Understanding the feedback between spatial structuring and evolution is a major goal of research in evolutionary ecology. A large body of theory has been developed in population genetics to quantify the degree of genetic structure of populations, but this often hinges on the assumption that population size is constant. At the same time, ecologists have long been interested in understanding the impact of spatial demographic structure on population dynamics. In this talk, I discuss some recent results which shed light on how genetic and demographic structuring both interplay to generate selective pressures in space. Using the example of host-parasite interactions, I will present and compare two modelling frameworks for the evolution of host and parasite life-history traits in space. First, I discuss an adaptive dynamics model in which invasion fitness is shown to depend on measures of epidemiological structure and on measures of genetic relatedness that coincide with classical relatedness coefficients from inclusive fitness theory. In particular, this provides an alternative, ecological route to the celebrated result of inclusive fitness theory that parasite virulence should decrease with relatedness, but with some important additional twists. Second, I relax the assumption of low mutation rates and present a population-genetics model with explicit epidemiological dynamics. This leads to insightful equations for the dynamics of the mean transmission and virulence in the parasite population. I conclude by discussing the conceptual and practical advantages of the two approaches.