Experimental recolonization of secondary forests by a Caribbean anole follows predictions from range expansion theory

Recovery dynamics are a defining feature of the Anthropocene landscape. These processes, shaped by ecological and evolutionary mechanisms, can be investigated through multiple theoretical frameworks. Among them, range expansion theory is increasingly recognized as a powerful lens for understanding recovery, particularly the recolonization of fauna. While previous studies have documented the spatial patterns of fauna recolonization, the underlying eco-evolutionary mechanisms remain less well understood. Range expansion theory predicts that the individuals recolonizing recovering forests are not random representatives of the source population. Instead, they are expected to exhibit lower initial densities, possess phenotypic traits favoring dispersal, and experience reduced parasitism. We experimentally tested these predictions using Anolis gundlachi, a shade-dwelling lizard recolonizing regenerating forests in Puerto Rico. We established small forest patches at varying distances from an old-growth reference site and compared lizard traits between the source and recolonizing populations. We assessed capture rates, dispersal-related morphology (e.g., limb and body size), and parasitic infection by Plasmodium spp. among individuals in the source population and those using the newly planted forest patches. Our results revealed that the individuals from the old-growth population that ventured to the young forests were a non-random subset of the source population with distinct traits related to movement capacity. While such results support predictions of trait-based dispersal during early recolonization, we observed no significant differences in parasitism across treatments. Our findings support range expansion theory as an appropriate framework to study early-stage recolonization and highlight the dynamic interplay of density, phenotypic filtering, and local conditions.