Ecology and evolution unfold in spatially structured communities, where dispersal links dynamics across scales. Because dispersal is multicausal, identifying general drivers remains challenging. In a coordinated distributed experiment spanning organisms from protozoa to vertebrates, we tested whether two fundamental determinants of local dynamics, top-down and bottom-up control, generally explain active dispersal. We show that both factors consistently increased emigration rates and use metacommunity modelling to highlight consequences on local and regional dynamics.

Climate change, potentially increased by anthropogenic pressure, is still poorly considered in species status assessments for conservation. Terrestrial gastropods are expected to be greatly impacted, with subsequent effects on ecosystem functioning. We show the need to integrate physiological and behavioural traits to improve projection of the effects of climate change and conservation management for species at risk.

No abstract

Summary1. Intra-and interspecific differences in movement behaviour play an important role in the ecology and evolution of animals, particularly in fragmented landscapes. As a consequence of rarer and generally more fragmented habitat, and because dispersal tends to disrupt benefits brought by local adaptation, theory predicts that mobility and dispersal should be counterselected in specialists. 2. Using experimental data and phylogenetic comparative tools, we analysed movement propensity and capacity, as well as dispersal-related phenotypic traits, in controlled conditions in 20 species of European land snails from the Helicoidea superfamily. Costs of movement in terrestrial gastropods are among the highest in animals, which make them a potentially powerful model to test these predictions. 3. Habitat specialists were indeed less likely to cross a boundary between a familiar and an unfamiliar substrate than generalists. They also had smaller feet, after accounting for size. Furthermore, exploring specialists were slower than generalists and had more tortuous trajectories, leading them to stay closer to the familiar patch. Movement traits were generally evolutionary labile, but some were constrained by body size, a phylogenetically conserved trait. 4. High specialization and low-dispersal ability are two traits often considered to increase species vulnerability to fragmentation, climate changes and extinction. This study confirms they should not be considered separately, due to their integration in a dispersal syndrome. Therefore, specialist species face double penalty under habitat loss and other environmental changes, making them more vulnerable to extinction and contributing to the biotic homogenization of communities.