Urban landscapes provide habitable patches for wildlife, but structural variability (e.g., land use, building materials) and aspects of human behavior and policy can alter their distribution, movement patterns, and resultant patterns of genetic variation. Recent studies show that landscape heterogeneity in cities can generate fine-scale genetic structure across even widely distributed species such as commensal brown rats (Rattus norvegicus), but the ecological mechanisms contributing to observed patterns of gene flow for this species remain undescribed. Using a population of urban brown rats inhabiting Manhattan in New York City, we assessed both structural connectivity (i.e., habitat distribution) and functional connectivity (i.e., realized gene flow) to quantify the effects of natural, social, and structural variation. We used a municipal rat inspection program to develop a habitat suitability model with Maxent and independently generated 61k genome-wide SNPs for 262 individual-based samples for use in landscape genetic analysis.
Results/Conclusions
Preliminary results suggest that habitat availability for urban brown rats is largely influenced by the building age, residential density, and median income of residents. In contrast, initial landscape genetic analysis suggested that the availability of earthen space, density of restaurants, and presence of community-based sanitation programs influence rat gene flow. Forthcoming results using linear mixed effects models and resistance layer optimization may reveal more nuanced conclusions. This work demonstrates the importance of studying both structural and functional connectivity for understanding the ecology of wildlife populations and provides new insights into the movement dynamics of human commensal species living in dense, heterogeneous urban landscapes. Additionally, our results should inform rat management strategies for cities and pest management professionals with the potential for improved public health and reduced economic costs associated with urban brown rats.