater than recent disturbance events. Contemporary analyses based on genotypes of individual organisms (called “genotypic” approaches herein) can augment these other approaches. They can be informative at fine spatial and temporal scales, are readily scaled up, and are complementary to the other field-based approaches. In genotypic analyses, every capture can be effectively a recapture, relieving a major limitation in sample size. They can evaluate the influence of even recently constructed roads on movements and their emergent effects on important population processes at the spatial and temporal scales of interest to wildlife and infrastructure managers. Information derived from genetic and field-based methods can be used to model the viability of populations influenced by roads and to evaluate and monitor mitigation efforts. Despite some excellent examples, the authors suggest that such applications are still rare relative to their potential. This paper emphasizes some of the detailed inferences that can be made using different types of genetic analyses, and suggests paths by which researchers in road ecology can incorporate genetic approaches. The authors recommend that the proven capacities of genetic techniques be routinely explored as approaches to quantify the diverse influences of roads on wildlife populations. With appropriate expertise, molecular ecology can be done extremely inexpensively. It is conducted within the same funding frameworks as field-based approaches and, in budgeting funding applications, molecular ecology maintenance costs are about 20–30% of payroll, in line with other disciplines and approaches. This and other common arguments against application of genetic approaches are often based on misconceptions, or limitations that no longer apply.