The mechanistic basis of the immune response in Drosophila has been widely studied; however, little is known about the evolutionary and physiological mechanisms that drive local adaptation to pathogens. It is also unknown if this adaptation is dependent on factors such as the infected life-stage, route of infection or pathogen type(s) and the associated trade-offs. We have used Drosophila outbred populations, in collaboration with Sara Magalhães (University of Lisbon) and Luis Teixeira (IGC), to conduct experimental evolution to different and contrasting immune challenges. We have shown that adaptation to pathogens often relies on simple genetic basis, is highly pathogen specific, highly contingent on infection route and implies little trade-offs with other life-history traits. We are currently determining in detail the genetic changes that underlie these adaptive processes using deep-sequencing technology in collaboration with Christian Schlötterer (Vienna, Austria).

We have shown previously that, contrary to the current view, Drosophila plasmatocytes (the functional analogues of vertebrate macrophages) constitute a heterogeneous population. This has been established through a novel protocol for hemocyte purification using a combination of GFP lines, specific staining and FACS analysis. Currently, we are using this technology and this knowledge to assess the putative roles of the different sub-populations in immunity and development. Using different genetic tricks to manipulate the populations under different challenges and throughout hematopoiesis, we have revealed novel control mechanisms that regulate these subpopulations. We aspire at revealing novel levels of complexity in the development and physiology of the innate response of Drosophila with the ultimate aim of contributing to a better understanding of this system in vertebrates and its evolution across metazoan.