Parasites and ecosystem engineering: what roles could they play?

In recent years, there has been a growing interest in understanding the eco logical importance of ecosystem engineers. In this paper we argue that para sites, through the phenotypic alterations they induce in their hosts, are l ikely to be involved in engineering processes for at least two reasons. Fir st, when ecosystem engineers are themselves infected, phenotypic alteration s induced by parasites can interfere with host traits involved in the engin eering processes. Secondly, parasites themselves can be ecosystem engineers since the phenotypic alterations of hosts directly modify the habitat of a ll the species inhabiting free-living organisms. This new research area at the interface between ecology and parasitology should improve our understan ding of the ecological consequences of phenotypic alterations induced by pa rasites in ecosystems.