Abstract
This chapter explores how the presence of parasites can affect the evolution of host life- history traits (reproduction, longevity and dispersal), and conversely, how host demography or life history selects for changes in parasite life history (latency, within-host growth, transmission/dispersal). We discuss how shifts in host life history can mitigate the negative effects of parasites and look for evidence of parasite-mediated changes in life history in different systems. Parasite life history parallels that of free-living organisms, but with the added problem of virulence. How virulence relates to other parasite life history traits is quintessential for parasite fitness. This is because transmission requires exploitation of host resources, which reduces host health. At the same time, parasite life history (and by definition virulence) evolution are at the mercy of host demography. We present different results highlighting parasite life history (and virulence) evolution in response to different host mortality regimes, timing and/or mode of transmission. We further discuss how dispersal, as both a host and parasite life history trait, affects reciprocal evolution of both players and how it covaries with other traits (e.g., virulence). To illustrate the importance of the biotic environment, we provide an overview of how co-infection, when a host is infected with more than 1 parasite, can affect both host and parasite life history evolution. One main general message is that theoretical predictions depend on correlations between different life history traits and between life history and interaction traits (e.g., resistance, infectivity, etc.). Thus the genetic trait architecture in host and parasite might be a key determinant of epidemiological feedbacks and (co)evolutionary outcomes. This highlights the importance of studying host- parasite life history across scales, from the individual to the metapopulation to the community level.