My PhD project focusses on the impacts of personality on spatial, genetic and population dynamics of small, terrestrial mammals: the deer mouse (Peromyscus maniculatus) and the southern red-backed vole (Myodes gapperi) among a series of island (Winnipeg river, Ontario, Canada). Island environments qualify as "natural laboratories", since they are closed and generally simpler than oceanic and continental systems, and have been studied extensively. Indeed several theories on these environments have emerged (island syndrome, dispersal syndrome, etc.). However only few studies on islands have taken into account behavioural inter-individual variability. Thus, my PhD includes the animal personality concept. Personality traits are defined by phenotypic behavioural tendencies (such as boldness, aggression, activity level or sociability of individuals) which are consistent across time and contexts. Several studies have demonstrated that these phenotypic behavioural traits are often connected to morphological, metabolic, hormonal and immune traits. The relationship between this set of traits can thus be studied through an individual’s pace-of-life syndrome ("POLS"). Many studies have demonstrated that personality traits and more broadly "POLS" could have an impact on individual fitness and characteristics of the population and environment. This PhD project is made up of three sub-objectives: (i) To study the relationship between individual personality and population spatial dynamics (i.e. dispersal), while accounting for contextual factors of sample sites (island area, island-mainland distance, inter-island distance, micro-habitat, etc.) ; (ii) To assess this spatial dynamic influence on inter-population gene flow and on the population genetic structures At the same time, I will evaluate the selection factors operating on individuals phenotypic traits (behavioural, physiological and morphological) ; (iii) To relate personality and dispersal patterns with the rodent community dynamics. This project will link many ecological dimensions but also to expand this conceptual framework to incorporate inter-individual behavior with other disciplines such as habitat fragmentation and biological invasions.