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Dispersal is a process of central importance for the ecological and evolutionary dynamics of populations and communities, because of its diverse consequences for gene flow and demography. It is subject to evolutionary change, which begs the question, what is the genetic basis of this potentially complex trait? To address this question, we (i) review the empirical literature on the genetic basis of dispersal, (ii) explore how theoretical investigations of the evolution of dispersal have represented the genetics of dispersal, and (iii) discuss how the genetic basis of dispersal influences theoretical predictions of the evolution of dispersal and potential consequences. Dispersal has a detectable genetic basis in many organisms, from bacteria to plants and animals. Generally, there is evidence for significant genetic variation for dispersal or dispersal-related phenotypes or evidence for the micro-evolution of dispersal in natural populations. Dispersal is typically the outcome of several interacting traits, and this complexity is reflected in its genetic architecture: while some genes of moderate to large effect can influence certain aspects of dispersal, dispersal traits are typically polygenic. Correlations among dispersal traits as well as between dispersal traits and other traits under selection are common, and the genetic basis of dispersal can be highly environment-dependent. By contrast, models have historically considered a highly simplified genetic architecture of dispersal. It is only recently that models have started to consider multiple loci influencing dispersal, as well as non-additive effects such as dominance and epistasis, showing that the genetic basis of dispersal can influence evolutionary rates and outcomes, especially under non-equilibrium conditions. For example, the number of loci controlling dispersal can influence projected rates of dispersal evolution during range shifts and corresponding demographic impacts. Incorporating more realism in th

Dispersal, i.e. movements potentially leading to gene flow, is central in evolutionary ecology. Many factors can trigger dispersal, all linked to the social and/or the environmental context. Moreover, it is now widely demonstrated that phenotypes with contrasted dispersal abilities coexist within populations of a same species. The current challenge is to elucidate how social and environmental factors will influence the dispersal decision of individuals with distinct phenotypes. We have used the Metatron, a unique experimental mesocosm dedicated to the study of dispersal within fragmented landscapes, to analyze the relative and interactive roles played by ten potential dispersal triggers in experimental two-patch metapopulations of butterflies. We demonstrate in our model species that some factors (flight performance and wing length) have direct effects on emigration decision, others act only through interactive effects (sex ratio), while a third class of factors presents both direct and interactive effects (weather conditions, habitat quality and sex). We also show that disperser and resident individuals have distinct behavioral and morphological attributes, revealing the existence of a dispersal syndrome. Finally, our results also suggest that the environmental context, and especially weather conditions and habitat quality, prevails over social factors and individual phenotypes in butterflies' decision to disperse. Our approach is applicable to many species facing medium to strong environmental fluctuations, and constitutes a new way to master the idiosyncrasy of the dispersal process. Our framework should also help prioritize the factors responsible for populations' spatial distribution, which is obviously crucial in the current era of global changes.

Dispersal is fundamental in determining biodiversity responses to rapid climate change, but recently acquired ecological and evolutionary knowledge is seldom accounted for in either predictive methods or conservation planning. We emphasise the accumulating evidence for direct and indirect impacts of climate change on dispersal. Additionally, evolutionary theory predicts increases in dispersal at expanding range margins, and this has been observed in a number of species. This multitude of ecological and evolutionary processes is likely to lead to complex responses of dispersal to climate change. As a result, improvement of models of species’ range changes will require greater realism in the representation of dispersal. Placing dispersal at the heart of our thinking will facilitate development of conservation strategies that are resilient to climate change, including landscape management and assisted colonisation. Synthesis This article seeks synthesis across the fields of dispersal ecology and evolution, species distribution modelling and conservation biology. Increasing effort focuses on understanding how dispersal influences species' responses to climate change. Importantly, though perhaps not broadly widely-recognised, species' dispersal characteristics are themselves likely to alter during rapid climate change. We compile evidence for direct and indirect influences that climate change may have on dispersal, some ecological and others evolutionary. We emphasise the need for predictive modelling to account for this dispersal realism and highlight the need for conservation to make better use of our existing knowledge related to dispersal.