The emergence of imperfect philopatry and fidelity in spatially and temporally heterogeneous environments

Abstract

Repeatability in habitat use - often termed site fidelity - is widespread and ubiquitous. Often, used habitat areas may be inherited by offspring in a phenomenon called natal philopatry, leading to intergenerational repeatability in habitat preferences. Both fidelity and philopatry may represent strategies that could optimize fitness in spatially and temporally heterogeneous environments; however, the suite of ecological factors that encourage or discourage fidelity and philopatry remain poorly understood in most taxa. While turtles (Order Testudines) exhibit both fidelity and natal philopatry when selecting nesting areas, emerging evidence suggests that nest choice may be more plastic than previously thought. However, few studies to date have attempted to explore the behavioral choices that may produce deviations from nest site fidelity and philopatry. We used a spatially-explicit, individual-based model to explore how behavioral responses to a heterogeneous landscape can generate population-level patterns of fidelity and philopatry. We demonstrate that this model can dispersal patterns inferred from behavioral and genetic data from a Blanding's Turtle (Emydoidea blandingii) population in central Wisconsin. Reduced philopatry was associated with increasing error rates in habitat discrimination, and reduced site fidelity was associated with decreasing risk tolerance. Unpredictable spatial distributions of risk increased natal philopatry but decreased site fidelity overall, suggesting that strong natal imprinting may sometimes be associated with rapid shifts in habitat preferences in unpredictable environments. Associating risk exposure with increased adult or nest mortality led to increased nest site fidelity in both cases, but with relatively weak effects on natal philopatry. We also demonstrate the utility of this model for other landscapes and species by exploring a simplified seabird system. Our model holds promise for more detailed exploration of the ecological and evolutionary factors that may give rise to fidelity and philopatry.