From individuals’ movement to range shifts: integration of movement data in individual-based models to assess global change effects on populations

Abstract

The study of the movement of individuals directly informs about home-range sizes, migratory routes or habitat selection. But also, integrating movement into ecological models allows for larger-scale studies. Here we summarize the results of our line of research based in the individual-based model STEPLAND. The model was parameterized with movement, demographic and genetic data of spur-thighed tortoises (Testudo graeca) in SE Spain. We developed different simulation experiments to answer questions about the effects of global change on the conservation of this species. At the species level, we identified those evolutionary traits of tortoises, such as female sperm storage, that prevent extinctions in human-altered habitats. At landscape scale, we assessed the impact of agricultural abandonment and agricultural intensification on the population dynamics of this long-lived species. Only agricultural intensification negatively affected reproductive rates, population density, and probability of extinction of T. graeca, with time-lag responses of 20, 30 and 130 years respectively. Finally, in a regional context, we aim to simulate the early stages of a range expansion. Preliminary results reveal patterns compatible to “genetic surfing”, a process affecting the expansion of low dispersal species impacted by strong genetic drift. We believe that our line of research exemplifies well that the scientific value of movement data goes well beyond the individual level.