Ilkka Aulis Hanski. 14 February 1953—10 May 2016

Professor Ilkka Hanski made seminal contributions to both empirical and theoretical ecology and evolutionary biology, in particular metapopulation biology, throughout his scientific career. He started his career with dung beetle ecology, earning his doctorate at University of Oxford in 1979. He developed the rest of his career at University of Helsinki, where he was appointed professor in ecology in 1993 and academy professor in 2006. Hanski's most influential research was based on empirical work on the Glanville fritillary metapopulation in the Åland Islands, started in 1991, and continued until his death. His early research focused on ecological aspects of metapopulation biology, such as how the spatial structure of a landscape influences extinction thresholds, whereas his later work focused on genetic and evolutionary processes, such as maintenance of genetic variation by selection pressures varying with landscape structure. During the last years of his career, Hanski was a pioneer in the field of eco-evolutionary dynamics, showing how molecular-level underpinnings of trait variation can explain rapid evolutionary changes in natural populations. Hanski actively applied his research findings to conservation biology, involving himself in debates ranging from forest conservation in Finland to the links between human health and biodiversity. He was an exceptionally devoted group leader and mentor of younger researchers. His Metapopulation Research Centre grew gradually from a group consisting of Hanski and a few PhD students into a centre of 70 researchers.