Sandra Lass

I am interested in the ecology and evolution of interspecific interactions — including host-parasite and predator-prey dynamics. I combine observational and experimental data to quantitatively test predictions of epidemiological and evolutionary theory, answering questions like:

• How does disease spread? What causes heterogeneities in host susceptibility and their ability to transmit diseases?
• How do parasites affect individual hosts and how are these effects manifested at the host population level?
• When and how do parasites control host population dynamics?
• How do interactions between different parasites or between a parasite and other members of a community affect disease dynamics?
• Why are parasites virulent? How does virulence evolve?

Parasite effects on individual hosts and on host populations

Parasites can have major effects on individual hosts, and hence on host populations; they can be a powerful selective force influencing host evolution. The parasite's ability to drive host evolution is determined by parasite transmission, persistence (prevalence) and detrimental effect on host fitness ( virulence). To date, much of the work in this area is theoretical; validation of theory with empirical data lags behind. I aim to fill this gap by testing predictions from epidemiological and evolutionary theory, using data gathered in laboratory and field settings.

Host-parasite interactions in a community context

A central question in evolutionary ecology is how interactions among organisms shape species' abundance and distribution, as well as their phenotypic and genotypic compositions. Many studies have investigated this question by focusing on interactions between just two species. However, species evolve in a community context, so focusing on pairwise interactions may be over-simplistic. For example, several parasite species can simultaneously infect a single host. I study how micro- and macroparasites that share a host may affect each other, their epidemiology and the ecology of their hosts.