INDIVIDUAL HETEROGENEITY IN DISPERSAL AND METAPOPULATION DYNAMICS – INDHET

The ecological and evolutionary functioning of natural populations facing habitat fragmentation, shift of their climatic envelopes, or a combination of these, relies on (1) the availability of functionally connected networks of habitats, and (2) the sufficient dispersal ability of species to track these dramatic changes, which is mostly dependent upon the presence and maintenance of alternative dispersal strategies. As dispersal also drives the spatial and temporal redistribution of genotypes that is inseparable from the evolution of life-history traits, dispersal is a key process allowing adaptations to changing environmental conditions. In particular, in rapidly evolving landscapes, dispersal plays a key role in allowing organisms to cope with changing environmental conditions. In the increasingly concerning context of habitat loss, fragmentation and global climate change, understanding individual heterogeneity (INDHET) in dispersal is thus of utmost importance. The aim of INDHET is to improve our understanding of dispersal by investigating the inter-individual context- and condition-dependent variation in dispersal decisions and by including the downstream interactions with other traits (e.g. life-history). Inter-individual heterogeneity in dispersal processes is probably strongly linked with inter-individual heterogeneity in other aspects of individual life history (body size, personality, hormonal levels, presence/absence of dispersal apparatus, etc…). Such phenotypic variations may be generated by genetic factors, environmental factors, and by the influence of environmental factors on genetic expression (i.e. reaction norm). They can be maintained by numerous and non exclusive pathways occurring at different scales of space and time, including gene flow, genetic drift, natural selection (disruptive selection, balanced selection) and sexual selection (assortative mating). Phenotypic variations are commonly encountered in the form of phenotypic plasticity, ontogenetic changes, sexual dimorphism and polymorphism. All these types of intra-population variations potentially trigger differences among individuals with respect to the best dispersal strategy to maximize fitness. INDHET will focus on inter-individual heterogeneity in dispersal-associated phenotypes: from its genesis through its maintenance to its effects on individual decisions and metapopulation dynamics, and will specifically address the following questions: (1) How is individual heterogeneity related to dispersal capacity generated and maintained? (2) How do inter-individual context- and condition-dependent variations act on dispersal decisions and what are the interactions with other traits (e.g. life-history)? (3) How does inter-individual variation in dispersal affect metapopulation dynamics in the face of increased habitat fragmentation and climate change? INDHET will encompass a wide array of study systems, from low to high complexity models: Tetrahymena thermophila (unicellular Ciliate), Pieris brassicae (large white butterfly, Insect ectotherm), Podarcis muralis (wall lizard, Vertebrate ectotherm) and Capreolus capreolus (roe deer, Vertebrate endotherm). Besides, by applying meta-analytical procedures to existing data sets, INDHET will assess how general are the conclusions issued from these model systems. INDHET provides thus the challenging opportunity to explore the existence of behavioural and life-history syndromes linked to dispersal tactics across a wide range of model systems so as to understand how dispersal might allow species to cope with man-induced environmental changes. Thoroughly deciphering the mechanisms that underlie both the genesis and maintenance of within-species inter-individual heterogeneity is of prime interest for eco-evolutionary studies. INDHET, by bridging the gap between theory and reality, will provide the opportunity to move one major step forward in our understanding of the spatial functioning of populations.