Beyond the Next Step: A Multi-Criteria Generative Validation Framework for Step Selection Functions

This repository contains the code required to reproduce the analyses, synthetic stress tests, and empirical case studies presented in the manuscript:

Nicosia, A. Beyond the Next Step: A Multi-Criteria Generative Validation Framework for Step Selection Functions. (Methods in Ecology and Evolution)

Repository Structure

This repository contains the canonical code associated with the paper, isolated into four categories:

• Functions/: Contains diagnose_issf.R. This script defines the four-pillar validation framework (Wasserstein, MSD, sinuosity, barrier crossing) applied to standard iSSA.
• Simulations/: Contains the R scripts used to run the synthetic stress-test scenarios (Scenarios 1 to 6) evaluating structural failure modes.
• Data_Analysis/: Contains red_deer_empirical_analysis_final.R, the empirical application of the framework to the red deer dataset.
• Supplementary/: Contains barrier_crossing_sensitivity.R and associated sensitivity analyses from Supplementary Information S3.
• docs/: Includes environment/documentation files like sessionInfo.txt.

(Note: Red deer data utilized in the empirical application are acquired programmatically via the amt R package. There is no redundant raw .csv or .rds data file included in this repository.)

Dependencies

The code requires R and standard movement ecology and spatial packages, notably:

• amt (for iSSA fitting and the built-in red deer dataset)
• transport (for Wasserstein distance calculation via the network simplex algorithm)
• terra, sf (for spatial operations)
• ggplot2, patchwork (for visualization)